Commenting on image diffs

77 files changed, 3318 insertions, 270 deletions

diff --git a/app/assets/images/icon_image_comment.svg b/app/assets/images/icon_image_comment.svg
new file mode 100644
index 00000000000..cf6cb972940
--- /dev/null
+++ b/app/assets/images/icon_image_comment.svg
@@ -0,0 +1 @@
+<svg width="24" height="30" viewBox="0 0 24 30" xmlns="http://www.w3.org/2000/svg"><title>cursor</title><g fill="none" fill-rule="evenodd"><path d="M24 12.105c0 6.686-5.74 11.58-12 17.895C5.74 23.684 0 18.79 0 12.105 0 5.42 5.373 0 12 0s12 5.42 12 12.105z" fill="#1F78D1" fill-rule="nonzero"/><path d="M15.28 25.249c1.458-1.475 2.539-2.635 3.474-3.747 2.851-3.394 4.203-6.265 4.203-9.397 0-6.111-4.908-11.062-10.957-11.062-6.05 0-10.957 4.951-10.957 11.062 0 3.132 1.352 6.003 4.203 9.397.935 1.112 2.016 2.272 3.474 3.747.511.517 2.216 2.213 3.28 3.275 1.064-1.062 2.769-2.758 3.28-3.275z" fill="#FFF"/><path d="M14.551 8.256A6.874 6.874 0 0 0 12 7.787c-.91 0-1.763.156-2.558.469-.79.308-1.42.725-1.888 1.252-.465.527-.697 1.096-.697 1.708 0 .5.159.977.476 1.433.321.45.772.841 1.352 1.172l.583.334-.181.643c-.107.407-.263.79-.469 1.152a6.604 6.604 0 0 0 1.842-1.145l.288-.254.381.04c.309.035.599.053.871.053.91 0 1.761-.154 2.551-.462.795-.312 1.424-.732 1.889-1.259.468-.526.703-1.096.703-1.707 0-.612-.235-1.181-.703-1.708-.465-.527-1.094-.944-1.889-1.252zm2.645.81c.536.656.804 1.373.804 2.15 0 .776-.268 1.495-.804 2.156-.535.656-1.263 1.176-2.183 1.56-.92.38-1.924.57-3.013.57a9.16 9.16 0 0 1-.971-.054 7.32 7.32 0 0 1-3.08 1.62 5.044 5.044 0 0 1-.764.148h-.033a.26.26 0 0 1-.181-.074.324.324 0 0 1-.107-.18v-.007c-.014-.018-.016-.045-.007-.08.014-.037.018-.059.014-.068 0-.009.01-.031.033-.067a.645.645 0 0 0 .04-.06 1.73 1.73 0 0 0 .047-.054l.054-.06a53.034 53.034 0 0 1 .435-.489c.049-.049.118-.136.207-.26.094-.126.168-.24.221-.342.054-.103.114-.235.181-.395.067-.161.125-.33.174-.51-.7-.397-1.254-.888-1.66-1.473A3.261 3.261 0 0 1 6 11.216c0-.777.268-1.494.804-2.15.535-.66 1.263-1.18 2.183-1.56.92-.384 1.924-.576 3.013-.576 1.09 0 2.094.192 3.013.576.92.38 1.648.9 2.183 1.56z" fill="#1F78D1" fill-rule="nonzero"/></g></svg>
diff --git a/app/assets/images/icon_image_comment@2x.svg b/app/assets/images/icon_image_comment@2x.svg
new file mode 100644
index 00000000000..83be91d3705
--- /dev/null
+++ b/app/assets/images/icon_image_comment@2x.svg
@@ -0,0 +1 @@
+<svg width="48" height="60" viewBox="0 0 48 60" xmlns="http://www.w3.org/2000/svg"><title>cursor_2x</title><g fill="none" fill-rule="evenodd"><path d="M48 24.21C48 37.583 36.522 47.369 24 60 11.478 47.368 0 37.582 0 24.21 0 10.84 10.745 0 24 0s24 10.84 24 24.21z" fill="#1F78D1" fill-rule="nonzero"/><path d="M30.56 50.497c2.915-2.95 5.078-5.268 6.947-7.493 5.703-6.788 8.406-12.53 8.406-18.793 0-12.223-9.815-22.124-21.913-22.124S2.087 11.988 2.087 24.211c0 6.263 2.703 12.005 8.406 18.793 1.87 2.225 4.032 4.544 6.947 7.493 1.022 1.035 4.432 4.426 6.56 6.55 2.128-2.124 5.538-5.515 6.56-6.55z" fill="#FFF"/><path d="M29.103 16.512c-1.58-.625-3.282-.938-5.103-.938-1.821 0-3.527.313-5.116.938-1.58.616-2.84 1.45-3.777 2.504-.928 1.054-1.393 2.192-1.393 3.415 0 1 .317 1.956.951 2.866.643.902 1.545 1.684 2.706 2.344l1.165.67-.362 1.286a9.603 9.603 0 0 1-.937 2.303 13.208 13.208 0 0 0 3.683-2.29l.576-.509.763.08c.616.072 1.196.108 1.741.108 1.821 0 3.522-.308 5.103-.925 1.589-.625 2.848-1.464 3.776-2.517.938-1.054 1.407-2.192 1.407-3.416 0-1.223-.469-2.361-1.407-3.415-.928-1.053-2.187-1.888-3.776-2.504zm5.29 1.62c1.071 1.313 1.607 2.746 1.607 4.3 0 1.553-.536 2.99-1.607 4.312-1.072 1.312-2.527 2.353-4.366 3.12-1.84.76-3.848 1.139-6.027 1.139a18.32 18.32 0 0 1-1.942-.107c-1.768 1.562-3.821 2.643-6.16 3.24-.438.126-.947.224-1.527.295h-.067a.521.521 0 0 1-.362-.147.649.649 0 0 1-.214-.362v-.013c-.027-.036-.032-.09-.014-.16.027-.072.036-.117.027-.135 0-.017.022-.062.067-.133a1.29 1.29 0 0 0 .08-.121c.01-.009.04-.045.094-.107a106.068 106.068 0 0 1 .522-.59c.215-.232.367-.401.456-.508.098-.099.236-.273.415-.523.188-.25.335-.477.442-.683.107-.205.228-.468.362-.79.134-.321.25-.66.348-1.018-1.402-.794-2.51-1.777-3.322-2.946C12.402 25.025 12 23.77 12 22.43c0-1.553.536-2.986 1.607-4.299 1.072-1.321 2.527-2.361 4.366-3.12 1.84-.768 3.848-1.152 6.027-1.152 2.179 0 4.188.384 6.027 1.152 1.84.759 3.294 1.799 4.366 3.12z" fill="#1F78D1" fill-rule="nonzero"/></g></svg>
diff --git a/app/assets/javascripts/commit.js b/app/assets/javascripts/commit.js
deleted file mode 100644
index 5f637524e30..00000000000
--- a/app/assets/javascripts/commit.js
+++ /dev/null
@@ -1,12 +0,0 @@
-/* eslint-disable func-names, space-before-function-paren, wrap-iife */
-/* global CommitFile */
-
-window.Commit = (function() {
-  function Commit() {
-    $('.files .diff-file').each(function() {
-      return new CommitFile(this);
-    });
-  }
-
-  return Commit;
-})();
diff --git a/app/assets/javascripts/commit/file.js b/app/assets/javascripts/commit/file.js
deleted file mode 100644
index ee087c978dd..00000000000
--- a/app/assets/javascripts/commit/file.js
+++ /dev/null
@@ -1,14 +0,0 @@
-/* eslint-disable func-names, space-before-function-paren, wrap-iife, no-new */
-/* global ImageFile */
-
-(function() {
-  this.CommitFile = (function() {
-    function CommitFile(file) {
-      if ($('.image', file).length) {
-        new gl.ImageFile(file);
-      }
-    }
-
-    return CommitFile;
-  })();
-}).call(window);
diff --git a/app/assets/javascripts/commit/image_file.js b/app/assets/javascripts/commit/image_file.js
index 4763985c802..e7adf8814b8 100644
--- a/app/assets/javascripts/commit/image_file.js
+++ b/app/assets/javascripts/commit/image_file.js
@@ -1,4 +1,6 @@
 /* eslint-disable func-names, space-before-function-paren, wrap-iife, no-var, no-use-before-define, prefer-arrow-callback, no-else-return, consistent-return, prefer-template, quotes, one-var, one-var-declaration-per-line, no-unused-vars, no-return-assign, comma-dangle, quote-props, no-unused-expressions, no-sequences, object-shorthand, max-len */
+import 'vendor/jquery.waitforimages';
+
 (function() {
   gl.ImageFile = (function() {
     var prepareFrames;
@@ -17,15 +19,10 @@
 
             // Load two-up view after images are loaded
             // so that we can display the correct width and height information
-            const images = $('.two-up.view img', _this.file);
-            let loadedCount = 0;
-
-            images.on('load', () => {
-              loadedCount += 1;
+            const $images = $('.two-up.view img', _this.file);
 
-              if (loadedCount === images.length) {
-                _this.initView('two-up');
-              }
+            $images.waitForImages(function() {
+              _this.initView('two-up');
             });
           });
         };
diff --git a/app/assets/javascripts/diff.js b/app/assets/javascripts/diff.js
index 9ddfdb6ae21..6c78662baa7 100644
--- a/app/assets/javascripts/diff.js
+++ b/app/assets/javascripts/diff.js
@@ -3,6 +3,7 @@
 import './lib/utils/url_utility';
 import FilesCommentButton from './files_comment_button';
 import SingleFileDiff from './single_file_diff';
+import imageDiffHelper from './image_diff/helpers/index';
 
 const UNFOLD_COUNT = 20;
 let isBound = false;
@@ -20,7 +21,9 @@ class Diff {
     const tab = document.getElementById('diffs');
     if (!tab || (tab && tab.dataset && tab.dataset.isLocked !== '')) FilesCommentButton.init($diffFile);
 
-    $diffFile.each((index, file) => new gl.ImageFile(file));
+    const firstFile = $('.files').first().get(0);
+    const canCreateNote = firstFile && firstFile.hasAttribute('data-can-create-note');
+    $diffFile.each((index, file) => imageDiffHelper.initImageDiff(file, canCreateNote));
 
     if (!isBound) {
       $(document)
diff --git a/app/assets/javascripts/diff_notes/components/jump_to_discussion.js b/app/assets/javascripts/diff_notes/components/jump_to_discussion.js
index 497c23f014f..e77910a83d4 100644
--- a/app/assets/javascripts/diff_notes/components/jump_to_discussion.js
+++ b/app/assets/javascripts/diff_notes/components/jump_to_discussion.js
@@ -171,7 +171,14 @@ const JumpToDiscussion = Vue.extend({
         // When jumping between unresolved discussions on the diffs tab, we show them.
         $target.closest(".content").show();
 
-        $target = $target.closest("tr.notes_holder");
+        const $notesHolder = $target.closest("tr.notes_holder");
+
+        // Image diff discussions does not use notes_holder
+        // so we should keep original $target value in those cases
+        if ($notesHolder.length > 0) {
+          $target = $notesHolder;
+        }
+
         $target.show();
 
         // If we are on the diffs tab, we don't scroll to the discussion itself, but to
diff --git a/app/assets/javascripts/dispatcher.js b/app/assets/javascripts/dispatcher.js
index e4e7cae540e..33271c25146 100644
--- a/app/assets/javascripts/dispatcher.js
+++ b/app/assets/javascripts/dispatcher.js
@@ -7,7 +7,6 @@
 /* global IssuableForm */
 /* global LabelsSelect */
 /* global MilestoneSelect */
-/* global Commit */
 /* global CommitsList */
 /* global NewBranchForm */
 /* global NotificationsForm */
@@ -316,7 +315,6 @@ import { ajaxGet, convertPermissionToBoolean } from './lib/utils/common_utils';
           new gl.Activities();
           break;
         case 'projects:commit:show':
-          new Commit();
           new gl.Diff();
           new ZenMode();
           shortcut_handler = new ShortcutsNavigation();
diff --git a/app/assets/javascripts/image_diff/helpers/badge_helper.js b/app/assets/javascripts/image_diff/helpers/badge_helper.js
new file mode 100644
index 00000000000..6a6a668308d
--- /dev/null
+++ b/app/assets/javascripts/image_diff/helpers/badge_helper.js
@@ -0,0 +1,38 @@
+export function createImageBadge(noteId, { x, y }, classNames = []) {
+  const buttonEl = document.createElement('button');
+  const classList = classNames.concat(['js-image-badge']);
+  classList.forEach(className => buttonEl.classList.add(className));
+  buttonEl.setAttribute('type', 'button');
+  buttonEl.setAttribute('disabled', true);
+  buttonEl.dataset.noteId = noteId;
+  buttonEl.style.left = `${x}px`;
+  buttonEl.style.top = `${y}px`;
+
+  return buttonEl;
+}
+
+export function addImageBadge(containerEl, { coordinate, badgeText, noteId }) {
+  const buttonEl = createImageBadge(noteId, coordinate, ['badge']);
+  buttonEl.innerText = badgeText;
+
+  containerEl.appendChild(buttonEl);
+}
+
+export function addImageCommentBadge(containerEl, { coordinate, noteId }) {
+  const buttonEl = createImageBadge(noteId, coordinate, ['image-comment-badge', 'inverted']);
+  const iconEl = document.createElement('i');
+  iconEl.className = 'fa fa-comment-o';
+  iconEl.setAttribute('aria-label', 'comment');
+
+  buttonEl.appendChild(iconEl);
+  containerEl.appendChild(buttonEl);
+}
+
+export function addAvatarBadge(el, event) {
+  const { noteId, badgeNumber } = event.detail;
+
+  // Add badge to new comment
+  const avatarBadgeEl = el.querySelector(`#${noteId} .badge`);
+  avatarBadgeEl.innerText = badgeNumber;
+  avatarBadgeEl.classList.remove('hidden');
+}
diff --git a/app/assets/javascripts/image_diff/helpers/comment_indicator_helper.js b/app/assets/javascripts/image_diff/helpers/comment_indicator_helper.js
new file mode 100644
index 00000000000..05000c73052
--- /dev/null
+++ b/app/assets/javascripts/image_diff/helpers/comment_indicator_helper.js
@@ -0,0 +1,58 @@
+export function addCommentIndicator(containerEl, { x, y }) {
+  const buttonEl = document.createElement('button');
+  buttonEl.classList.add('btn-transparent');
+  buttonEl.classList.add('comment-indicator');
+  buttonEl.setAttribute('type', 'button');
+  buttonEl.style.left = `${x}px`;
+  buttonEl.style.top = `${y}px`;
+
+  buttonEl.innerHTML = gl.utils.spriteIcon('image-comment-dark');
+
+  containerEl.appendChild(buttonEl);
+}
+
+export function removeCommentIndicator(imageFrameEl) {
+  const commentIndicatorEl = imageFrameEl.querySelector('.comment-indicator');
+  const imageEl = imageFrameEl.querySelector('img');
+  const willRemove = !!commentIndicatorEl;
+  let meta = {};
+
+  if (willRemove) {
+    meta = {
+      x: parseInt(commentIndicatorEl.style.left, 10),
+      y: parseInt(commentIndicatorEl.style.top, 10),
+      image: {
+        width: imageEl.width,
+        height: imageEl.height,
+      },
+    };
+
+    commentIndicatorEl.remove();
+  }
+
+  return Object.assign({}, meta, {
+    removed: willRemove,
+  });
+}
+
+export function showCommentIndicator(imageFrameEl, coordinate) {
+  const { x, y } = coordinate;
+  const commentIndicatorEl = imageFrameEl.querySelector('.comment-indicator');
+
+  if (commentIndicatorEl) {
+    commentIndicatorEl.style.left = `${x}px`;
+    commentIndicatorEl.style.top = `${y}px`;
+  } else {
+    addCommentIndicator(imageFrameEl, coordinate);
+  }
+}
+
+export function commentIndicatorOnClick(event) {
+  // Prevent from triggering onAddImageDiffNote in notes.js
+  event.stopPropagation();
+
+  const buttonEl = event.currentTarget;
+  const diffViewerEl = buttonEl.closest('.diff-viewer');
+  const textareaEl = diffViewerEl.querySelector('.note-container .note-textarea');
+  textareaEl.focus();
+}
diff --git a/app/assets/javascripts/image_diff/helpers/dom_helper.js b/app/assets/javascripts/image_diff/helpers/dom_helper.js
new file mode 100644
index 00000000000..12d56714b34
--- /dev/null
+++ b/app/assets/javascripts/image_diff/helpers/dom_helper.js
@@ -0,0 +1,44 @@
+export function setPositionDataAttribute(el, options) {
+  // Update position data attribute so that the
+  // new comment form can use this data for ajax request
+  const { x, y, width, height } = options;
+  const position = el.dataset.position;
+  const positionObject = Object.assign({}, JSON.parse(position), {
+    x,
+    y,
+    width,
+    height,
+  });
+
+  el.setAttribute('data-position', JSON.stringify(positionObject));
+}
+
+export function updateDiscussionAvatarBadgeNumber(discussionEl, newBadgeNumber) {
+  const avatarBadgeEl = discussionEl.querySelector('.image-diff-avatar-link .badge');
+  avatarBadgeEl.innerText = newBadgeNumber;
+}
+
+export function updateDiscussionBadgeNumber(discussionEl, newBadgeNumber) {
+  const discussionBadgeEl = discussionEl.querySelector('.badge');
+  discussionBadgeEl.innerText = newBadgeNumber;
+}
+
+export function toggleCollapsed(event) {
+  const toggleButtonEl = event.currentTarget;
+  const discussionNotesEl = toggleButtonEl.closest('.discussion-notes');
+  const formEl = discussionNotesEl.querySelector('.discussion-form');
+  const isCollapsed = discussionNotesEl.classList.contains('collapsed');
+
+  if (isCollapsed) {
+    discussionNotesEl.classList.remove('collapsed');
+  } else {
+    discussionNotesEl.classList.add('collapsed');
+  }
+
+  // Override the inline display style set in notes.js
+  if (formEl && !isCollapsed) {
+    formEl.style.display = 'none';
+  } else if (formEl && isCollapsed) {
+    formEl.style.display = 'block';
+  }
+}
diff --git a/app/assets/javascripts/image_diff/helpers/index.js b/app/assets/javascripts/image_diff/helpers/index.js
new file mode 100644
index 00000000000..4a100631003
--- /dev/null
+++ b/app/assets/javascripts/image_diff/helpers/index.js
@@ -0,0 +1,25 @@
+import * as badgeHelper from './badge_helper';
+import * as commentIndicatorHelper from './comment_indicator_helper';
+import * as domHelper from './dom_helper';
+import * as utilsHelper from './utils_helper';
+
+export default {
+  addCommentIndicator: commentIndicatorHelper.addCommentIndicator,
+  removeCommentIndicator: commentIndicatorHelper.removeCommentIndicator,
+  showCommentIndicator: commentIndicatorHelper.showCommentIndicator,
+  commentIndicatorOnClick: commentIndicatorHelper.commentIndicatorOnClick,
+
+  addImageBadge: badgeHelper.addImageBadge,
+  addImageCommentBadge: badgeHelper.addImageCommentBadge,
+  addAvatarBadge: badgeHelper.addAvatarBadge,
+
+  setPositionDataAttribute: domHelper.setPositionDataAttribute,
+  updateDiscussionAvatarBadgeNumber: domHelper.updateDiscussionAvatarBadgeNumber,
+  updateDiscussionBadgeNumber: domHelper.updateDiscussionBadgeNumber,
+  toggleCollapsed: domHelper.toggleCollapsed,
+
+  resizeCoordinatesToImageElement: utilsHelper.resizeCoordinatesToImageElement,
+  generateBadgeFromDiscussionDOM: utilsHelper.generateBadgeFromDiscussionDOM,
+  getTargetSelection: utilsHelper.getTargetSelection,
+  initImageDiff: utilsHelper.initImageDiff,
+};
diff --git a/app/assets/javascripts/image_diff/helpers/utils_helper.js b/app/assets/javascripts/image_diff/helpers/utils_helper.js
new file mode 100644
index 00000000000..96fc735e629
--- /dev/null
+++ b/app/assets/javascripts/image_diff/helpers/utils_helper.js
@@ -0,0 +1,95 @@
+import ImageBadge from '../image_badge';
+import ImageDiff from '../image_diff';
+import ReplacedImageDiff from '../replaced_image_diff';
+import '../../commit/image_file';
+
+export function resizeCoordinatesToImageElement(imageEl, meta) {
+  const { x, y, width, height } = meta;
+
+  const imageWidth = imageEl.width;
+  const imageHeight = imageEl.height;
+
+  const widthRatio = imageWidth / width;
+  const heightRatio = imageHeight / height;
+
+  return {
+    x: Math.round(x * widthRatio),
+    y: Math.round(y * heightRatio),
+    width: imageWidth,
+    height: imageHeight,
+  };
+}
+
+export function generateBadgeFromDiscussionDOM(imageFrameEl, discussionEl) {
+  const position = JSON.parse(discussionEl.dataset.position);
+  const firstNoteEl = discussionEl.querySelector('.note');
+  const badge = new ImageBadge({
+    actual: position,
+    imageEl: imageFrameEl.querySelector('img'),
+    noteId: firstNoteEl.id,
+    discussionId: discussionEl.dataset.discussionId,
+  });
+
+  return badge;
+}
+
+export function getTargetSelection(event) {
+  const containerEl = event.currentTarget;
+  const imageEl = containerEl.querySelector('img');
+
+  const x = event.offsetX;
+  const y = event.offsetY;
+
+  const width = imageEl.width;
+  const height = imageEl.height;
+
+  const actualWidth = imageEl.naturalWidth;
+  const actualHeight = imageEl.naturalHeight;
+
+  const widthRatio = actualWidth / width;
+  const heightRatio = actualHeight / height;
+
+  // Browser will include the frame as a clickable target,
+  // which would result in potential 1px out of bounds value
+  // This bound the coordinates to inside the frame
+  const normalizedX = Math.max(0, x) && Math.min(x, width);
+  const normalizedY = Math.max(0, y) && Math.min(y, height);
+
+  return {
+    browser: {
+      x: normalizedX,
+      y: normalizedY,
+      width,
+      height,
+    },
+    actual: {
+      // Round x, y so that we don't need to deal with decimals
+      x: Math.round(normalizedX * widthRatio),
+      y: Math.round(normalizedY * heightRatio),
+      width: actualWidth,
+      height: actualHeight,
+    },
+  };
+}
+
+export function initImageDiff(fileEl, canCreateNote, renderCommentBadge) {
+  const options = {
+    canCreateNote,
+    renderCommentBadge,
+  };
+  let diff;
+
+  // ImageFile needs to be invoked before initImageDiff so that badges
+  // can mount to the correct location
+  new gl.ImageFile(fileEl); // eslint-disable-line no-new
+
+  if (fileEl.querySelector('.diff-file .js-single-image')) {
+    diff = new ImageDiff(fileEl, options);
+    diff.init();
+  } else if (fileEl.querySelector('.diff-file .js-replaced-image')) {
+    diff = new ReplacedImageDiff(fileEl, options);
+    diff.init();
+  }
+
+  return diff;
+}
diff --git a/app/assets/javascripts/image_diff/image_badge.js b/app/assets/javascripts/image_diff/image_badge.js
new file mode 100644
index 00000000000..51a8cda98d7
--- /dev/null
+++ b/app/assets/javascripts/image_diff/image_badge.js
@@ -0,0 +1,23 @@
+import imageDiffHelper from './helpers/index';
+
+const defaultMeta = {
+  x: 0,
+  y: 0,
+  width: 0,
+  height: 0,
+};
+
+export default class ImageBadge {
+  constructor(options) {
+    const { noteId, discussionId } = options;
+
+    this.actual = options.actual || defaultMeta;
+    this.browser = options.browser || defaultMeta;
+    this.noteId = noteId;
+    this.discussionId = discussionId;
+
+    if (options.imageEl && !options.browser) {
+      this.browser = imageDiffHelper.resizeCoordinatesToImageElement(options.imageEl, this.actual);
+    }
+  }
+}
diff --git a/app/assets/javascripts/image_diff/image_diff.js b/app/assets/javascripts/image_diff/image_diff.js
new file mode 100644
index 00000000000..f3af92cf2b0
--- /dev/null
+++ b/app/assets/javascripts/image_diff/image_diff.js
@@ -0,0 +1,143 @@
+import imageDiffHelper from './helpers/index';
+import ImageBadge from './image_badge';
+import { isImageLoaded } from '../lib/utils/image_utility';
+
+export default class ImageDiff {
+  constructor(el, options) {
+    this.el = el;
+    this.canCreateNote = !!(options && options.canCreateNote);
+    this.renderCommentBadge = !!(options && options.renderCommentBadge);
+    this.$noteContainer = $('.note-container', this.el);
+    this.imageBadges = [];
+  }
+
+  init() {
+    this.imageFrameEl = this.el.querySelector('.diff-file .js-image-frame');
+    this.imageEl = this.imageFrameEl.querySelector('img');
+
+    this.bindEvents();
+  }
+
+  bindEvents() {
+    this.imageClickedWrapper = this.imageClicked.bind(this);
+    this.imageBlurredWrapper = imageDiffHelper.removeCommentIndicator.bind(null, this.imageFrameEl);
+    this.addBadgeWrapper = this.addBadge.bind(this);
+    this.removeBadgeWrapper = this.removeBadge.bind(this);
+    this.renderBadgesWrapper = this.renderBadges.bind(this);
+
+    // Render badges
+    if (isImageLoaded(this.imageEl)) {
+      this.renderBadges();
+    } else {
+      this.imageEl.addEventListener('load', this.renderBadgesWrapper);
+    }
+
+    // jquery makes the event delegation here much simpler
+    this.$noteContainer.on('click', '.js-diff-notes-toggle', imageDiffHelper.toggleCollapsed);
+    $(this.el).on('click', '.comment-indicator', imageDiffHelper.commentIndicatorOnClick);
+
+    if (this.canCreateNote) {
+      this.el.addEventListener('click.imageDiff', this.imageClickedWrapper);
+      this.el.addEventListener('blur.imageDiff', this.imageBlurredWrapper);
+      this.el.addEventListener('addBadge.imageDiff', this.addBadgeWrapper);
+      this.el.addEventListener('removeBadge.imageDiff', this.removeBadgeWrapper);
+    }
+  }
+
+  imageClicked(event) {
+    const customEvent = event.detail;
+    const selection = imageDiffHelper.getTargetSelection(customEvent);
+    const el = customEvent.currentTarget;
+
+    imageDiffHelper.setPositionDataAttribute(el, selection.actual);
+    imageDiffHelper.showCommentIndicator(this.imageFrameEl, selection.browser);
+  }
+
+  renderBadges() {
+    const discussionsEls = this.el.querySelectorAll('.note-container .discussion-notes .notes');
+    [...discussionsEls].forEach(this.renderBadge.bind(this));
+  }
+
+  renderBadge(discussionEl, index) {
+    const imageBadge = imageDiffHelper
+      .generateBadgeFromDiscussionDOM(this.imageFrameEl, discussionEl);
+
+    this.imageBadges.push(imageBadge);
+
+    const options = {
+      coordinate: imageBadge.browser,
+      noteId: imageBadge.noteId,
+    };
+
+    if (this.renderCommentBadge) {
+      imageDiffHelper.addImageCommentBadge(this.imageFrameEl, options);
+    } else {
+      const numberBadgeOptions = Object.assign({}, options, {
+        badgeText: index + 1,
+      });
+
+      imageDiffHelper.addImageBadge(this.imageFrameEl, numberBadgeOptions);
+    }
+  }
+
+  addBadge(event) {
+    const { x, y, width, height, noteId, discussionId } = event.detail;
+    const badgeText = this.imageBadges.length + 1;
+    const imageBadge = new ImageBadge({
+      actual: {
+        x,
+        y,
+        width,
+        height,
+      },
+      imageEl: this.imageFrameEl.querySelector('img'),
+      noteId,
+      discussionId,
+    });
+
+    this.imageBadges.push(imageBadge);
+
+    imageDiffHelper.addImageBadge(this.imageFrameEl, {
+      coordinate: imageBadge.browser,
+      badgeText,
+      noteId,
+    });
+
+    imageDiffHelper.addAvatarBadge(this.el, {
+      detail: {
+        noteId,
+        badgeNumber: badgeText,
+      },
+    });
+
+    const discussionEl = this.el.querySelector(`#discussion_${discussionId}`);
+    imageDiffHelper.updateDiscussionBadgeNumber(discussionEl, badgeText);
+  }
+
+  removeBadge(event) {
+    const { badgeNumber } = event.detail;
+    const indexToRemove = badgeNumber - 1;
+    const imageBadgeEls = this.imageFrameEl.querySelectorAll('.badge');
+
+    if (this.imageBadges.length !== badgeNumber) {
+      // Cascade badges count numbers for (avatar badges + image badges)
+      this.imageBadges.forEach((badge, index) => {
+        if (index > indexToRemove) {
+          const { discussionId } = badge;
+          const updatedBadgeNumber = index;
+          const discussionEl = this.el.querySelector(`#discussion_${discussionId}`);
+
+          imageBadgeEls[index].innerText = updatedBadgeNumber;
+
+          imageDiffHelper.updateDiscussionBadgeNumber(discussionEl, updatedBadgeNumber);
+          imageDiffHelper.updateDiscussionAvatarBadgeNumber(discussionEl, updatedBadgeNumber);
+        }
+      });
+    }
+
+    this.imageBadges.splice(indexToRemove, 1);
+
+    const imageBadgeEl = imageBadgeEls[indexToRemove];
+    imageBadgeEl.remove();
+  }
+}
diff --git a/app/assets/javascripts/image_diff/init_discussion_tab.js b/app/assets/javascripts/image_diff/init_discussion_tab.js
new file mode 100644
index 00000000000..2f16c6ef115
--- /dev/null
+++ b/app/assets/javascripts/image_diff/init_discussion_tab.js
@@ -0,0 +1,12 @@
+import imageDiffHelper from './helpers/index';
+
+export default () => {
+  // Always pass can-create-note as false because a user
+  // cannot place new badge markers on discussion tab
+  const canCreateNote = false;
+  const renderCommentBadge = true;
+
+  const diffFileEls = document.querySelectorAll('.timeline-content .diff-file.js-image-file');
+  [...diffFileEls].forEach(diffFileEl =>
+    imageDiffHelper.initImageDiff(diffFileEl, canCreateNote, renderCommentBadge));
+};
diff --git a/app/assets/javascripts/image_diff/replaced_image_diff.js b/app/assets/javascripts/image_diff/replaced_image_diff.js
new file mode 100644
index 00000000000..4abd13fb472
--- /dev/null
+++ b/app/assets/javascripts/image_diff/replaced_image_diff.js
@@ -0,0 +1,92 @@
+import imageDiffHelper from './helpers/index';
+import { viewTypes, isValidViewType } from './view_types';
+import ImageDiff from './image_diff';
+
+export default class ReplacedImageDiff extends ImageDiff {
+  init(defaultViewType = viewTypes.TWO_UP) {
+    this.imageFrameEls = {
+      [viewTypes.TWO_UP]: this.el.querySelector('.two-up .js-image-frame'),
+      [viewTypes.SWIPE]: this.el.querySelector('.swipe .js-image-frame'),
+      [viewTypes.ONION_SKIN]: this.el.querySelector('.onion-skin .js-image-frame'),
+    };
+
+    const viewModesEl = this.el.querySelector('.view-modes-menu');
+    this.viewModesEls = {
+      [viewTypes.TWO_UP]: viewModesEl.querySelector('.two-up'),
+      [viewTypes.SWIPE]: viewModesEl.querySelector('.swipe'),
+      [viewTypes.ONION_SKIN]: viewModesEl.querySelector('.onion-skin'),
+    };
+
+    this.currentView = defaultViewType;
+    this.generateImageEls();
+    this.bindEvents();
+  }
+
+  generateImageEls() {
+    this.imageEls = {};
+
+    const viewTypeNames = Object.getOwnPropertyNames(viewTypes);
+    viewTypeNames.forEach((viewType) => {
+      this.imageEls[viewType] = this.imageFrameEls[viewType].querySelector('img');
+    });
+  }
+
+  bindEvents() {
+    super.bindEvents();
+
+    this.changeToViewTwoUp = this.changeView.bind(this, viewTypes.TWO_UP);
+    this.changeToViewSwipe = this.changeView.bind(this, viewTypes.SWIPE);
+    this.changeToViewOnionSkin = this.changeView.bind(this, viewTypes.ONION_SKIN);
+
+    this.viewModesEls[viewTypes.TWO_UP].addEventListener('click', this.changeToViewTwoUp);
+    this.viewModesEls[viewTypes.SWIPE].addEventListener('click', this.changeToViewSwipe);
+    this.viewModesEls[viewTypes.ONION_SKIN].addEventListener('click', this.changeToViewOnionSkin);
+  }
+
+  get imageEl() {
+    return this.imageEls[this.currentView];
+  }
+
+  get imageFrameEl() {
+    return this.imageFrameEls[this.currentView];
+  }
+
+  changeView(newView) {
+    if (!isValidViewType(newView)) {
+      return;
+    }
+
+    const indicator = imageDiffHelper.removeCommentIndicator(this.imageFrameEl);
+
+    this.currentView = newView;
+
+    // Clear existing badges on new view
+    const existingBadges = this.imageFrameEl.querySelectorAll('.badge');
+    [...existingBadges].map(badge => badge.remove());
+
+    // Remove existing references to old view image badges
+    this.imageBadges = [];
+
+    // Image_file.js has a fade animation of 200ms for loading the view
+    // Need to wait an additional 250ms for the images to be displayed
+    // on window in order to re-normalize their dimensions
+    setTimeout(this.renderNewView.bind(this, indicator), 250);
+  }
+
+  renderNewView(indicator) {
+    // Generate badge coordinates on new view
+    this.renderBadges();
+
+    // Re-render indicator in new view
+    if (indicator.removed) {
+      const normalizedIndicator = imageDiffHelper
+        .resizeCoordinatesToImageElement(this.imageEl, {
+          x: indicator.x,
+          y: indicator.y,
+          width: indicator.image.width,
+          height: indicator.image.height,
+        });
+      imageDiffHelper.showCommentIndicator(this.imageFrameEl, normalizedIndicator);
+    }
+  }
+}
diff --git a/app/assets/javascripts/image_diff/view_types.js b/app/assets/javascripts/image_diff/view_types.js
new file mode 100644
index 00000000000..ab0a595571f
--- /dev/null
+++ b/app/assets/javascripts/image_diff/view_types.js
@@ -0,0 +1,9 @@
+export const viewTypes = {
+  TWO_UP: 'TWO_UP',
+  SWIPE: 'SWIPE',
+  ONION_SKIN: 'ONION_SKIN',
+};
+
+export function isValidViewType(validate) {
+  return !!Object.getOwnPropertyNames(viewTypes).find(viewType => viewType === validate);
+}
diff --git a/app/assets/javascripts/lib/utils/image_utility.js b/app/assets/javascripts/lib/utils/image_utility.js
new file mode 100644
index 00000000000..2977ec821cb
--- /dev/null
+++ b/app/assets/javascripts/lib/utils/image_utility.js
@@ -0,0 +1,5 @@
+/* eslint-disable import/prefer-default-export */
+
+export function isImageLoaded(element) {
+  return element.complete && element.naturalHeight !== 0;
+}
diff --git a/app/assets/javascripts/main.js b/app/assets/javascripts/main.js
index 2c1dcc374ff..5858c2b6fd8 100644
--- a/app/assets/javascripts/main.js
+++ b/app/assets/javascripts/main.js
@@ -35,8 +35,6 @@ import './shortcuts_network';
 import './templates/issuable_template_selector';
 import './templates/issuable_template_selectors';
 
-// commit
-import './commit/file';
 import './commit/image_file';
 
 // lib/utils
@@ -70,7 +68,6 @@ import './build';
 import './build_artifacts';
 import './build_variables';
 import './ci_lint_editor';
-import './commit';
 import './commits';
 import './compare';
 import './compare_autocomplete';
diff --git a/app/assets/javascripts/merge_request_tabs.js b/app/assets/javascripts/merge_request_tabs.js
index d3299c15720..c042b22d1fd 100644
--- a/app/assets/javascripts/merge_request_tabs.js
+++ b/app/assets/javascripts/merge_request_tabs.js
@@ -13,6 +13,8 @@ import {
   isMetaClick,
 } from './lib/utils/common_utils';
 
+import initDiscussionTab from './image_diff/init_discussion_tab';
+
 /* eslint-disable max-len */
 // MergeRequestTabs
 //
@@ -154,6 +156,8 @@ import {
         }
         this.resetViewContainer();
         this.destroyPipelinesView();
+
+        initDiscussionTab();
       }
       if (this.setUrl) {
         this.setCurrentAction(action);
diff --git a/app/assets/javascripts/notes.js b/app/assets/javascripts/notes.js
index 93aa29454a0..24de21f2ce2 100644
--- a/app/assets/javascripts/notes.js
+++ b/app/assets/javascripts/notes.js
@@ -24,6 +24,7 @@ import './autosave';
 import './dropzone_input';
 import TaskList from './task_list';
 import { ajaxPost, isInViewport, getPagePath, scrollToElement, isMetaKey } from './lib/utils/common_utils';
+import imageDiffHelper from './image_diff/helpers/index';
 
 window.autosize = autosize;
 window.Dropzone = Dropzone;
@@ -42,6 +43,7 @@ export default class Notes {
     this.visibilityChange = this.visibilityChange.bind(this);
     this.cancelDiscussionForm = this.cancelDiscussionForm.bind(this);
     this.onAddDiffNote = this.onAddDiffNote.bind(this);
+    this.onAddImageDiffNote = this.onAddImageDiffNote.bind(this);
     this.setupDiscussionNoteForm = this.setupDiscussionNoteForm.bind(this);
     this.onReplyToDiscussionNote = this.onReplyToDiscussionNote.bind(this);
     this.removeNote = this.removeNote.bind(this);
@@ -114,6 +116,8 @@ export default class Notes {
     $(document).on('click', '.js-discussion-reply-button', this.onReplyToDiscussionNote);
     // add diff note
     $(document).on('click', '.js-add-diff-note-button', this.onAddDiffNote);
+    // add diff note for images
+    $(document).on('click', '.js-add-image-diff-note-button', this.onAddImageDiffNote);
     // hide diff note form
     $(document).on('click', '.js-close-discussion-note-form', this.cancelDiscussionForm);
     // toggle commit list
@@ -140,6 +144,7 @@ export default class Notes {
     $(document).off('click', '.js-note-attachment-delete');
     $(document).off('click', '.js-discussion-reply-button');
     $(document).off('click', '.js-add-diff-note-button');
+    $(document).off('click', '.js-add-image-diff-note-button');
     $(document).off('visibilitychange');
     $(document).off('keyup input', '.js-note-text');
     $(document).off('click', '.js-note-target-reopen');
@@ -412,6 +417,11 @@ export default class Notes {
     this.note_ids.push(noteEntity.id);
     form = $form || $(`.js-discussion-note-form[data-discussion-id="${noteEntity.discussion_id}"]`);
     row = form.closest('tr');
+
+    if (noteEntity.on_image) {
+      row = form;
+    }
+
     lineType = this.isParallelView() ? form.find('#line_type').val() : 'old';
     diffAvatarContainer = row.prevAll('.line_holder').first().find('.js-avatar-container.' + lineType + '_line');
     // is this the first note of discussion?
@@ -423,7 +433,7 @@ export default class Notes {
       if (noteEntity.diff_discussion_html) {
         var $discussion = $(noteEntity.diff_discussion_html).renderGFM();
 
-        if (!this.isParallelView() || row.hasClass('js-temp-notes-holder')) {
+        if (!this.isParallelView() || row.hasClass('js-temp-notes-holder') || noteEntity.on_image) {
           // insert the note and the reply button after the temp row
           row.after($discussion);
         } else {
@@ -449,6 +459,7 @@ export default class Notes {
 
     if (typeof gl.diffNotesCompileComponents !== 'undefined' && noteEntity.discussion_resolvable) {
       gl.diffNotesCompileComponents();
+
       this.renderDiscussionAvatar(diffAvatarContainer, noteEntity);
     }
 
@@ -561,7 +572,7 @@ export default class Notes {
       form.find('#note_line_code').val(),
 
       // DiffNote
-      form.find('#note_position').val()
+      form.find('#note_position').val(),
     ];
     return new Autosave(textarea, key);
   }
@@ -783,9 +794,22 @@ export default class Notes {
           $(`.js-diff-avatars-${discussionId}`).trigger('remove.vue');
 
           // The notes tr can contain multiple lists of notes, like on the parallel diff
-          if (notesTr.find('.discussion-notes').length > 1) {
+          // notesTr does not exist for image diffs
+          if (notesTr.find('.discussion-notes').length > 1 || notesTr.length === 0) {
+            const $diffFile = $notes.closest('.diff-file');
+            if ($diffFile.length > 0) {
+              const removeBadgeEvent = new CustomEvent('removeBadge.imageDiff', {
+                detail: {
+                  // badgeNumber's start with 1 and index starts with 0
+                  badgeNumber: $notes.index() + 1,
+                },
+              });
+
+              $diffFile[0].dispatchEvent(removeBadgeEvent);
+            }
+
             $notes.remove();
-          } else {
+          } else if (notesTr.length > 0) {
             notesTr.remove();
           }
         }
@@ -841,7 +865,11 @@ export default class Notes {
    */
   setupDiscussionNoteForm(dataHolder, form) {
     // setup note target
-    const diffFileData = dataHolder.closest('.text-file');
+    let diffFileData = dataHolder.closest('.text-file');
+
+    if (diffFileData.length === 0) {
+      diffFileData = dataHolder.closest('.image');
+    }
 
     var discussionID = dataHolder.data('discussionId');
 
@@ -907,6 +935,31 @@ export default class Notes {
     });
   }
 
+  onAddImageDiffNote(e) {
+    const $link = $(e.currentTarget || e.target);
+    const $diffFile = $link.closest('.diff-file');
+
+    const clickEvent = new CustomEvent('click.imageDiff', {
+      detail: e,
+    });
+
+    $diffFile[0].dispatchEvent(clickEvent);
+
+    // Setup comment form
+    let newForm;
+    const $noteContainer = $link.closest('.diff-viewer').find('.note-container');
+    const $form = $noteContainer.find('> .discussion-form');
+
+    if ($form.length === 0) {
+      newForm = this.cleanForm(this.formClone.clone());
+      newForm.appendTo($noteContainer);
+    } else {
+      newForm = $form;
+    }
+
+    this.setupDiscussionNoteForm($link, newForm);
+  }
+
   toggleDiffNote({
     target,
     lineType,
@@ -999,10 +1052,25 @@ export default class Notes {
   }
 
   cancelDiscussionForm(e) {
-    var form;
     e.preventDefault();
-    form = $(e.target).closest('.js-discussion-note-form');
-    return this.removeDiscussionNoteForm(form);
+    const $form = $(e.target).closest('.js-discussion-note-form');
+    const $discussionNote = $(e.target).closest('.discussion-notes');
+
+    if ($discussionNote.length === 0) {
+      // Only send blur event when the discussion form
+      // is not part of a discussion note
+      const $diffFile = $form.closest('.diff-file');
+
+      if ($diffFile.length > 0) {
+        const blurEvent = new CustomEvent('blur.imageDiff', {
+          detail: e,
+        });
+
+        $diffFile[0].dispatchEvent(blurEvent);
+      }
+    }
+
+    return this.removeDiscussionNoteForm($form);
   }
 
   /**
@@ -1414,6 +1482,15 @@ export default class Notes {
         // Submission successful! remove placeholder
         $notesContainer.find(`#${noteUniqueId}`).remove();
 
+        const $diffFile = $form.closest('.diff-file');
+        if ($diffFile.length > 0) {
+          const blurEvent = new CustomEvent('blur.imageDiff', {
+            detail: e,
+          });
+
+          $diffFile[0].dispatchEvent(blurEvent);
+        }
+
         // Reset cached commands list when command is applied
         if (hasQuickActions) {
           $form.find('textarea.js-note-text').trigger('clear-commands-cache.atwho');
@@ -1436,7 +1513,28 @@ export default class Notes {
           }
 
           // Show final note element on UI
-          this.addDiscussionNote($form, note, $notesContainer.length === 0);
+          const isNewDiffComment = $notesContainer.length === 0;
+          this.addDiscussionNote($form, note, isNewDiffComment);
+
+          if (isNewDiffComment) {
+            // Add image badge, avatar badge and toggle discussion badge for new image diffs
+            const notePosition = $form.find('#note_position').val();
+            if ($diffFile.length > 0 && notePosition.length > 0) {
+              const { x, y, width, height } = JSON.parse(notePosition);
+              const addBadgeEvent = new CustomEvent('addBadge.imageDiff', {
+                detail: {
+                  x,
+                  y,
+                  width,
+                  height,
+                  noteId: `note_${note.id}`,
+                  discussionId: note.discussion_id,
+                },
+              });
+
+              $diffFile[0].dispatchEvent(addBadgeEvent);
+            }
+          }
 
           // append flash-container to the Notes list
           if ($notesContainer.length) {
@@ -1457,6 +1555,16 @@ export default class Notes {
         // Submission failed, remove placeholder note and show Flash error message
         $notesContainer.find(`#${noteUniqueId}`).remove();
 
+        const blurEvent = new CustomEvent('blur.imageDiff', {
+          detail: e,
+        });
+
+        const closestDiffFile = $form.closest('.diff-file');
+
+        if (closestDiffFile.length) {
+          closestDiffFile[0].dispatchEvent(blurEvent);
+        }
+
         if (hasQuickActions) {
           $notesContainer.find(`#${systemNoteUniqueId}`).remove();
         }
@@ -1500,6 +1608,8 @@ export default class Notes {
     const $noteBody = $editingNote.find('.js-task-list-container');
     const $noteBodyText = $noteBody.find('.note-text');
     const { formData, formContent, formAction } = this.getFormData($form);
+    const $diffFile = $form.closest('.diff-file');
+    const $notesContainer = $form.closest('.notes');
 
     // Cache original comment content
     const cachedNoteBodyText = $noteBodyText.html();
diff --git a/app/assets/javascripts/single_file_diff.js b/app/assets/javascripts/single_file_diff.js
index 4505a79a2df..3f811c59cb9 100644
--- a/app/assets/javascripts/single_file_diff.js
+++ b/app/assets/javascripts/single_file_diff.js
@@ -1,6 +1,7 @@
 /* eslint-disable func-names, prefer-arrow-callback, space-before-function-paren, no-var, prefer-rest-params, wrap-iife, one-var, one-var-declaration-per-line, consistent-return, no-param-reassign, max-len */
 
 import FilesCommentButton from './files_comment_button';
+import imageDiffHelper from './image_diff/helpers/index';
 
 const WRAPPER = '<div class="diff-content"></div>';
 const LOADING_HTML = '<i class="fa fa-spinner fa-spin"></i>';
@@ -74,7 +75,11 @@ export default class SingleFileDiff {
           gl.diffNotesCompileComponents();
         }
 
-        FilesCommentButton.init($(_this.file));
+        const $file = $(_this.file);
+        FilesCommentButton.init($file);
+
+        const canCreateNote = $file.closest('.files').is('[data-can-create-note]');
+        imageDiffHelper.initImageDiff($file[0], canCreateNote);
 
         if (cb) cb();
       };
diff --git a/app/assets/stylesheets/framework/buttons.scss b/app/assets/stylesheets/framework/buttons.scss
index c77160a678b..b131e2d57ee 100644
--- a/app/assets/stylesheets/framework/buttons.scss
+++ b/app/assets/stylesheets/framework/buttons.scss
@@ -1,3 +1,25 @@
+@mixin btn-comment-icon {
+  border-radius: 50%;
+  background: $white-light;
+  padding: 1px 5px;
+  font-size: 12px;
+  color: $blue-500;
+  width: 23px;
+  height: 23px;
+  border: 1px solid $blue-500;
+
+  &:hover,
+  &.inverted {
+    background: $blue-500;
+    border-color: $blue-600;
+    color: $white-light;
+  }
+
+  &:active {
+    outline: 0;
+  }
+}
+
 @mixin btn-default {
   border-radius: 3px;
   font-size: $gl-font-size;
diff --git a/app/assets/stylesheets/framework/timeline.scss b/app/assets/stylesheets/framework/timeline.scss
index 3d68a50f91f..f718ec4bcad 100644
--- a/app/assets/stylesheets/framework/timeline.scss
+++ b/app/assets/stylesheets/framework/timeline.scss
@@ -17,15 +17,19 @@
 
   .diff-file {
     border: 1px solid $border-color;
-    border-bottom: none;
     margin: 0;
   }
+
+  &.text-file .diff-file {
+    border-bottom: none;
+  }
 }
 
 .timeline-entry {
   border-color: $white-normal;
   color: $gl-text-color;
   border-bottom: 1px solid $border-white-light;
+  background: $white-light;
 
   .timeline-entry-inner {
     position: relative;
diff --git a/app/assets/stylesheets/framework/variables.scss b/app/assets/stylesheets/framework/variables.scss
index 2f9def51d91..5f604680181 100644
--- a/app/assets/stylesheets/framework/variables.scss
+++ b/app/assets/stylesheets/framework/variables.scss
@@ -323,6 +323,7 @@ $diff-image-info-color: grey;
 $diff-swipe-border: #999;
 $diff-view-modes-color: grey;
 $diff-view-modes-border: #c1c1c1;
+$diff-jagged-border-gradient-color: darken($white-normal, 8%);
 
 /*
  * Fonts
@@ -712,3 +713,9 @@ Issuable warning
 */
 $issuable-warning-size: 24px;
 $issuable-warning-icon-margin: 4px;
+
+/*
+Image Commenting cursor
+*/
+$image-comment-cursor-left-offset: 12;
+$image-comment-cursor-top-offset: 30;
diff --git a/app/assets/stylesheets/pages/diff.scss b/app/assets/stylesheets/pages/diff.scss
index fb23343b966..ffb5fc94475 100644
--- a/app/assets/stylesheets/pages/diff.scss
+++ b/app/assets/stylesheets/pages/diff.scss
@@ -297,6 +297,7 @@
         .drag-track {
           display: block;
           position: absolute;
+          top: 0;
           left: 12px;
           height: 10px;
           width: 276px;
@@ -547,16 +548,23 @@
 }
 
 .diff-notes-collapse {
-  width: 19px;
-  height: 19px;
+  width: 24px;
+  height: 24px;
+  border-radius: 50%;
   padding: 0;
   transition: transform .1s ease-out;
   z-index: 100;
 
+  .collapse-icon {
+    height: 50%;
+    width: 100%;
+  }
+
   svg {
-    vertical-align: text-top;
+    vertical-align: middle;
   }
 
+  .collapse-icon,
   path {
     fill: $white-light;
   }
@@ -644,3 +652,157 @@
   text-overflow: ellipsis;
   white-space: nowrap;
 }
+
+.note-container {
+  background-color: $gray-light;
+  border-top: 1px solid $white-normal;
+
+  // double jagged line divider
+  .discussion-notes + .discussion-notes::before,
+  .discussion-notes + .discussion-form::before {
+    content: '';
+    position: relative;
+    display: block;
+    width: 100%;
+    height: 10px;
+    background-color: $white-light;
+    background-image: linear-gradient(45deg, transparent, transparent 73%, $diff-jagged-border-gradient-color 75%, $white-light 80%),
+      linear-gradient(225deg, transparent, transparent 73%, $diff-jagged-border-gradient-color 75%, $white-light 80%),
+      linear-gradient(135deg, transparent, transparent 73%, $diff-jagged-border-gradient-color 75%, $white-light 80%),
+      linear-gradient(-45deg, transparent, transparent 73%, $diff-jagged-border-gradient-color 75%, $white-light 80%);
+    background-position: 5px 5px,0 5px,0 5px,5px 5px;
+    background-size: 10px 10px;
+    background-repeat: repeat;
+  }
+
+  .notes {
+    position: relative;
+  }
+
+  .diff-notes-collapse {
+    position: absolute;
+    left: -12px;
+  }
+}
+
+.diff-file .note-container > .new-note,
+.note-container .discussion-notes {
+  margin-left: 100px;
+  border-left: 1px solid $white-normal;
+}
+
+.notes.active {
+  .diff-file .note-container > .new-note,
+  .note-container .discussion-notes {
+    // Override our margin and border (set for diff tab)
+    // when user is on the discussion tab for MR
+    margin-left: inherit;
+    border-left: inherit;
+  }
+}
+
+.files:not([data-can-create-note]) .frame {
+  cursor: auto;
+}
+
+.frame.click-to-comment {
+  position: relative;
+  cursor: url(icon_image_comment.svg)
+    $image-comment-cursor-left-offset $image-comment-cursor-top-offset, auto;
+
+  // Retina cursor
+  cursor: -webkit-image-set(url(icon_image_comment.svg) 1x, url(icon_image_comment@2x.svg) 2x)
+    $image-comment-cursor-left-offset $image-comment-cursor-top-offset, auto;
+
+  .comment-indicator {
+    position: absolute;
+    padding: 0;
+    width: (2px * $image-comment-cursor-left-offset);
+    height: (1px * $image-comment-cursor-top-offset);
+    // center the indicator to match the top left click region
+    margin-top: (-1px * $image-comment-cursor-top-offset) + 2;
+    margin-left: (-1px * $image-comment-cursor-left-offset) + 1;
+
+    svg {
+      width: 100%;
+      height: 100%;
+    }
+
+    &:focus {
+      outline: none;
+    }
+  }
+}
+
+.frame .badge,
+.image-diff-avatar-link .badge,
+.notes > .badge {
+  position: absolute;
+  background-color: $blue-400;
+  color: $white-light;
+  border: $white-light 1px solid;
+  min-height: $gl-padding;
+  padding: 5px 8px;
+  border-radius: 12px;
+
+  &:focus {
+    outline: none;
+  }
+}
+
+.frame .badge,
+.frame .image-comment-badge {
+  // Center align badges on the frame
+  transform: translate3d(-50%, -50%, 0);
+}
+
+.image-comment-badge {
+  @include btn-comment-icon;
+  position: absolute;
+
+  &.inverted {
+    border-color: $white-light;
+  }
+}
+
+.image-diff-avatar-link {
+  position: relative;
+
+  .badge,
+  .image-comment-badge {
+    top: 25px;
+    right: 8px;
+  }
+}
+
+.notes > .badge {
+  display: none;
+  left: -13px;
+}
+
+.discussion-notes {
+  min-height: 35px;
+
+  &:first-child {
+    // First child does not have the jagged borders
+    min-height: 25px;
+  }
+
+  &.collapsed {
+    background-color: $white-light;
+
+    .diff-notes-collapse,
+    .note,
+    .discussion-reply-holder, {
+      display: none;
+    }
+
+    .notes > .badge {
+      display: block;
+    }
+  }
+}
+
+.discussion-body .image .frame {
+  position: relative;
+}
diff --git a/app/assets/stylesheets/pages/note_form.scss b/app/assets/stylesheets/pages/note_form.scss
index 420bca9ece5..04b132415eb 100644
--- a/app/assets/stylesheets/pages/note_form.scss
+++ b/app/assets/stylesheets/pages/note_form.scss
@@ -161,10 +161,13 @@
 }
 
 .discussion-form {
-  padding: $gl-padding-top $gl-padding $gl-padding;
   background-color: $white-light;
 }
 
+.discussion-form-container {
+  padding: $gl-padding-top $gl-padding $gl-padding;
+}
+
 .discussion-notes .disabled-comment {
   padding: 6px 0;
 }
diff --git a/app/assets/stylesheets/pages/notes.scss b/app/assets/stylesheets/pages/notes.scss
index 925fe4513ee..96b7db3b85d 100644
--- a/app/assets/stylesheets/pages/notes.scss
+++ b/app/assets/stylesheets/pages/notes.scss
@@ -650,29 +650,12 @@ ul.notes {
 }
 
 .add-diff-note {
+  @include btn-comment-icon;
   opacity: 0;
   margin-top: -2px;
-  border-radius: 50%;
-  background: $white-light;
-  padding: 1px 5px;
-  font-size: 12px;
-  color: $blue-500;
   margin-left: -55px;
   position: absolute;
   z-index: 10;
-  width: 23px;
-  height: 23px;
-  border: 1px solid $blue-500;
-
-  &:hover {
-    background: $blue-500;
-    border-color: $blue-600;
-    color: $white-light;
-  }
-
-  &:active {
-    outline: 0;
-  }
 }
 
 .discussion-body,
diff --git a/app/controllers/concerns/notes_actions.rb b/app/controllers/concerns/notes_actions.rb
index 915f32b4c33..1126f706393 100644
--- a/app/controllers/concerns/notes_actions.rb
+++ b/app/controllers/concerns/notes_actions.rb
@@ -96,7 +96,8 @@ module NotesActions
           id: note.id,
           discussion_id: note.discussion_id(noteable),
           html: note_html(note),
-          note: note.note
+          note: note.note,
+          on_image: note.try(:on_image?)
         )
 
         discussion = note.to_discussion(noteable)
@@ -122,7 +123,9 @@ module NotesActions
   def diff_discussion_html(discussion)
     return unless discussion.diff_discussion?
 
-    if params[:view] == 'parallel'
+    on_image = discussion.on_image?
+
+    if params[:view] == 'parallel' && !on_image
       template = "discussions/_parallel_diff_discussion"
       locals =
         if params[:line_type] == 'old'
@@ -132,7 +135,9 @@ module NotesActions
         end
     else
       template = "discussions/_diff_discussion"
-      locals = { discussions: [discussion] }
+      @fresh_discussion = true
+
+      locals = { discussions: [discussion], on_image: on_image }
     end
 
     render_to_string(
diff --git a/app/models/concerns/discussion_on_diff.rb b/app/models/concerns/discussion_on_diff.rb
index eee1a36ac6b..f5cbb3becad 100644
--- a/app/models/concerns/discussion_on_diff.rb
+++ b/app/models/concerns/discussion_on_diff.rb
@@ -28,6 +28,10 @@ module DiscussionOnDiff
     true
   end
 
+  def file_new_path
+    first_note.position.new_path
+  end
+
   # Returns an array of at most 16 highlighted lines above a diff note
   def truncated_diff_lines(highlight: true)
     lines = highlight ? highlighted_diff_lines : diff_lines
diff --git a/app/models/diff_discussion.rb b/app/models/diff_discussion.rb
index 07c4846e2ac..6eba87da1a1 100644
--- a/app/models/diff_discussion.rb
+++ b/app/models/diff_discussion.rb
@@ -11,6 +11,8 @@ class DiffDiscussion < Discussion
   delegate  :position,
             :original_position,
             :change_position,
+            :on_text?,
+            :on_image?,
 
             to: :first_note
 
diff --git a/app/models/diff_note.rb b/app/models/diff_note.rb
index e9a60e6ce09..d88a92dc027 100644
--- a/app/models/diff_note.rb
+++ b/app/models/diff_note.rb
@@ -12,8 +12,8 @@ class DiffNote < Note
 
   validates :original_position, presence: true
   validates :position, presence: true
-  validates :diff_line, presence: true
-  validates :line_code, presence: true, line_code: true
+  validates :diff_line, presence: true, if: :on_text?
+  validates :line_code, presence: true, line_code: true, if: :on_text?
   validates :noteable_type, inclusion: { in: NOTEABLE_TYPES }
   validate :positions_complete
   validate :verify_supported
@@ -43,6 +43,14 @@ class DiffNote < Note
     end
   end
 
+  def on_text?
+    position.position_type == "text"
+  end
+
+  def on_image?
+    position.position_type == "image"
+  end
+
   def diff_file
     @diff_file ||= self.original_position.diff_file(self.project.repository)
   end
@@ -56,6 +64,8 @@ class DiffNote < Note
   end
 
   def original_line_code
+    return unless on_text?
+
     self.diff_file.line_code(self.diff_line)
   end
 
diff --git a/app/models/discussion.rb b/app/models/discussion.rb
index b80da7b246a..437df923d2d 100644
--- a/app/models/discussion.rb
+++ b/app/models/discussion.rb
@@ -66,6 +66,10 @@ class Discussion
     @context_noteable = context_noteable
   end
 
+  def on_image?
+    false
+  end
+
   def ==(other)
     other.class == self.class &&
       other.context_noteable == self.context_noteable &&
diff --git a/app/models/legacy_diff_discussion.rb b/app/models/legacy_diff_discussion.rb
index 3c1d34db5fa..80fc6304fd4 100644
--- a/app/models/legacy_diff_discussion.rb
+++ b/app/models/legacy_diff_discussion.rb
@@ -17,6 +17,14 @@ class LegacyDiffDiscussion < Discussion
     true
   end
 
+  def on_image?
+    false
+  end
+
+  def on_text?
+    true
+  end
+
   def active?(*args)
     return @active if @active.present?
 
diff --git a/app/models/note.rb b/app/models/note.rb
index f44590e2144..ceded9f2aef 100644
--- a/app/models/note.rb
+++ b/app/models/note.rb
@@ -134,14 +134,22 @@ class Note < ActiveRecord::Base
       Discussion.build(notes)
     end
 
+    # Group diff discussions by line code or file path.
+    # It is not needed to group by line code when comment is
+    # on an image.
     def grouped_diff_discussions(diff_refs = nil)
       groups = {}
 
       diff_notes.fresh.discussions.each do |discussion|
-        line_code = discussion.line_code_in_diffs(diff_refs)
-
-        if line_code
-          discussions = groups[line_code] ||= []
+        group_key =
+          if discussion.on_image?
+            discussion.file_new_path
+          else
+            discussion.line_code_in_diffs(diff_refs)
+          end
+
+        if group_key
+          discussions = groups[group_key] ||= []
           discussions << discussion
         end
       end
diff --git a/app/views/discussions/_diff_discussion.html.haml b/app/views/discussions/_diff_discussion.html.haml
index e6d307e5568..52279d0a870 100644
--- a/app/views/discussions/_diff_discussion.html.haml
+++ b/app/views/discussions/_diff_discussion.html.haml
@@ -1,6 +1,10 @@
-- expanded = local_assigns.fetch(:expanded, true)
-%tr.notes_holder{ class: ('hide' unless expanded) }
-  %td.notes_line{ colspan: 2 }
-  %td.notes_content
-    .content{ class: ('hide' unless expanded) }
-      = render partial: "discussions/notes", collection: discussions, as: :discussion
+- if local_assigns[:on_image]
+  = render partial: "discussions/notes", collection: discussions, as: :discussion
+- else
+  -# Text diff discussions
+  - expanded = local_assigns.fetch(:expanded, true)
+  %tr.notes_holder{ class: ('hide' unless expanded) }
+    %td.notes_line{ colspan: 2 }
+    %td.notes_content
+      .content{ class: ('hide' unless expanded) }
+        = render partial: "discussions/notes", collection: discussions, as: :discussion
diff --git a/app/views/discussions/_diff_with_notes.html.haml b/app/views/discussions/_diff_with_notes.html.haml
index 4a41be972da..636d06cab53 100644
--- a/app/views/discussions/_diff_with_notes.html.haml
+++ b/app/views/discussions/_diff_with_notes.html.haml
@@ -1,18 +1,27 @@
 - diff_file = discussion.diff_file
 - blob = discussion.blob
+- discussions = { discussion.original_line_code => [discussion] }
+- diff_file_class = diff_file.text? ? 'text-file' : 'js-image-file'
 
-.diff-file.file-holder
+.diff-file.file-holder{ class: diff_file_class }
   .js-file-title.file-title.file-title-flex-parent
     .file-header-content
       = render "projects/diffs/file_header", diff_file: diff_file, url: discussion_path(discussion), show_toggle: false
 
-  .diff-content.code.js-syntax-highlight
-    %table
-      - discussions = { discussion.original_line_code => [discussion] }
-      = render partial: "projects/diffs/line",
-        collection: discussion.truncated_diff_lines,
-        as: :line,
-        locals: { diff_file: diff_file,
-          discussions: discussions,
-          discussion_expanded: true,
-          plain: true }
+  - if diff_file.text?
+    .diff-content.code.js-syntax-highlight
+      %table
+        = render partial: "projects/diffs/line",
+          collection: discussion.truncated_diff_lines,
+          as: :line,
+          locals: { diff_file: diff_file,
+            discussions: discussions,
+            discussion_expanded: true,
+            plain: true }
+  - else
+    - partial = (diff_file.new_file? || diff_file.deleted_file?) ? 'single_image_diff' : 'replaced_image_diff'
+
+    = render partial: "projects/diffs/#{partial}", locals: { diff_file: diff_file, position: discussion.position.to_json, click_to_comment: false }
+
+    .note-container
+      = render partial: "discussions/notes", locals: { discussion: discussion, show_toggle: false, show_image_comment_badge: true, disable_collapse: true }
diff --git a/app/views/discussions/_notes.html.haml b/app/views/discussions/_notes.html.haml
index db5ab939948..9efcfef690f 100644
--- a/app/views/discussions/_notes.html.haml
+++ b/app/views/discussions/_notes.html.haml
@@ -1,6 +1,19 @@
-.discussion-notes
-  %ul.notes{ data: { discussion_id: discussion.id } }
-    = render partial: "shared/notes/note", collection: discussion.notes, as: :note
+- disable_collapse = local_assigns.fetch(:disable_collapse, false)
+- collapsed_class = 'collapsed' if discussion.resolved? && !disable_collapse
+- badge_counter = discussion_counter + 1 if local_assigns[:discussion_counter]
+- show_toggle = local_assigns.fetch(:show_toggle, true)
+- show_image_comment_badge = local_assigns.fetch(:show_image_comment_badge, false)
+
+.discussion-notes{ class: collapsed_class }
+  -# Save the first note position data so that we have a reference and can go
+  -# to the first note position when we click on a badge diff discussion
+  %ul.notes{ id: "discussion_#{discussion.id}", data: { discussion_id: discussion.id, position: discussion.notes[0].position.to_json } }
+    - if discussion.try(:on_image?) && show_toggle
+      %button.diff-notes-collapse.js-diff-notes-toggle{ type: 'button' }
+        = sprite_icon('collapse', css_class: 'collapse-icon')
+      %button.btn-transparent.badge.js-diff-notes-toggle{ type: 'button' }
+        = badge_counter
+    = render partial: "shared/notes/note", collection: discussion.notes, as: :note, locals: { badge_counter: badge_counter, show_image_comment_badge: show_image_comment_badge }
 
   .flash-container
 
diff --git a/app/views/projects/diffs/_image_diff_frame.html.haml b/app/views/projects/diffs/_image_diff_frame.html.haml
new file mode 100644
index 00000000000..dae73e10460
--- /dev/null
+++ b/app/views/projects/diffs/_image_diff_frame.html.haml
@@ -0,0 +1,5 @@
+- class_name = local_assigns.fetch(:class_name, '')
+- note_type = local_assigns.fetch(:note_type, '')
+
+.frame{ class: class_name, data: { position: position, note_type: note_type } }
+  = image_tag(image_path, alt: alt, draggable: false, lazy: false)
diff --git a/app/views/projects/diffs/_replaced_image_diff.html.haml b/app/views/projects/diffs/_replaced_image_diff.html.haml
new file mode 100644
index 00000000000..8fc232b464e
--- /dev/null
+++ b/app/views/projects/diffs/_replaced_image_diff.html.haml
@@ -0,0 +1,61 @@
+- blob = diff_file.blob
+- old_blob = diff_file.old_blob
+- blob_raw_path = diff_file_blob_raw_path(diff_file)
+- old_blob_raw_path = diff_file_old_blob_raw_path(diff_file)
+- click_to_comment = local_assigns.fetch(:click_to_comment, true)
+- diff_view_data = local_assigns.fetch(:diff_view_data, '')
+- class_name = ''
+
+- if click_to_comment
+  - class_name = 'js-add-image-diff-note-button click-to-comment'
+
+.image.js-replaced-image{ data: diff_view_data }
+  .two-up.view
+    .wrap
+      .frame.deleted
+        = image_tag(old_blob_raw_path, alt: diff_file.old_path, lazy: false)
+      %p.image-info.hide
+        %span.meta-filesize= number_to_human_size(old_blob.size)
+        |
+        %strong W:
+        %span.meta-width
+        |
+        %strong H:
+        %span.meta-height
+    .wrap
+      = render partial: "projects/diffs/image_diff_frame", locals: { class_name: "added js-image-frame #{class_name}", position: position, note_type: DiffNote.name, image_path: blob_raw_path, alt: diff_file.new_path }
+      %p.image-info.hide
+        %span.meta-filesize= number_to_human_size(blob.size)
+        |
+        %strong W:
+        %span.meta-width
+        |
+        %strong H:
+        %span.meta-height
+
+  .swipe.view.hide
+    .swipe-frame
+      .frame.deleted
+        = image_tag(old_blob_raw_path, alt: diff_file.old_path, lazy: false)
+      .swipe-wrap
+        = render partial: "projects/diffs/image_diff_frame", locals: { class_name: "added js-image-frame #{class_name}", position: position, note_type: DiffNote.name, image_path: blob_raw_path, alt: diff_file.new_path }
+      %span.swipe-bar
+        %span.top-handle
+        %span.bottom-handle
+
+  .onion-skin.view.hide
+    .onion-skin-frame
+      .frame.deleted
+        = image_tag(old_blob_raw_path, alt: diff_file.old_path, lazy: false)
+      = render partial: "projects/diffs/image_diff_frame", locals: { class_name: "added js-image-frame #{class_name}", position: position, note_type: DiffNote.name, image_path: blob_raw_path, alt: diff_file.new_path }
+      .controls
+        .transparent
+        .drag-track
+          .dragger{ :style => "left: 0px;" }
+        .opaque
+
+.view-modes.hide
+  %ul.view-modes-menu
+    %li.two-up{ data: { mode: 'two-up' } } 2-up
+    %li.swipe{ data: { mode: 'swipe' } } Swipe
+    %li.onion-skin{ data: { mode: 'onion-skin' } } Onion skin
diff --git a/app/views/projects/diffs/_single_image_diff.html.haml b/app/views/projects/diffs/_single_image_diff.html.haml
new file mode 100644
index 00000000000..6b0c6bbe48f
--- /dev/null
+++ b/app/views/projects/diffs/_single_image_diff.html.haml
@@ -0,0 +1,16 @@
+- blob = diff_file.blob
+- old_blob = diff_file.old_blob
+- blob_raw_path = diff_file_blob_raw_path(diff_file)
+- old_blob_raw_path = diff_file_old_blob_raw_path(diff_file)
+- click_to_comment = local_assigns.fetch(:click_to_comment, true)
+- diff_view_data = local_assigns.fetch(:diff_view_data, '')
+- class_name = ''
+
+- if click_to_comment
+  - class_name = 'js-add-image-diff-note-button click-to-comment'
+
+.image.js-single-image{ data: diff_view_data }
+  .wrap
+    - single_class_name = diff_file.deleted_file? ? 'deleted' : 'added'
+    = render partial: "projects/diffs/image_diff_frame", locals: { class_name: "#{single_class_name} #{class_name} js-image-frame", position: position, note_type: DiffNote.name, image_path: blob_raw_path, alt: diff_file.file_path }
+  %p.image-info= number_to_human_size(blob.size)
diff --git a/app/views/projects/diffs/viewers/_image.html.haml b/app/views/projects/diffs/viewers/_image.html.haml
index 6b5233833c6..f190073c2fc 100644
--- a/app/views/projects/diffs/viewers/_image.html.haml
+++ b/app/views/projects/diffs/viewers/_image.html.haml
@@ -1,67 +1,13 @@
 - diff_file = viewer.diff_file
-- blob = diff_file.blob
-- old_blob = diff_file.old_blob
-- blob_raw_path = diff_file_blob_raw_path(diff_file)
-- old_blob_raw_path = diff_file_old_blob_raw_path(diff_file)
+- image_point = Gitlab::Diff::ImagePoint.new(nil, nil, nil, nil)
+- discussions = @grouped_diff_discussions[diff_file.new_path] if @grouped_diff_discussions
+
+- locals = { diff_file: diff_file, position: diff_file.position(image_point, position_type: :image).to_json, click_to_comment: true, diff_view_data: diff_view_data }
 
 - if diff_file.new_file? || diff_file.deleted_file?
-  .image
-    %span.wrap
-      .frame{ class: (diff_file.deleted_file? ? 'deleted' : 'added') }
-        = image_tag(blob_raw_path, alt: diff_file.file_path)
-      %p.image-info= number_to_human_size(blob.size)
+  = render partial: "projects/diffs/single_image_diff", locals: locals
 - else
-  .image
-    .two-up.view
-      %span.wrap
-        .frame.deleted
-          = image_tag(old_blob_raw_path, alt: diff_file.old_path)
-        %p.image-info.hide
-          %span.meta-filesize= number_to_human_size(old_blob.size)
-          |
-          %b W:
-          %span.meta-width
-          |
-          %b H:
-          %span.meta-height
-      %span.wrap
-        .frame.added
-          = image_tag(blob_raw_path, alt: diff_file.new_path)
-        %p.image-info.hide
-          %span.meta-filesize= number_to_human_size(blob.size)
-          |
-          %b W:
-          %span.meta-width
-          |
-          %b H:
-          %span.meta-height
-
-    .swipe.view.hide
-      .swipe-frame
-        .frame.deleted
-          = image_tag(old_blob_raw_path, alt: diff_file.old_path, lazy: false)
-        .swipe-wrap
-          .frame.added
-            = image_tag(blob_raw_path, alt: diff_file.new_path, lazy: false)
-        %span.swipe-bar
-          %span.top-handle
-          %span.bottom-handle
-
-    .onion-skin.view.hide
-      .onion-skin-frame
-        .frame.deleted
-          = image_tag(old_blob_raw_path, alt: diff_file.old_path, lazy: false)
-        .frame.added
-          = image_tag(blob_raw_path, alt: diff_file.new_path, lazy: false)
-        .controls
-          .transparent
-          .drag-track
-            .dragger{ :style => "left: 0px;" }
-          .opaque
-
+  = render partial: "projects/diffs/replaced_image_diff", locals: locals
 
-  .view-modes.hide
-    %ul.view-modes-menu
-      %li.two-up{ data: { mode: 'two-up' } } 2-up
-      %li.swipe{ data: { mode: 'swipe' } } Swipe
-      %li.onion-skin{ data: { mode: 'onion-skin' } } Onion skin
+.note-container
+  = render partial: "discussions/notes", collection: discussions, as: :discussion
diff --git a/app/views/shared/notes/_form.html.haml b/app/views/shared/notes/_form.html.haml
index 725bf916592..71c0d740bc8 100644
--- a/app/views/shared/notes/_form.html.haml
+++ b/app/views/shared/notes/_form.html.haml
@@ -24,20 +24,21 @@
   -# DiffNote
   = f.hidden_field :position
 
-  = render layout: 'projects/md_preview', locals: { url: preview_url, referenced_users: true } do
-    = render 'projects/zen', f: f,
-      attr: :note,
-      classes: 'note-textarea js-note-text',
-      placeholder: "Write a comment or drag your files here...",
-      supports_quick_actions: supports_quick_actions,
-      supports_autocomplete: supports_autocomplete
-    = render 'shared/notes/hints', supports_quick_actions: supports_quick_actions
-    .error-alert
-
-  .note-form-actions.clearfix
-    = render partial: 'shared/notes/comment_button'
-
-    = yield(:note_actions)
-
-    %a.btn.btn-cancel.js-note-discard{ role: "button", data: {cancel_text: "Cancel" } }
-      Discard draft
+  .discussion-form-container
+    = render layout: 'projects/md_preview', locals: { url: preview_url, referenced_users: true } do
+      = render 'projects/zen', f: f,
+        attr: :note,
+        classes: 'note-textarea js-note-text',
+        placeholder: "Write a comment or drag your files here...",
+        supports_quick_actions: supports_quick_actions,
+        supports_autocomplete: supports_autocomplete
+      = render 'shared/notes/hints', supports_quick_actions: supports_quick_actions
+      .error-alert
+
+    .note-form-actions.clearfix
+      = render partial: 'shared/notes/comment_button'
+
+      = yield(:note_actions)
+
+      %a.btn.btn-cancel.js-note-discard{ role: "button", data: {cancel_text: "Cancel" } }
+        Discard draft
diff --git a/app/views/shared/notes/_note.html.haml b/app/views/shared/notes/_note.html.haml
index 4f00a9f2759..b6085fd3af0 100644
--- a/app/views/shared/notes/_note.html.haml
+++ b/app/views/shared/notes/_note.html.haml
@@ -1,7 +1,10 @@
 - return unless note.author
 - return if note.cross_reference_not_visible_for?(current_user)
 
+- show_image_comment_badge = local_assigns.fetch(:show_image_comment_badge, false)
 - note_editable = note_editable?(note)
+- note_counter = local_assigns.fetch(:note_counter, 0)
+
 %li.timeline-entry{ id: dom_id(note),
   class: ["note", "note-row-#{note.id}", ('system-note' if note.system)],
   data: { author_id: note.author.id,
@@ -12,8 +15,18 @@
       - if note.system
         = icon_for_system_note(note)
       - else
-        %a{ href: user_path(note.author) }
+        %a.image-diff-avatar-link{ href: user_path(note.author) }
           = image_tag avatar_icon(note.author), alt: '', class: 'avatar s40'
+          - if note.is_a?(DiffNote) && note.on_image?
+            - if show_image_comment_badge && note_counter == 0
+              -# Only show this for the first comment in the discussion
+              %span.image-comment-badge.inverted
+                = icon('comment-o')
+            - elsif note_counter == 0
+              - counter = badge_counter if local_assigns[:badge_counter]
+              - badge_class = "hidden" if @fresh_discussion || counter.nil?
+              %span.badge{ class: badge_class }
+                = counter
     .timeline-content
       .note-header
         .note-header-info
diff --git a/changelogs/unreleased/issue_35873.yml b/changelogs/unreleased/issue_35873.yml
new file mode 100644
index 00000000000..65064b97e56
--- /dev/null
+++ b/changelogs/unreleased/issue_35873.yml
@@ -0,0 +1,5 @@
+---
+title: Commenting on image diffs
+merge_request: 14061
+author:
+type: added
diff --git a/lib/gitlab/diff/file.rb b/lib/gitlab/diff/file.rb
index fcac85ff892..599c3c5deab 100644
--- a/lib/gitlab/diff/file.rb
+++ b/lib/gitlab/diff/file.rb
@@ -27,16 +27,23 @@ module Gitlab
         @fallback_diff_refs = fallback_diff_refs
       end
 
-      def position(line)
+      def position(position_marker, position_type: :text)
         return unless diff_refs
 
-        Position.new(
+        data = {
+          diff_refs: diff_refs,
+          position_type: position_type.to_s,
           old_path: old_path,
-          new_path: new_path,
-          old_line: line.old_line,
-          new_line: line.new_line,
-          diff_refs: diff_refs
-        )
+          new_path: new_path
+        }
+
+        if position_type == :text
+          data.merge!(text_position_properties(position_marker))
+        else
+          data.merge!(image_position_properties(position_marker))
+        end
+
+        Position.new(data)
       end
 
       def line_code(line)
@@ -228,6 +235,14 @@ module Gitlab
 
       private
 
+      def text_position_properties(line)
+        { old_line: line.old_line, new_line: line.new_line }
+      end
+
+      def image_position_properties(image_point)
+        image_point.to_h
+      end
+
       def blobs_changed?
         old_blob && new_blob && old_blob.id != new_blob.id
       end
diff --git a/lib/gitlab/diff/formatters/base_formatter.rb b/lib/gitlab/diff/formatters/base_formatter.rb
new file mode 100644
index 00000000000..5e923b9e602
--- /dev/null
+++ b/lib/gitlab/diff/formatters/base_formatter.rb
@@ -0,0 +1,61 @@
+module Gitlab
+  module Diff
+    module Formatters
+      class BaseFormatter
+        attr_reader :old_path
+        attr_reader :new_path
+        attr_reader :base_sha
+        attr_reader :start_sha
+        attr_reader :head_sha
+        attr_reader :position_type
+
+        def initialize(attrs)
+          if diff_file = attrs[:diff_file]
+            attrs[:diff_refs] = diff_file.diff_refs
+            attrs[:old_path] = diff_file.old_path
+            attrs[:new_path] = diff_file.new_path
+          end
+
+          if diff_refs = attrs[:diff_refs]
+            attrs[:base_sha] = diff_refs.base_sha
+            attrs[:start_sha] = diff_refs.start_sha
+            attrs[:head_sha]  = diff_refs.head_sha
+          end
+
+          @old_path = attrs[:old_path]
+          @new_path = attrs[:new_path]
+          @base_sha = attrs[:base_sha]
+          @start_sha = attrs[:start_sha]
+          @head_sha  = attrs[:head_sha]
+        end
+
+        def key
+          [base_sha, start_sha, head_sha, Digest::SHA1.hexdigest(old_path || ""), Digest::SHA1.hexdigest(new_path || "")]
+        end
+
+        def to_h
+          {
+            base_sha: base_sha,
+            start_sha: start_sha,
+            head_sha: head_sha,
+            old_path: old_path,
+            new_path: new_path,
+            position_type: position_type
+          }
+        end
+
+        def position_type
+          raise NotImplementedError
+        end
+
+        def ==(other)
+          raise NotImplementedError
+        end
+
+        def complete?
+          raise NotImplementedError
+        end
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/diff/formatters/image_formatter.rb b/lib/gitlab/diff/formatters/image_formatter.rb
new file mode 100644
index 00000000000..ccd0d309972
--- /dev/null
+++ b/lib/gitlab/diff/formatters/image_formatter.rb
@@ -0,0 +1,43 @@
+module Gitlab
+  module Diff
+    module Formatters
+      class ImageFormatter < BaseFormatter
+        attr_reader :width
+        attr_reader :height
+        attr_reader :x
+        attr_reader :y
+
+        def initialize(attrs)
+          @x = attrs[:x]
+          @y = attrs[:y]
+          @width = attrs[:width]
+          @height = attrs[:height]
+
+          super(attrs)
+        end
+
+        def key
+          @key ||= super.push(x, y)
+        end
+
+        def complete?
+          x && y && width && height
+        end
+
+        def to_h
+          super.merge(width: width, height: height, x: x, y: y)
+        end
+
+        def position_type
+          "image"
+        end
+
+        def ==(other)
+          other.is_a?(self.class) &&
+            x == other.x &&
+            y == other.y
+        end
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/diff/formatters/text_formatter.rb b/lib/gitlab/diff/formatters/text_formatter.rb
new file mode 100644
index 00000000000..01c7e9f51ab
--- /dev/null
+++ b/lib/gitlab/diff/formatters/text_formatter.rb
@@ -0,0 +1,49 @@
+module Gitlab
+  module Diff
+    module Formatters
+      class TextFormatter < BaseFormatter
+        attr_reader :old_line
+        attr_reader :new_line
+
+        def initialize(attrs)
+          @old_line = attrs[:old_line]
+          @new_line = attrs[:new_line]
+
+          super(attrs)
+        end
+
+        def key
+          @key ||= super.push(old_line, new_line)
+        end
+
+        def complete?
+          old_line || new_line
+        end
+
+        def to_h
+          super.merge(old_line: old_line, new_line: new_line)
+        end
+
+        def line_age
+          if old_line && new_line
+            nil
+          elsif new_line
+            'new'
+          else
+            'old'
+          end
+        end
+
+        def position_type
+          "text"
+        end
+
+        def ==(other)
+          other.is_a?(self.class) &&
+            new_line == other.new_line &&
+            old_line == other.old_line
+        end
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/diff/image_point.rb b/lib/gitlab/diff/image_point.rb
new file mode 100644
index 00000000000..65332dfd239
--- /dev/null
+++ b/lib/gitlab/diff/image_point.rb
@@ -0,0 +1,23 @@
+module Gitlab
+  module Diff
+    class ImagePoint
+      attr_reader :width, :height, :x, :y
+
+      def initialize(width, height, x, y)
+        @width = width
+        @height = height
+        @x = x
+        @y = y
+      end
+
+      def to_h
+        {
+          width: width,
+          height: height,
+          x: x,
+          y: y
+        }
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/diff/position.rb b/lib/gitlab/diff/position.rb
index b8db3adef0a..bd0a9502a5e 100644
--- a/lib/gitlab/diff/position.rb
+++ b/lib/gitlab/diff/position.rb
@@ -1,37 +1,25 @@
-# Defines a specific location, identified by paths and line numbers,
+# Defines a specific location, identified by paths line numbers and image coordinates,
 # within a specific diff, identified by start, head and base commit ids.
 module Gitlab
   module Diff
     class Position
-      attr_reader :old_path
-      attr_reader :new_path
-      attr_reader :old_line
-      attr_reader :new_line
-      attr_reader :base_sha
-      attr_reader :start_sha
-      attr_reader :head_sha
-
+      attr_accessor :formatter
+
+      delegate :old_path,
+               :new_path,
+               :base_sha,
+               :start_sha,
+               :head_sha,
+               :old_line,
+               :new_line,
+               :position_type, to: :formatter
+
+      # A position can belong to a text line or to an image coordinate
+      # it depends of the position_type argument.
+      # Text position will have: new_line and old_line
+      # Image position will have: width, height, x, y
       def initialize(attrs = {})
-        if diff_file = attrs[:diff_file]
-          attrs[:diff_refs] = diff_file.diff_refs
-          attrs[:old_path] = diff_file.old_path
-          attrs[:new_path] = diff_file.new_path
-        end
-
-        if diff_refs = attrs[:diff_refs]
-          attrs[:base_sha]  = diff_refs.base_sha
-          attrs[:start_sha] = diff_refs.start_sha
-          attrs[:head_sha]  = diff_refs.head_sha
-        end
-
-        @old_path = attrs[:old_path]
-        @new_path = attrs[:new_path]
-        @base_sha  = attrs[:base_sha]
-        @start_sha = attrs[:start_sha]
-        @head_sha  = attrs[:head_sha]
-
-        @old_line = attrs[:old_line]
-        @new_line = attrs[:new_line]
+        @formatter = get_formatter_class(attrs[:position_type]).new(attrs)
       end
 
       # `Gitlab::Diff::Position` objects are stored as serialized attributes in
@@ -46,7 +34,11 @@ module Gitlab
       end
 
       def encode_with(coder)
-        coder['attributes'] = self.to_h
+        coder['attributes'] = formatter.to_h
+      end
+
+      def key
+        formatter.key
       end
 
       def ==(other)
@@ -54,20 +46,11 @@ module Gitlab
           other.diff_refs == diff_refs &&
           other.old_path == old_path &&
           other.new_path == new_path &&
-          other.old_line == old_line &&
-          other.new_line == new_line
+          other.formatter == formatter
       end
 
       def to_h
-        {
-          old_path: old_path,
-          new_path: new_path,
-          old_line: old_line,
-          new_line: new_line,
-          base_sha:  base_sha,
-          start_sha: start_sha,
-          head_sha:  head_sha
-        }
+        formatter.to_h
       end
 
       def inspect
@@ -75,23 +58,15 @@ module Gitlab
       end
 
       def complete?
-        file_path.present? &&
-          (old_line || new_line) &&
-          diff_refs.complete?
+        file_path.present? && formatter.complete? && diff_refs.complete?
       end
 
       def to_json(opts = nil)
-        JSON.generate(self.to_h, opts)
+        JSON.generate(formatter.to_h, opts)
       end
 
       def type
-        if old_line && new_line
-          nil
-        elsif new_line
-          'new'
-        else
-          'old'
-        end
+        formatter.line_age
       end
 
       def unchanged?
@@ -150,6 +125,17 @@ module Gitlab
 
         diff_refs.compare_in(repository.project).diffs(paths: paths, expanded: true).diff_files.first
       end
+
+      def get_formatter_class(type)
+        type ||= "text"
+
+        case type
+        when 'image'
+          Gitlab::Diff::Formatters::ImageFormatter
+        else
+          Gitlab::Diff::Formatters::TextFormatter
+        end
+      end
     end
   end
 end
diff --git a/spec/factories/merge_requests.rb b/spec/factories/merge_requests.rb
index cbec716d6ea..2c732aaf4ed 100644
--- a/spec/factories/merge_requests.rb
+++ b/spec/factories/merge_requests.rb
@@ -22,6 +22,11 @@ FactoryGirl.define do
     trait :with_diffs do
     end
 
+    trait :with_image_diffs do
+      source_branch "add_images_and_changes"
+      target_branch "master"
+    end
+
     trait :without_diffs do
       source_branch "improve/awesome"
       target_branch "master"
diff --git a/spec/features/merge_requests/diffs_spec.rb b/spec/features/merge_requests/diffs_spec.rb
index e9068f722d5..f4ba660ca39 100644
--- a/spec/features/merge_requests/diffs_spec.rb
+++ b/spec/features/merge_requests/diffs_spec.rb
@@ -42,8 +42,12 @@ feature 'Diffs URL', js: true do
         visit "#{diffs_project_merge_request_path(project, merge_request)}#{fragment}"
       end
 
-      it 'shows expanded note' do
-        expect(page).to have_selector(fragment, visible: true)
+      it 'shows collapsed note' do
+        wait_for_requests
+
+        expect(page).to have_selector('.discussion-notes.collapsed') do |note_container|
+          expect(note_container).to have_selector(fragment, visible: false)
+        end
       end
     end
   end
diff --git a/spec/features/merge_requests/image_diff_notes.rb b/spec/features/merge_requests/image_diff_notes.rb
new file mode 100644
index 00000000000..e8ca8a98d70
--- /dev/null
+++ b/spec/features/merge_requests/image_diff_notes.rb
@@ -0,0 +1,196 @@
+require 'spec_helper'
+
+feature 'image diff notes', js: true do
+  include NoteInteractionHelpers
+
+  let(:user) { create(:user) }
+  let(:project) { create(:project, :public, :repository) }
+
+  before do
+    project.team << [user, :master]
+    sign_in user
+
+    page.driver.set_cookie('sidebar_collapsed', 'true')
+
+    # Stub helper to return any blob file as image from public app folder.
+    # This is necessary to run this specs since we don't display repo images in capybara.
+    allow_any_instance_of(DiffHelper).to receive(:diff_file_blob_raw_path).and_return('/apple-touch-icon.png')
+  end
+
+  context 'create commit diff notes' do
+    commit_id = '2f63565e7aac07bcdadb654e253078b727143ec4'
+
+    describe 'create a new diff note' do
+      before do
+        visit project_commit_path(project, commit_id)
+        create_image_diff_note
+      end
+
+      it 'shows indicator badge on image diff' do
+        indicator = find('.js-image-badge')
+
+        expect(indicator).to have_content('1')
+      end
+
+      it 'shows the avatar badge on the new note' do
+        badge = find('.image-diff-avatar-link .badge')
+
+        expect(badge).to have_content('1')
+      end
+
+      it 'allows collapsing/expanding the discussion notes' do
+        find('.js-diff-notes-toggle', :first).click
+
+        expect(page).not_to have_content('image diff test comment')
+
+        find('.js-diff-notes-toggle').click
+
+        expect(page).to have_content('image diff test comment')
+      end
+    end
+
+    describe 'render commit diff notes' do
+      let(:path) { "files/images/6049019_460s.jpg" }
+      let(:commit) { project.commit('2f63565e7aac07bcdadb654e253078b727143ec4') }
+
+      let(:note1_position) do
+        Gitlab::Diff::Position.new(
+          old_path: path,
+          new_path: path,
+          width: 100,
+          height: 100,
+          x: 10,
+          y: 10,
+          position_type: "image",
+          diff_refs: commit.diff_refs
+        )
+      end
+
+      let(:note2_position) do
+        Gitlab::Diff::Position.new(
+          old_path: path,
+          new_path: path,
+          width: 100,
+          height: 100,
+          x: 20,
+          y: 20,
+          position_type: "image",
+          diff_refs: commit.diff_refs
+        )
+      end
+
+      let!(:note1) { create(:diff_note_on_commit, commit_id: commit.id, project: project, position: note1_position, note: 'my note 1') }
+      let!(:note2) { create(:diff_note_on_commit, commit_id: commit.id, project: project, position: note2_position, note: 'my note 2') }
+
+      before do
+        visit project_commit_path(project, commit.id)
+        wait_for_requests
+      end
+
+      it 'render diff indicators within the image diff frame' do
+        expect(page).to have_css('.js-image-badge', count: 2)
+      end
+
+      it 'shows the diff notes' do
+        expect(page).to have_css('.diff-content .note', count: 2)
+      end
+
+      it 'shows the diff notes with correct avatar badge numbers' do
+        expect(page).to have_css('.image-diff-avatar-link', text: 1)
+        expect(page).to have_css('.image-diff-avatar-link', text: 2)
+      end
+    end
+  end
+
+  %w(inline parallel).each do |view|
+    context "#{view} view" do
+      let(:merge_request) { create(:merge_request_with_diffs, :with_image_diffs, source_project: project, author: user) }
+      let(:path)          { "files/images/ee_repo_logo.png" }
+
+      let(:position) do
+        Gitlab::Diff::Position.new(
+          old_path: path,
+          new_path: path,
+          width: 100,
+          height: 100,
+          x: 1,
+          y: 1,
+          position_type: "image",
+          diff_refs: merge_request.diff_refs
+        )
+      end
+
+      let!(:note) { create(:diff_note_on_merge_request, project: project, noteable: merge_request, position: position) }
+
+      describe 'creating a new diff note' do
+        before do
+          visit diffs_project_merge_request_path(project, merge_request, view: view)
+          create_image_diff_note
+        end
+
+        it 'shows indicator badge on image diff' do
+          indicator = find('.js-image-badge', match: :first)
+
+          expect(indicator).to have_content('1')
+        end
+
+        it 'shows the avatar badge on the new note' do
+          badge = find('.image-diff-avatar-link .badge', match: :first)
+
+          expect(badge).to have_content('1')
+        end
+
+        it 'allows expanding/collapsing the discussion notes' do
+          page.all('.js-diff-notes-toggle')[0].trigger('click')
+          page.all('.js-diff-notes-toggle')[1].trigger('click')
+
+          expect(page).not_to have_content('image diff test comment')
+
+          page.all('.js-diff-notes-toggle')[0].trigger('click')
+          page.all('.js-diff-notes-toggle')[1].trigger('click')
+
+          expect(page).to have_content('image diff test comment')
+        end
+      end
+    end
+  end
+
+  describe 'discussion tab polling', :js do
+    let(:merge_request) { create(:merge_request_with_diffs, :with_image_diffs, source_project: project, author: user) }
+    let(:path)          { "files/images/ee_repo_logo.png" }
+
+    let(:position) do
+      Gitlab::Diff::Position.new(
+        old_path: path,
+        new_path: path,
+        width: 100,
+        height: 100,
+        x: 50,
+        y: 50,
+        position_type: "image",
+        diff_refs: merge_request.diff_refs
+      )
+    end
+
+    before do
+      visit project_merge_request_path(project, merge_request)
+    end
+
+    it 'render diff indicators within the image frame' do
+      diff_note = create(:diff_note_on_merge_request, project: project, noteable: merge_request, position: position)
+
+      wait_for_requests
+
+      expect(page).to have_selector('.image-comment-badge')
+      expect(page).to have_content(diff_note.note)
+    end
+  end
+end
+
+def create_image_diff_note
+  find('.js-add-image-diff-note-button', match: :first).click
+  page.all('.js-add-image-diff-note-button')[0].trigger('click')
+  find('.diff-content .note-textarea').native.send_keys('image diff test comment')
+  click_button 'Comment'
+  wait_for_requests
+end
diff --git a/spec/features/merge_requests/user_posts_diff_notes_spec.rb b/spec/features/merge_requests/user_posts_diff_notes_spec.rb
index e1ca4fe186c..7a773fb2baa 100644
--- a/spec/features/merge_requests/user_posts_diff_notes_spec.rb
+++ b/spec/features/merge_requests/user_posts_diff_notes_spec.rb
@@ -227,6 +227,7 @@ feature 'Merge requests > User posts diff notes', :js do
     write_comment_on_line(line_holder, diff_side)
 
     click_button 'Comment'
+
     wait_for_requests
 
     assert_comment_persistence(line_holder, asset_form_reset: asset_form_reset)
diff --git a/spec/javascripts/image_diff/helpers/badge_helper_spec.js b/spec/javascripts/image_diff/helpers/badge_helper_spec.js
new file mode 100644
index 00000000000..fb9c7e59031
--- /dev/null
+++ b/spec/javascripts/image_diff/helpers/badge_helper_spec.js
@@ -0,0 +1,132 @@
+import * as badgeHelper from '~/image_diff/helpers/badge_helper';
+import * as mockData from '../mock_data';
+
+describe('badge helper', () => {
+  const { coordinate, noteId, badgeText, badgeNumber } = mockData;
+  let containerEl;
+  let buttonEl;
+
+  beforeEach(() => {
+    containerEl = document.createElement('div');
+  });
+
+  describe('createImageBadge', () => {
+    beforeEach(() => {
+      buttonEl = badgeHelper.createImageBadge(noteId, coordinate);
+    });
+
+    it('should create button', () => {
+      expect(buttonEl.tagName).toEqual('BUTTON');
+      expect(buttonEl.getAttribute('type')).toEqual('button');
+    });
+
+    it('should set disabled attribute', () => {
+      expect(buttonEl.hasAttribute('disabled')).toEqual(true);
+    });
+
+    it('should set noteId', () => {
+      expect(buttonEl.dataset.noteId).toEqual(noteId);
+    });
+
+    it('should set coordinate', () => {
+      expect(buttonEl.style.left).toEqual(`${coordinate.x}px`);
+      expect(buttonEl.style.top).toEqual(`${coordinate.y}px`);
+    });
+
+    describe('classNames', () => {
+      it('should set .js-image-badge by default', () => {
+        expect(buttonEl.className).toEqual('js-image-badge');
+      });
+
+      it('should add additional class names if parameter is passed', () => {
+        const classNames = ['first-class', 'second-class'];
+        buttonEl = badgeHelper.createImageBadge(noteId, coordinate, classNames);
+
+        expect(buttonEl.className).toEqual(classNames.concat('js-image-badge').join(' '));
+      });
+    });
+  });
+
+  describe('addImageBadge', () => {
+    beforeEach(() => {
+      badgeHelper.addImageBadge(containerEl, {
+        coordinate,
+        badgeText,
+        noteId,
+      });
+      buttonEl = containerEl.querySelector('button');
+    });
+
+    it('should appends button to container', () => {
+      expect(buttonEl).toBeDefined();
+    });
+
+    it('should set the badge text', () => {
+      expect(buttonEl.innerText).toEqual(badgeText);
+    });
+
+    it('should set the button coordinates', () => {
+      expect(buttonEl.style.left).toEqual(`${coordinate.x}px`);
+      expect(buttonEl.style.top).toEqual(`${coordinate.y}px`);
+    });
+
+    it('should set the button noteId', () => {
+      expect(buttonEl.dataset.noteId).toEqual(noteId);
+    });
+  });
+
+  describe('addImageCommentBadge', () => {
+    beforeEach(() => {
+      badgeHelper.addImageCommentBadge(containerEl, {
+        coordinate,
+        noteId,
+      });
+      buttonEl = containerEl.querySelector('button');
+    });
+
+    it('should append icon button to container', () => {
+      expect(buttonEl).toBeDefined();
+    });
+
+    it('should create icon comment button', () => {
+      const iconEl = buttonEl.querySelector('i');
+      expect(iconEl).toBeDefined();
+      expect(iconEl.classList.contains('fa')).toEqual(true);
+      expect(iconEl.classList.contains('fa-comment-o')).toEqual(true);
+    });
+
+    it('should have .image-comment-badge.inverted in button class', () => {
+      expect(buttonEl.classList.contains('image-comment-badge')).toEqual(true);
+      expect(buttonEl.classList.contains('inverted')).toEqual(true);
+    });
+  });
+
+  describe('addAvatarBadge', () => {
+    let avatarBadgeEl;
+
+    beforeEach(() => {
+      containerEl.innerHTML = `
+        <div id="${noteId}">
+          <div class="badge hidden">
+          </div>
+        </div>
+      `;
+
+      badgeHelper.addAvatarBadge(containerEl, {
+        detail: {
+          noteId,
+          badgeNumber,
+        },
+      });
+      avatarBadgeEl = containerEl.querySelector(`#${noteId} .badge`);
+    });
+
+    it('should update badge number', () => {
+      expect(avatarBadgeEl.innerText).toEqual(badgeNumber.toString());
+    });
+
+    it('should remove hidden class', () => {
+      expect(avatarBadgeEl.classList.contains('hidden')).toEqual(false);
+    });
+  });
+});
diff --git a/spec/javascripts/image_diff/helpers/comment_indicator_helper_spec.js b/spec/javascripts/image_diff/helpers/comment_indicator_helper_spec.js
new file mode 100644
index 00000000000..a284b981d2a
--- /dev/null
+++ b/spec/javascripts/image_diff/helpers/comment_indicator_helper_spec.js
@@ -0,0 +1,139 @@
+import * as commentIndicatorHelper from '~/image_diff/helpers/comment_indicator_helper';
+import * as mockData from '../mock_data';
+
+describe('commentIndicatorHelper', () => {
+  const { coordinate } = mockData;
+  let containerEl;
+
+  beforeEach(() => {
+    containerEl = document.createElement('div');
+  });
+
+  describe('addCommentIndicator', () => {
+    let buttonEl;
+
+    beforeEach(() => {
+      commentIndicatorHelper.addCommentIndicator(containerEl, coordinate);
+      buttonEl = containerEl.querySelector('button');
+    });
+
+    it('should append button to container', () => {
+      expect(buttonEl).toBeDefined();
+    });
+
+    describe('button', () => {
+      it('should set coordinate', () => {
+        expect(buttonEl.style.left).toEqual(`${coordinate.x}px`);
+        expect(buttonEl.style.top).toEqual(`${coordinate.y}px`);
+      });
+
+      it('should contain image-comment-dark svg', () => {
+        const svgEl = buttonEl.querySelector('svg');
+        expect(svgEl).toBeDefined();
+
+        const svgLink = svgEl.querySelector('use').getAttribute('xlink:href');
+        expect(svgLink.indexOf('image-comment-dark') !== -1).toEqual(true);
+      });
+    });
+  });
+
+  describe('removeCommentIndicator', () => {
+    it('should return removed false if there is no comment-indicator', () => {
+      const result = commentIndicatorHelper.removeCommentIndicator(containerEl);
+      expect(result.removed).toEqual(false);
+    });
+
+    describe('has comment indicator', () => {
+      let result;
+
+      beforeEach(() => {
+        containerEl.innerHTML = `
+          <div class="comment-indicator" style="left:${coordinate.x}px; top: ${coordinate.y}px;">
+            <img src="${gl.TEST_HOST}/image.png">
+          </div>
+        `;
+        result = commentIndicatorHelper.removeCommentIndicator(containerEl);
+      });
+
+      it('should remove comment indicator', () => {
+        expect(containerEl.querySelector('.comment-indicator')).toBeNull();
+      });
+
+      it('should return removed true', () => {
+        expect(result.removed).toEqual(true);
+      });
+
+      it('should return indicator meta', () => {
+        expect(result.x).toEqual(coordinate.x);
+        expect(result.y).toEqual(coordinate.y);
+        expect(result.image).toBeDefined();
+        expect(result.image.width).toBeDefined();
+        expect(result.image.height).toBeDefined();
+      });
+    });
+  });
+
+  describe('showCommentIndicator', () => {
+    describe('commentIndicator exists', () => {
+      beforeEach(() => {
+        containerEl.innerHTML = `
+          <button class="comment-indicator"></button>
+        `;
+        commentIndicatorHelper.showCommentIndicator(containerEl, coordinate);
+      });
+
+      it('should set commentIndicator coordinates', () => {
+        const commentIndicatorEl = containerEl.querySelector('.comment-indicator');
+        expect(commentIndicatorEl.style.left).toEqual(`${coordinate.x}px`);
+        expect(commentIndicatorEl.style.top).toEqual(`${coordinate.y}px`);
+      });
+    });
+
+    describe('commentIndicator does not exist', () => {
+      beforeEach(() => {
+        commentIndicatorHelper.showCommentIndicator(containerEl, coordinate);
+      });
+
+      it('should addCommentIndicator', () => {
+        const buttonEl = containerEl.querySelector('.comment-indicator');
+        expect(buttonEl).toBeDefined();
+        expect(buttonEl.style.left).toEqual(`${coordinate.x}px`);
+        expect(buttonEl.style.top).toEqual(`${coordinate.y}px`);
+      });
+    });
+  });
+
+  describe('commentIndicatorOnClick', () => {
+    let event;
+    let textAreaEl;
+
+    beforeEach(() => {
+      containerEl.innerHTML = `
+        <div class="diff-viewer">
+          <button></button>
+          <div class="note-container">
+            <textarea class="note-textarea"></textarea>
+          </div>
+        </div>
+      `;
+      textAreaEl = containerEl.querySelector('textarea');
+
+      event = {
+        stopPropagation: () => {},
+        currentTarget: containerEl.querySelector('button'),
+      };
+
+      spyOn(event, 'stopPropagation');
+      spyOn(textAreaEl, 'focus');
+      commentIndicatorHelper.commentIndicatorOnClick(event);
+    });
+
+    it('should stopPropagation', () => {
+      expect(event.stopPropagation).toHaveBeenCalled();
+    });
+
+    it('should focus textAreaEl', () => {
+      expect(textAreaEl.focus).toHaveBeenCalled();
+    });
+  });
+});
diff --git a/spec/javascripts/image_diff/helpers/dom_helper_spec.js b/spec/javascripts/image_diff/helpers/dom_helper_spec.js
new file mode 100644
index 00000000000..8dde924e8ae
--- /dev/null
+++ b/spec/javascripts/image_diff/helpers/dom_helper_spec.js
@@ -0,0 +1,118 @@
+import * as domHelper from '~/image_diff/helpers/dom_helper';
+import * as mockData from '../mock_data';
+
+describe('domHelper', () => {
+  const { imageMeta, badgeNumber } = mockData;
+
+  describe('setPositionDataAttribute', () => {
+    let containerEl;
+    let attributeAfterCall;
+    const position = {
+      myProperty: 'myProperty',
+    };
+
+    beforeEach(() => {
+      containerEl = document.createElement('div');
+      containerEl.dataset.position = JSON.stringify(position);
+      domHelper.setPositionDataAttribute(containerEl, imageMeta);
+      attributeAfterCall = JSON.parse(containerEl.dataset.position);
+    });
+
+    it('should set x, y, width, height', () => {
+      expect(attributeAfterCall.x).toEqual(imageMeta.x);
+      expect(attributeAfterCall.y).toEqual(imageMeta.y);
+      expect(attributeAfterCall.width).toEqual(imageMeta.width);
+      expect(attributeAfterCall.height).toEqual(imageMeta.height);
+    });
+
+    it('should not override other properties', () => {
+      expect(attributeAfterCall.myProperty).toEqual('myProperty');
+    });
+  });
+
+  describe('updateDiscussionAvatarBadgeNumber', () => {
+    let discussionEl;
+
+    beforeEach(() => {
+      discussionEl = document.createElement('div');
+      discussionEl.innerHTML = `
+        <a href="#" class="image-diff-avatar-link">
+          <div class="badge"></div>
+        </a>
+      `;
+      domHelper.updateDiscussionAvatarBadgeNumber(discussionEl, badgeNumber);
+    });
+
+    it('should update avatar badge number', () => {
+      expect(discussionEl.querySelector('.badge').innerText).toEqual(badgeNumber.toString());
+    });
+  });
+
+  describe('updateDiscussionBadgeNumber', () => {
+    let discussionEl;
+
+    beforeEach(() => {
+      discussionEl = document.createElement('div');
+      discussionEl.innerHTML = `
+        <div class="badge"></div>
+      `;
+      domHelper.updateDiscussionBadgeNumber(discussionEl, badgeNumber);
+    });
+
+    it('should update discussion badge number', () => {
+      expect(discussionEl.querySelector('.badge').innerText).toEqual(badgeNumber.toString());
+    });
+  });
+
+  describe('toggleCollapsed', () => {
+    let element;
+    let discussionNotesEl;
+
+    beforeEach(() => {
+      element = document.createElement('div');
+      element.innerHTML = `
+        <div class="discussion-notes">
+          <button></button>
+          <form class="discussion-form"></form>
+        </div>
+      `;
+      discussionNotesEl = element.querySelector('.discussion-notes');
+    });
+
+    describe('not collapsed', () => {
+      beforeEach(() => {
+        domHelper.toggleCollapsed({
+          currentTarget: element.querySelector('button'),
+        });
+      });
+
+      it('should add collapsed class', () => {
+        expect(discussionNotesEl.classList.contains('collapsed')).toEqual(true);
+      });
+
+      it('should force formEl to display none', () => {
+        const formEl = element.querySelector('.discussion-form');
+        expect(formEl.style.display).toEqual('none');
+      });
+    });
+
+    describe('collapsed', () => {
+      beforeEach(() => {
+        discussionNotesEl.classList.add('collapsed');
+
+        domHelper.toggleCollapsed({
+          currentTarget: element.querySelector('button'),
+        });
+      });
+
+      it('should remove collapsed class', () => {
+        expect(discussionNotesEl.classList.contains('collapsed')).toEqual(false);
+      });
+
+      it('should force formEl to display block', () => {
+        const formEl = element.querySelector('.discussion-form');
+        expect(formEl.style.display).toEqual('block');
+      });
+    });
+  });
+});
diff --git a/spec/javascripts/image_diff/helpers/utils_helper_spec.js b/spec/javascripts/image_diff/helpers/utils_helper_spec.js
new file mode 100644
index 00000000000..56d77a05c4c
--- /dev/null
+++ b/spec/javascripts/image_diff/helpers/utils_helper_spec.js
@@ -0,0 +1,207 @@
+import * as utilsHelper from '~/image_diff/helpers/utils_helper';
+import ImageDiff from '~/image_diff/image_diff';
+import ReplacedImageDiff from '~/image_diff/replaced_image_diff';
+import ImageBadge from '~/image_diff/image_badge';
+import * as mockData from '../mock_data';
+
+describe('utilsHelper', () => {
+  const {
+    noteId,
+    discussionId,
+    image,
+    imageProperties,
+    imageMeta,
+  } = mockData;
+
+  describe('resizeCoordinatesToImageElement', () => {
+    let result;
+
+    beforeEach(() => {
+      result = utilsHelper.resizeCoordinatesToImageElement(image, imageMeta);
+    });
+
+    it('should return x based on widthRatio', () => {
+      expect(result.x).toEqual(imageMeta.x * 0.5);
+    });
+
+    it('should return y based on heightRatio', () => {
+      expect(result.y).toEqual(imageMeta.y * 0.5);
+    });
+
+    it('should return image width', () => {
+      expect(result.width).toEqual(image.width);
+    });
+
+    it('should return image height', () => {
+      expect(result.height).toEqual(image.height);
+    });
+  });
+
+  describe('generateBadgeFromDiscussionDOM', () => {
+    let discussionEl;
+    let result;
+
+    beforeEach(() => {
+      const imageFrameEl = document.createElement('div');
+      imageFrameEl.innerHTML = `
+        <img src="${gl.TEST_HOST}/image.png">
+      `;
+      discussionEl = document.createElement('div');
+      discussionEl.dataset.discussionId = discussionId;
+      discussionEl.innerHTML = `
+        <div class="note" id="${noteId}"></div>
+      `;
+      discussionEl.dataset.position = JSON.stringify(imageMeta);
+      result = utilsHelper.generateBadgeFromDiscussionDOM(imageFrameEl, discussionEl);
+    });
+
+    it('should return actual image properties', () => {
+      const { actual } = result;
+      expect(actual.x).toEqual(imageMeta.x);
+      expect(actual.y).toEqual(imageMeta.y);
+      expect(actual.width).toEqual(imageMeta.width);
+      expect(actual.height).toEqual(imageMeta.height);
+    });
+
+    it('should return browser image properties', () => {
+      const { browser } = result;
+      expect(browser.x).toBeDefined();
+      expect(browser.y).toBeDefined();
+      expect(browser.width).toBeDefined();
+      expect(browser.height).toBeDefined();
+    });
+
+    it('should return instance of ImageBadge', () => {
+      expect(result instanceof ImageBadge).toEqual(true);
+    });
+
+    it('should return noteId', () => {
+      expect(result.noteId).toEqual(noteId);
+    });
+
+    it('should return discussionId', () => {
+      expect(result.discussionId).toEqual(discussionId);
+    });
+  });
+
+  describe('getTargetSelection', () => {
+    let containerEl;
+
+    beforeEach(() => {
+      containerEl = {
+        querySelector: () => imageProperties,
+      };
+    });
+
+    function generateEvent(offsetX, offsetY) {
+      return {
+        currentTarget: containerEl,
+        offsetX,
+        offsetY,
+      };
+    }
+
+    it('should return browser properties', () => {
+      const event = generateEvent(25, 25);
+      const result = utilsHelper.getTargetSelection(event);
+
+      const { browser } = result;
+      expect(browser.x).toEqual(event.offsetX);
+      expect(browser.y).toEqual(event.offsetY);
+      expect(browser.width).toEqual(imageProperties.width);
+      expect(browser.height).toEqual(imageProperties.height);
+    });
+
+    it('should return resized actual image properties', () => {
+      const event = generateEvent(50, 50);
+      const result = utilsHelper.getTargetSelection(event);
+
+      const { actual } = result;
+      expect(actual.x).toEqual(100);
+      expect(actual.y).toEqual(100);
+      expect(actual.width).toEqual(imageProperties.naturalWidth);
+      expect(actual.height).toEqual(imageProperties.naturalHeight);
+    });
+
+    describe('normalize coordinates', () => {
+      it('should return x = 0 if x < 0', () => {
+        const event = generateEvent(-5, 50);
+        const result = utilsHelper.getTargetSelection(event);
+        expect(result.browser.x).toEqual(0);
+      });
+
+      it('should return x = width if x > width', () => {
+        const event = generateEvent(1000, 50);
+        const result = utilsHelper.getTargetSelection(event);
+        expect(result.browser.x).toEqual(imageProperties.width);
+      });
+
+      it('should return y = 0 if y < 0', () => {
+        const event = generateEvent(50, -10);
+        const result = utilsHelper.getTargetSelection(event);
+        expect(result.browser.y).toEqual(0);
+      });
+
+      it('should return y = height if y > height', () => {
+        const event = generateEvent(50, 1000);
+        const result = utilsHelper.getTargetSelection(event);
+        expect(result.browser.y).toEqual(imageProperties.height);
+      });
+    });
+  });
+
+  describe('initImageDiff', () => {
+    let glCache;
+    let fileEl;
+
+    beforeEach(() => {
+      window.gl = window.gl || (window.gl = {});
+      glCache = window.gl;
+      window.gl.ImageFile = () => {};
+      fileEl = document.createElement('div');
+      fileEl.innerHTML = `
+        <div class="diff-file"></div>
+      `;
+
+      spyOn(ImageDiff.prototype, 'init').and.callFake(() => {});
+      spyOn(ReplacedImageDiff.prototype, 'init').and.callFake(() => {});
+    });
+
+    afterEach(() => {
+      window.gl = glCache;
+    });
+
+    it('should initialize gl.ImageFile', () => {
+      spyOn(window.gl, 'ImageFile');
+
+      utilsHelper.initImageDiff(fileEl, false, false);
+      expect(gl.ImageFile).toHaveBeenCalled();
+    });
+
+    it('should initialize ImageDiff if js-single-image', () => {
+      const diffFileEl = fileEl.querySelector('.diff-file');
+      diffFileEl.innerHTML = `
+        <div class="js-single-image">
+        </div>
+      `;
+
+      const imageDiff = utilsHelper.initImageDiff(fileEl, true, false);
+      expect(ImageDiff.prototype.init).toHaveBeenCalled();
+      expect(imageDiff.canCreateNote).toEqual(true);
+      expect(imageDiff.renderCommentBadge).toEqual(false);
+    });
+
+    it('should initialize ReplacedImageDiff if js-replaced-image', () => {
+      const diffFileEl = fileEl.querySelector('.diff-file');
+      diffFileEl.innerHTML = `
+        <div class="js-replaced-image">
+        </div>
+      `;
+
+      const replacedImageDiff = utilsHelper.initImageDiff(fileEl, false, true);
+      expect(ReplacedImageDiff.prototype.init).toHaveBeenCalled();
+      expect(replacedImageDiff.canCreateNote).toEqual(false);
+      expect(replacedImageDiff.renderCommentBadge).toEqual(true);
+    });
+  });
+});
diff --git a/spec/javascripts/image_diff/image_badge_spec.js b/spec/javascripts/image_diff/image_badge_spec.js
new file mode 100644
index 00000000000..87f98fc0926
--- /dev/null
+++ b/spec/javascripts/image_diff/image_badge_spec.js
@@ -0,0 +1,84 @@
+import ImageBadge from '~/image_diff/image_badge';
+import imageDiffHelper from '~/image_diff/helpers/index';
+import * as mockData from './mock_data';
+
+describe('ImageBadge', () => {
+  const { noteId, discussionId, imageMeta } = mockData;
+  const options = {
+    noteId,
+    discussionId,
+  };
+
+  it('should save actual property', () => {
+    const imageBadge = new ImageBadge(Object.assign({}, options, {
+      actual: imageMeta,
+    }));
+
+    const { actual } = imageBadge;
+    expect(actual.x).toEqual(imageMeta.x);
+    expect(actual.y).toEqual(imageMeta.y);
+    expect(actual.width).toEqual(imageMeta.width);
+    expect(actual.height).toEqual(imageMeta.height);
+  });
+
+  it('should save browser property', () => {
+    const imageBadge = new ImageBadge(Object.assign({}, options, {
+      browser: imageMeta,
+    }));
+
+    const { browser } = imageBadge;
+    expect(browser.x).toEqual(imageMeta.x);
+    expect(browser.y).toEqual(imageMeta.y);
+    expect(browser.width).toEqual(imageMeta.width);
+    expect(browser.height).toEqual(imageMeta.height);
+  });
+
+  it('should save noteId', () => {
+    const imageBadge = new ImageBadge(options);
+    expect(imageBadge.noteId).toEqual(noteId);
+  });
+
+  it('should save discussionId', () => {
+    const imageBadge = new ImageBadge(options);
+    expect(imageBadge.discussionId).toEqual(discussionId);
+  });
+
+  describe('default values', () => {
+    let imageBadge;
+
+    beforeEach(() => {
+      imageBadge = new ImageBadge(options);
+    });
+
+    it('should return defaultimageMeta if actual property is not provided', () => {
+      const { actual } = imageBadge;
+      expect(actual.x).toEqual(0);
+      expect(actual.y).toEqual(0);
+      expect(actual.width).toEqual(0);
+      expect(actual.height).toEqual(0);
+    });
+
+    it('should return defaultimageMeta if browser property is not provided', () => {
+      const { browser } = imageBadge;
+      expect(browser.x).toEqual(0);
+      expect(browser.y).toEqual(0);
+      expect(browser.width).toEqual(0);
+      expect(browser.height).toEqual(0);
+    });
+  });
+
+  describe('imageEl property is provided and not browser property', () => {
+    beforeEach(() => {
+      spyOn(imageDiffHelper, 'resizeCoordinatesToImageElement').and.returnValue(true);
+    });
+
+    it('should generate browser property', () => {
+      const imageBadge = new ImageBadge(Object.assign({}, options, {
+        imageEl: document.createElement('img'),
+      }));
+
+      expect(imageDiffHelper.resizeCoordinatesToImageElement).toHaveBeenCalled();
+      expect(imageBadge.browser).toEqual(true);
+    });
+  });
+});
diff --git a/spec/javascripts/image_diff/image_diff_spec.js b/spec/javascripts/image_diff/image_diff_spec.js
new file mode 100644
index 00000000000..346282328c7
--- /dev/null
+++ b/spec/javascripts/image_diff/image_diff_spec.js
@@ -0,0 +1,361 @@
+import ImageDiff from '~/image_diff/image_diff';
+import * as imageUtility from '~/lib/utils/image_utility';
+import imageDiffHelper from '~/image_diff/helpers/index';
+import * as mockData from './mock_data';
+
+describe('ImageDiff', () => {
+  let element;
+  let imageDiff;
+
+  beforeEach(() => {
+    setFixtures(`
+      <div id="element">
+        <div class="diff-file">
+          <div class="js-image-frame">
+            <img src="${gl.TEST_HOST}/image.png">
+            <div class="comment-indicator"></div>
+            <div id="badge-1" class="badge">1</div>
+            <div id="badge-2" class="badge">2</div>
+            <div id="badge-3" class="badge">3</div>
+          </div>
+          <div class="note-container">
+            <div class="discussion-notes">
+              <div class="js-diff-notes-toggle"></div>
+              <div class="notes"></div>
+            </div>
+            <div class="discussion-notes">
+              <div class="js-diff-notes-toggle"></div>
+              <div class="notes"></div>
+            </div>
+          </div>
+        </div>
+      </div>
+    `);
+    element = document.getElementById('element');
+  });
+
+  describe('constructor', () => {
+    beforeEach(() => {
+      imageDiff = new ImageDiff(element, {
+        canCreateNote: true,
+        renderCommentBadge: true,
+      });
+    });
+
+    it('should set el', () => {
+      expect(imageDiff.el).toEqual(element);
+    });
+
+    it('should set canCreateNote', () => {
+      expect(imageDiff.canCreateNote).toEqual(true);
+    });
+
+    it('should set renderCommentBadge', () => {
+      expect(imageDiff.renderCommentBadge).toEqual(true);
+    });
+
+    it('should set $noteContainer', () => {
+      expect(imageDiff.$noteContainer[0]).toEqual(element.querySelector('.note-container'));
+    });
+
+    describe('default', () => {
+      beforeEach(() => {
+        imageDiff = new ImageDiff(element);
+      });
+
+      it('should set canCreateNote as false', () => {
+        expect(imageDiff.canCreateNote).toEqual(false);
+      });
+
+      it('should set renderCommentBadge as false', () => {
+        expect(imageDiff.renderCommentBadge).toEqual(false);
+      });
+    });
+  });
+
+  describe('init', () => {
+    beforeEach(() => {
+      spyOn(ImageDiff.prototype, 'bindEvents').and.callFake(() => {});
+      imageDiff = new ImageDiff(element);
+      imageDiff.init();
+    });
+
+    it('should set imageFrameEl', () => {
+      expect(imageDiff.imageFrameEl).toEqual(element.querySelector('.diff-file .js-image-frame'));
+    });
+
+    it('should set imageEl', () => {
+      expect(imageDiff.imageEl).toEqual(element.querySelector('.diff-file .js-image-frame img'));
+    });
+
+    it('should call bindEvents', () => {
+      expect(imageDiff.bindEvents).toHaveBeenCalled();
+    });
+  });
+
+  describe('bindEvents', () => {
+    let imageEl;
+
+    beforeEach(() => {
+      spyOn(imageDiffHelper, 'toggleCollapsed').and.callFake(() => {});
+      spyOn(imageDiffHelper, 'commentIndicatorOnClick').and.callFake(() => {});
+      spyOn(imageDiffHelper, 'removeCommentIndicator').and.callFake(() => {});
+      spyOn(ImageDiff.prototype, 'imageClicked').and.callFake(() => {});
+      spyOn(ImageDiff.prototype, 'addBadge').and.callFake(() => {});
+      spyOn(ImageDiff.prototype, 'removeBadge').and.callFake(() => {});
+      spyOn(ImageDiff.prototype, 'renderBadges').and.callFake(() => {});
+      imageEl = element.querySelector('.diff-file .js-image-frame img');
+    });
+
+    describe('default', () => {
+      beforeEach(() => {
+        spyOn(imageUtility, 'isImageLoaded').and.returnValue(false);
+        imageDiff = new ImageDiff(element);
+        imageDiff.imageEl = imageEl;
+        imageDiff.bindEvents();
+      });
+
+      it('should register click event delegation to js-diff-notes-toggle', () => {
+        element.querySelector('.js-diff-notes-toggle').click();
+        expect(imageDiffHelper.toggleCollapsed).toHaveBeenCalled();
+      });
+
+      it('should register click event delegation to comment-indicator', () => {
+        element.querySelector('.comment-indicator').click();
+        expect(imageDiffHelper.commentIndicatorOnClick).toHaveBeenCalled();
+      });
+    });
+
+    describe('image loaded', () => {
+      beforeEach(() => {
+        spyOn(imageUtility, 'isImageLoaded').and.returnValue(true);
+        imageDiff = new ImageDiff(element);
+        imageDiff.imageEl = imageEl;
+      });
+
+      it('should renderBadges', () => {});
+    });
+
+    describe('image not loaded', () => {
+      beforeEach(() => {
+        spyOn(imageUtility, 'isImageLoaded').and.returnValue(false);
+        imageDiff = new ImageDiff(element);
+        imageDiff.imageEl = imageEl;
+        imageDiff.bindEvents();
+      });
+
+      it('should registers load eventListener', () => {
+        const loadEvent = new Event('load');
+        imageEl.dispatchEvent(loadEvent);
+        expect(imageDiff.renderBadges).toHaveBeenCalled();
+      });
+    });
+
+    describe('canCreateNote', () => {
+      beforeEach(() => {
+        spyOn(imageUtility, 'isImageLoaded').and.returnValue(false);
+        imageDiff = new ImageDiff(element, {
+          canCreateNote: true,
+        });
+        imageDiff.imageEl = imageEl;
+        imageDiff.bindEvents();
+      });
+
+      it('should register click.imageDiff event', () => {
+        const event = new CustomEvent('click.imageDiff');
+        element.dispatchEvent(event);
+        expect(imageDiff.imageClicked).toHaveBeenCalled();
+      });
+
+      it('should register blur.imageDiff event', () => {
+        const event = new CustomEvent('blur.imageDiff');
+        element.dispatchEvent(event);
+        expect(imageDiffHelper.removeCommentIndicator).toHaveBeenCalled();
+      });
+
+      it('should register addBadge.imageDiff event', () => {
+        const event = new CustomEvent('addBadge.imageDiff');
+        element.dispatchEvent(event);
+        expect(imageDiff.addBadge).toHaveBeenCalled();
+      });
+
+      it('should register removeBadge.imageDiff event', () => {
+        const event = new CustomEvent('removeBadge.imageDiff');
+        element.dispatchEvent(event);
+        expect(imageDiff.removeBadge).toHaveBeenCalled();
+      });
+    });
+
+    describe('canCreateNote is false', () => {
+      beforeEach(() => {
+        spyOn(imageUtility, 'isImageLoaded').and.returnValue(false);
+        imageDiff = new ImageDiff(element);
+        imageDiff.imageEl = imageEl;
+        imageDiff.bindEvents();
+      });
+
+      it('should not register click.imageDiff event', () => {
+        const event = new CustomEvent('click.imageDiff');
+        element.dispatchEvent(event);
+        expect(imageDiff.imageClicked).not.toHaveBeenCalled();
+      });
+    });
+  });
+
+  describe('imageClicked', () => {
+    beforeEach(() => {
+      spyOn(imageDiffHelper, 'getTargetSelection').and.returnValue({
+        actual: {},
+        browser: {},
+      });
+      spyOn(imageDiffHelper, 'setPositionDataAttribute').and.callFake(() => {});
+      spyOn(imageDiffHelper, 'showCommentIndicator').and.callFake(() => {});
+      imageDiff = new ImageDiff(element);
+      imageDiff.imageClicked({
+        detail: {
+          currentTarget: {},
+        },
+      });
+    });
+
+    it('should call getTargetSelection', () => {
+      expect(imageDiffHelper.getTargetSelection).toHaveBeenCalled();
+    });
+
+    it('should call setPositionDataAttribute', () => {
+      expect(imageDiffHelper.setPositionDataAttribute).toHaveBeenCalled();
+    });
+
+    it('should call showCommentIndicator', () => {
+      expect(imageDiffHelper.showCommentIndicator).toHaveBeenCalled();
+    });
+  });
+
+  describe('renderBadges', () => {
+    beforeEach(() => {
+      spyOn(ImageDiff.prototype, 'renderBadge').and.callFake(() => {});
+      imageDiff = new ImageDiff(element);
+      imageDiff.renderBadges();
+    });
+
+    it('should call renderBadge for each discussionEl', () => {
+      const discussionEls = element.querySelectorAll('.note-container .discussion-notes .notes');
+      expect(imageDiff.renderBadge.calls.count()).toEqual(discussionEls.length);
+    });
+  });
+
+  describe('renderBadge', () => {
+    let discussionEls;
+
+    beforeEach(() => {
+      spyOn(imageDiffHelper, 'addImageBadge').and.callFake(() => {});
+      spyOn(imageDiffHelper, 'addImageCommentBadge').and.callFake(() => {});
+      spyOn(imageDiffHelper, 'generateBadgeFromDiscussionDOM').and.returnValue({
+        browser: {},
+        noteId: 'noteId',
+      });
+      discussionEls = element.querySelectorAll('.note-container .discussion-notes .notes');
+      imageDiff = new ImageDiff(element);
+      imageDiff.renderBadge(discussionEls[0], 0);
+    });
+
+    it('should populate imageBadges', () => {
+      expect(imageDiff.imageBadges.length).toEqual(1);
+    });
+
+    describe('renderCommentBadge', () => {
+      beforeEach(() => {
+        imageDiff.renderCommentBadge = true;
+        imageDiff.renderBadge(discussionEls[0], 0);
+      });
+
+      it('should call addImageCommentBadge', () => {
+        expect(imageDiffHelper.addImageCommentBadge).toHaveBeenCalled();
+      });
+    });
+
+    describe('renderCommentBadge is false', () => {
+      it('should call addImageBadge', () => {
+        expect(imageDiffHelper.addImageBadge).toHaveBeenCalled();
+      });
+    });
+  });
+
+  describe('addBadge', () => {
+    beforeEach(() => {
+      spyOn(imageDiffHelper, 'addImageBadge').and.callFake(() => {});
+      spyOn(imageDiffHelper, 'addAvatarBadge').and.callFake(() => {});
+      spyOn(imageDiffHelper, 'updateDiscussionBadgeNumber').and.callFake(() => {});
+      imageDiff = new ImageDiff(element);
+      imageDiff.imageFrameEl = element.querySelector('.diff-file .js-image-frame');
+      imageDiff.addBadge({
+        detail: {
+          x: 0,
+          y: 1,
+          width: 25,
+          height: 50,
+          noteId: 'noteId',
+          discussionId: 'discussionId',
+        },
+      });
+    });
+
+    it('should add imageBadge to imageBadges', () => {
+      expect(imageDiff.imageBadges.length).toEqual(1);
+    });
+
+    it('should call addImageBadge', () => {
+      expect(imageDiffHelper.addImageBadge).toHaveBeenCalled();
+    });
+
+    it('should call addAvatarBadge', () => {
+      expect(imageDiffHelper.addAvatarBadge).toHaveBeenCalled();
+    });
+
+    it('should call updateDiscussionBadgeNumber', () => {
+      expect(imageDiffHelper.updateDiscussionBadgeNumber).toHaveBeenCalled();
+    });
+  });
+
+  describe('removeBadge', () => {
+    beforeEach(() => {
+      const { imageMeta } = mockData;
+
+      spyOn(imageDiffHelper, 'updateDiscussionBadgeNumber').and.callFake(() => {});
+      spyOn(imageDiffHelper, 'updateDiscussionAvatarBadgeNumber').and.callFake(() => {});
+      imageDiff = new ImageDiff(element);
+      imageDiff.imageBadges = [imageMeta, imageMeta, imageMeta];
+      imageDiff.imageFrameEl = element.querySelector('.diff-file .js-image-frame');
+      imageDiff.removeBadge({
+        detail: {
+          badgeNumber: 2,
+        },
+      });
+    });
+
+    describe('cascade badge count', () => {
+      it('should update next imageBadgeEl value', () => {
+        const imageBadgeEls = imageDiff.imageFrameEl.querySelectorAll('.badge');
+        expect(imageBadgeEls[0].innerText).toEqual('1');
+        expect(imageBadgeEls[1].innerText).toEqual('2');
+        expect(imageBadgeEls.length).toEqual(2);
+      });
+
+      it('should call updateDiscussionBadgeNumber', () => {
+        expect(imageDiffHelper.updateDiscussionBadgeNumber).toHaveBeenCalled();
+      });
+
+      it('should call updateDiscussionAvatarBadgeNumber', () => {
+        expect(imageDiffHelper.updateDiscussionAvatarBadgeNumber).toHaveBeenCalled();
+      });
+    });
+
+    it('should remove badge from imageBadges', () => {
+      expect(imageDiff.imageBadges.length).toEqual(2);
+    });
+
+    it('should remove imageBadgeEl', () => {
+      expect(imageDiff.imageFrameEl.querySelector('#badge-2')).toBeNull();
+    });
+  });
+});
diff --git a/spec/javascripts/image_diff/init_discussion_tab_spec.js b/spec/javascripts/image_diff/init_discussion_tab_spec.js
new file mode 100644
index 00000000000..7c447d6f70d
--- /dev/null
+++ b/spec/javascripts/image_diff/init_discussion_tab_spec.js
@@ -0,0 +1,37 @@
+import initDiscussionTab from '~/image_diff/init_discussion_tab';
+import imageDiffHelper from '~/image_diff/helpers/index';
+
+describe('initDiscussionTab', () => {
+  beforeEach(() => {
+    setFixtures(`
+      <div class="timeline-content">
+        <div class="diff-file js-image-file"></div>
+        <div class="diff-file js-image-file"></div>
+      </div>
+    `);
+  });
+
+  it('should pass canCreateNote as false to initImageDiff', (done) => {
+    spyOn(imageDiffHelper, 'initImageDiff').and.callFake((diffFileEl, canCreateNote) => {
+      expect(canCreateNote).toEqual(false);
+      done();
+    });
+
+    initDiscussionTab();
+  });
+
+  it('should pass renderCommentBadge as true to initImageDiff', (done) => {
+    spyOn(imageDiffHelper, 'initImageDiff').and.callFake((diffFileEl, canCreateNote, renderCommentBadge) => {
+      expect(renderCommentBadge).toEqual(true);
+      done();
+    });
+
+    initDiscussionTab();
+  });
+
+  it('should call initImageDiff for each diffFileEls', () => {
+    spyOn(imageDiffHelper, 'initImageDiff').and.callFake(() => {});
+    initDiscussionTab();
+    expect(imageDiffHelper.initImageDiff.calls.count()).toEqual(2);
+  });
+});
diff --git a/spec/javascripts/image_diff/mock_data.js b/spec/javascripts/image_diff/mock_data.js
new file mode 100644
index 00000000000..a0d1732dd0a
--- /dev/null
+++ b/spec/javascripts/image_diff/mock_data.js
@@ -0,0 +1,28 @@
+export const noteId = 'noteId';
+export const discussionId = 'discussionId';
+export const badgeText = 'badgeText';
+export const badgeNumber = 5;
+
+export const coordinate = {
+  x: 100,
+  y: 100,
+};
+
+export const image = {
+  width: 100,
+  height: 100,
+};
+
+export const imageProperties = {
+  width: image.width,
+  height: image.height,
+  naturalWidth: image.width * 2,
+  naturalHeight: image.height * 2,
+};
+
+export const imageMeta = {
+  x: coordinate.x,
+  y: coordinate.y,
+  width: imageProperties.naturalWidth,
+  height: imageProperties.naturalHeight,
+};
diff --git a/spec/javascripts/image_diff/replaced_image_diff_spec.js b/spec/javascripts/image_diff/replaced_image_diff_spec.js
new file mode 100644
index 00000000000..5f8cd7c531a
--- /dev/null
+++ b/spec/javascripts/image_diff/replaced_image_diff_spec.js
@@ -0,0 +1,312 @@
+import ReplacedImageDiff from '~/image_diff/replaced_image_diff';
+import ImageDiff from '~/image_diff/image_diff';
+import { viewTypes } from '~/image_diff/view_types';
+import imageDiffHelper from '~/image_diff/helpers/index';
+
+describe('ReplacedImageDiff', () => {
+  let element;
+  let replacedImageDiff;
+
+  beforeEach(() => {
+    setFixtures(`
+      <div id="element">
+        <div class="two-up">
+          <div class="js-image-frame">
+            <img src="${gl.TEST_HOST}/image.png">
+          </div>
+        </div>
+        <div class="swipe">
+          <div class="js-image-frame">
+            <img src="${gl.TEST_HOST}/image.png">
+          </div>
+        </div>
+        <div class="onion-skin">
+          <div class="js-image-frame">
+            <img src="${gl.TEST_HOST}/image.png">
+          </div>
+        </div>
+        <div class="view-modes-menu">
+          <div class="two-up">2-up</div>
+          <div class="swipe">Swipe</div>
+          <div class="onion-skin">Onion skin</div>
+        </div>
+      </div>
+    `);
+    element = document.getElementById('element');
+  });
+
+  function setupImageFrameEls() {
+    replacedImageDiff.imageFrameEls = [];
+    replacedImageDiff.imageFrameEls[viewTypes.TWO_UP] = element.querySelector('.two-up .js-image-frame');
+    replacedImageDiff.imageFrameEls[viewTypes.SWIPE] = element.querySelector('.swipe .js-image-frame');
+    replacedImageDiff.imageFrameEls[viewTypes.ONION_SKIN] = element.querySelector('.onion-skin .js-image-frame');
+  }
+
+  function setupViewModesEls() {
+    replacedImageDiff.viewModesEls = [];
+    replacedImageDiff.viewModesEls[viewTypes.TWO_UP] = element.querySelector('.view-modes-menu .two-up');
+    replacedImageDiff.viewModesEls[viewTypes.SWIPE] = element.querySelector('.view-modes-menu .swipe');
+    replacedImageDiff.viewModesEls[viewTypes.ONION_SKIN] = element.querySelector('.view-modes-menu .onion-skin');
+  }
+
+  function setupImageEls() {
+    replacedImageDiff.imageEls = [];
+    replacedImageDiff.imageEls[viewTypes.TWO_UP] = element.querySelector('.two-up img');
+    replacedImageDiff.imageEls[viewTypes.SWIPE] = element.querySelector('.swipe img');
+    replacedImageDiff.imageEls[viewTypes.ONION_SKIN] = element.querySelector('.onion-skin img');
+  }
+
+  it('should extend ImageDiff', () => {
+    replacedImageDiff = new ReplacedImageDiff(element);
+    expect(replacedImageDiff instanceof ImageDiff).toEqual(true);
+  });
+
+  describe('init', () => {
+    beforeEach(() => {
+      spyOn(ReplacedImageDiff.prototype, 'bindEvents').and.callFake(() => {});
+      spyOn(ReplacedImageDiff.prototype, 'generateImageEls').and.callFake(() => {});
+
+      replacedImageDiff = new ReplacedImageDiff(element);
+      replacedImageDiff.init();
+    });
+
+    it('should set imageFrameEls', () => {
+      const { imageFrameEls } = replacedImageDiff;
+      expect(imageFrameEls).toBeDefined();
+      expect(imageFrameEls[viewTypes.TWO_UP]).toEqual(element.querySelector('.two-up .js-image-frame'));
+      expect(imageFrameEls[viewTypes.SWIPE]).toEqual(element.querySelector('.swipe .js-image-frame'));
+      expect(imageFrameEls[viewTypes.ONION_SKIN]).toEqual(element.querySelector('.onion-skin .js-image-frame'));
+    });
+
+    it('should set viewModesEls', () => {
+      const { viewModesEls } = replacedImageDiff;
+      expect(viewModesEls).toBeDefined();
+      expect(viewModesEls[viewTypes.TWO_UP]).toEqual(element.querySelector('.view-modes-menu .two-up'));
+      expect(viewModesEls[viewTypes.SWIPE]).toEqual(element.querySelector('.view-modes-menu .swipe'));
+      expect(viewModesEls[viewTypes.ONION_SKIN]).toEqual(element.querySelector('.view-modes-menu .onion-skin'));
+    });
+
+    it('should generateImageEls', () => {
+      expect(ReplacedImageDiff.prototype.generateImageEls).toHaveBeenCalled();
+    });
+
+    it('should bindEvents', () => {
+      expect(ReplacedImageDiff.prototype.bindEvents).toHaveBeenCalled();
+    });
+
+    describe('currentView', () => {
+      it('should set currentView', () => {
+        replacedImageDiff.init(viewTypes.ONION_SKIN);
+        expect(replacedImageDiff.currentView).toEqual(viewTypes.ONION_SKIN);
+      });
+
+      it('should default to viewTypes.TWO_UP', () => {
+        expect(replacedImageDiff.currentView).toEqual(viewTypes.TWO_UP);
+      });
+    });
+  });
+
+  describe('generateImageEls', () => {
+    beforeEach(() => {
+      spyOn(ReplacedImageDiff.prototype, 'bindEvents').and.callFake(() => {});
+
+      replacedImageDiff = new ReplacedImageDiff(element, {
+        canCreateNote: false,
+        renderCommentBadge: false,
+      });
+
+      setupImageFrameEls();
+    });
+
+    it('should set imageEls', () => {
+      replacedImageDiff.generateImageEls();
+      const { imageEls } = replacedImageDiff;
+      expect(imageEls).toBeDefined();
+      expect(imageEls[viewTypes.TWO_UP]).toEqual(element.querySelector('.two-up img'));
+      expect(imageEls[viewTypes.SWIPE]).toEqual(element.querySelector('.swipe img'));
+      expect(imageEls[viewTypes.ONION_SKIN]).toEqual(element.querySelector('.onion-skin img'));
+    });
+  });
+
+  describe('bindEvents', () => {
+    beforeEach(() => {
+      spyOn(ImageDiff.prototype, 'bindEvents').and.callFake(() => {});
+      replacedImageDiff = new ReplacedImageDiff(element);
+
+      setupViewModesEls();
+    });
+
+    it('should call super.bindEvents', () => {
+      replacedImageDiff.bindEvents();
+      expect(ImageDiff.prototype.bindEvents).toHaveBeenCalled();
+    });
+
+    it('should register click eventlistener to 2-up view mode', (done) => {
+      spyOn(ReplacedImageDiff.prototype, 'changeView').and.callFake((viewMode) => {
+        expect(viewMode).toEqual(viewTypes.TWO_UP);
+        done();
+      });
+
+      replacedImageDiff.bindEvents();
+      replacedImageDiff.viewModesEls[viewTypes.TWO_UP].click();
+    });
+
+    it('should register click eventlistener to swipe view mode', (done) => {
+      spyOn(ReplacedImageDiff.prototype, 'changeView').and.callFake((viewMode) => {
+        expect(viewMode).toEqual(viewTypes.SWIPE);
+        done();
+      });
+
+      replacedImageDiff.bindEvents();
+      replacedImageDiff.viewModesEls[viewTypes.SWIPE].click();
+    });
+
+    it('should register click eventlistener to onion skin view mode', (done) => {
+      spyOn(ReplacedImageDiff.prototype, 'changeView').and.callFake((viewMode) => {
+        expect(viewMode).toEqual(viewTypes.SWIPE);
+        done();
+      });
+
+      replacedImageDiff.bindEvents();
+      replacedImageDiff.viewModesEls[viewTypes.SWIPE].click();
+    });
+  });
+
+  describe('getters', () => {
+    describe('imageEl', () => {
+      beforeEach(() => {
+        replacedImageDiff = new ReplacedImageDiff(element);
+        replacedImageDiff.currentView = viewTypes.TWO_UP;
+        setupImageEls();
+      });
+
+      it('should return imageEl based on currentView', () => {
+        expect(replacedImageDiff.imageEl).toEqual(element.querySelector('.two-up img'));
+
+        replacedImageDiff.currentView = viewTypes.SWIPE;
+        expect(replacedImageDiff.imageEl).toEqual(element.querySelector('.swipe img'));
+      });
+    });
+
+    describe('imageFrameEl', () => {
+      beforeEach(() => {
+        replacedImageDiff = new ReplacedImageDiff(element);
+        replacedImageDiff.currentView = viewTypes.TWO_UP;
+        setupImageFrameEls();
+      });
+
+      it('should return imageFrameEl based on currentView', () => {
+        expect(replacedImageDiff.imageFrameEl).toEqual(element.querySelector('.two-up .js-image-frame'));
+
+        replacedImageDiff.currentView = viewTypes.ONION_SKIN;
+        expect(replacedImageDiff.imageFrameEl).toEqual(element.querySelector('.onion-skin .js-image-frame'));
+      });
+    });
+  });
+
+  describe('changeView', () => {
+    beforeEach(() => {
+      replacedImageDiff = new ReplacedImageDiff(element);
+      spyOn(imageDiffHelper, 'removeCommentIndicator').and.returnValue({
+        removed: false,
+      });
+      setupImageFrameEls();
+    });
+
+    describe('invalid viewType', () => {
+      beforeEach(() => {
+        replacedImageDiff.changeView('some-view-name');
+      });
+
+      it('should not call removeCommentIndicator', () => {
+        expect(imageDiffHelper.removeCommentIndicator).not.toHaveBeenCalled();
+      });
+    });
+
+    describe('valid viewType', () => {
+      beforeEach(() => {
+        jasmine.clock().install();
+        spyOn(ReplacedImageDiff.prototype, 'renderNewView').and.callFake(() => {});
+        replacedImageDiff.changeView(viewTypes.ONION_SKIN);
+      });
+
+      afterEach(() => {
+        jasmine.clock().uninstall();
+      });
+
+      it('should call removeCommentIndicator', () => {
+        expect(imageDiffHelper.removeCommentIndicator).toHaveBeenCalled();
+      });
+
+      it('should update currentView to newView', () => {
+        expect(replacedImageDiff.currentView).toEqual(viewTypes.ONION_SKIN);
+      });
+
+      it('should clear imageBadges', () => {
+        expect(replacedImageDiff.imageBadges.length).toEqual(0);
+      });
+
+      it('should call renderNewView', () => {
+        jasmine.clock().tick(251);
+        expect(replacedImageDiff.renderNewView).toHaveBeenCalled();
+      });
+    });
+  });
+
+  describe('renderNewView', () => {
+    beforeEach(() => {
+      replacedImageDiff = new ReplacedImageDiff(element);
+    });
+
+    it('should call renderBadges', () => {
+      spyOn(ReplacedImageDiff.prototype, 'renderBadges').and.callFake(() => {});
+
+      replacedImageDiff.renderNewView({
+        removed: false,
+      });
+
+      expect(replacedImageDiff.renderBadges).toHaveBeenCalled();
+    });
+
+    describe('removeIndicator', () => {
+      const indicator = {
+        removed: true,
+        x: 0,
+        y: 1,
+        image: {
+          width: 50,
+          height: 100,
+        },
+      };
+
+      beforeEach(() => {
+        setupImageEls();
+        setupImageFrameEls();
+      });
+
+      it('should pass showCommentIndicator normalized indicator values', (done) => {
+        spyOn(imageDiffHelper, 'showCommentIndicator').and.callFake(() => {});
+        spyOn(imageDiffHelper, 'resizeCoordinatesToImageElement').and.callFake((imageEl, meta) => {
+          expect(meta.x).toEqual(indicator.x);
+          expect(meta.y).toEqual(indicator.y);
+          expect(meta.width).toEqual(indicator.image.width);
+          expect(meta.height).toEqual(indicator.image.height);
+          done();
+        });
+        replacedImageDiff.renderNewView(indicator);
+      });
+
+      it('should call showCommentIndicator', (done) => {
+        const normalized = {
+          normalized: true,
+        };
+        spyOn(imageDiffHelper, 'resizeCoordinatesToImageElement').and.returnValue(normalized);
+        spyOn(imageDiffHelper, 'showCommentIndicator').and.callFake((imageFrameEl, normalizedIndicator) => {
+          expect(normalizedIndicator).toEqual(normalized);
+          done();
+        });
+        replacedImageDiff.renderNewView(indicator);
+      });
+    });
+  });
+});
diff --git a/spec/javascripts/image_diff/view_types_spec.js b/spec/javascripts/image_diff/view_types_spec.js
new file mode 100644
index 00000000000..e9639f46497
--- /dev/null
+++ b/spec/javascripts/image_diff/view_types_spec.js
@@ -0,0 +1,24 @@
+import { viewTypes, isValidViewType } from '~/image_diff/view_types';
+
+describe('viewTypes', () => {
+  describe('isValidViewType', () => {
+    it('should return true for TWO_UP', () => {
+      expect(isValidViewType(viewTypes.TWO_UP)).toEqual(true);
+    });
+
+    it('should return true for SWIPE', () => {
+      expect(isValidViewType(viewTypes.SWIPE)).toEqual(true);
+    });
+
+    it('should return true for ONION_SKIN', () => {
+      expect(isValidViewType(viewTypes.ONION_SKIN)).toEqual(true);
+    });
+
+    it('should return false for non view types', () => {
+      expect(isValidViewType('some-view-type')).toEqual(false);
+      expect(isValidViewType(null)).toEqual(false);
+      expect(isValidViewType(undefined)).toEqual(false);
+      expect(isValidViewType('')).toEqual(false);
+    });
+  });
+});
diff --git a/spec/javascripts/lib/utils/image_utility_spec.js b/spec/javascripts/lib/utils/image_utility_spec.js
new file mode 100644
index 00000000000..75addfcc833
--- /dev/null
+++ b/spec/javascripts/lib/utils/image_utility_spec.js
@@ -0,0 +1,32 @@
+import * as imageUtility from '~/lib/utils/image_utility';
+
+describe('imageUtility', () => {
+  describe('isImageLoaded', () => {
+    it('should return false when image.complete is false', () => {
+      const element = {
+        complete: false,
+        naturalHeight: 100,
+      };
+
+      expect(imageUtility.isImageLoaded(element)).toEqual(false);
+    });
+
+    it('should return false when naturalHeight = 0', () => {
+      const element = {
+        complete: true,
+        naturalHeight: 0,
+      };
+
+      expect(imageUtility.isImageLoaded(element)).toEqual(false);
+    });
+
+    it('should return true when image.complete and naturalHeight != 0', () => {
+      const element = {
+        complete: true,
+        naturalHeight: 100,
+      };
+
+      expect(imageUtility.isImageLoaded(element)).toEqual(true);
+    });
+  });
+});
diff --git a/spec/lib/gitlab/diff/formatters/image_formatter_spec.rb b/spec/lib/gitlab/diff/formatters/image_formatter_spec.rb
new file mode 100644
index 00000000000..2f99febe04e
--- /dev/null
+++ b/spec/lib/gitlab/diff/formatters/image_formatter_spec.rb
@@ -0,0 +1,20 @@
+require 'spec_helper'
+
+describe Gitlab::Diff::Formatters::ImageFormatter do
+  it_behaves_like "position formatter" do
+    let(:base_attrs) do
+      {
+        base_sha: 123,
+        start_sha: 456,
+        head_sha: 789,
+        old_path: 'old_image.png',
+        new_path: 'new_image.png',
+        position_type: 'image'
+      }
+    end
+
+    let(:attrs) do
+      base_attrs.merge(width: 100, height: 100, x: 1, y: 2)
+    end
+  end
+end
diff --git a/spec/lib/gitlab/diff/formatters/text_formatter_spec.rb b/spec/lib/gitlab/diff/formatters/text_formatter_spec.rb
new file mode 100644
index 00000000000..897dc917f6a
--- /dev/null
+++ b/spec/lib/gitlab/diff/formatters/text_formatter_spec.rb
@@ -0,0 +1,42 @@
+require 'spec_helper'
+
+describe Gitlab::Diff::Formatters::TextFormatter do
+  let!(:base) do
+    {
+      base_sha: 123,
+      start_sha: 456,
+      head_sha: 789,
+      old_path: 'old_path.txt',
+      new_path: 'new_path.txt'
+    }
+  end
+
+  let!(:complete) do
+    base.merge(old_line: 1, new_line: 2)
+  end
+
+  it_behaves_like "position formatter" do
+    let(:base_attrs) { base }
+
+    let(:attrs) { complete }
+  end
+
+  # Specific text formatter examples
+  let!(:formatter) { described_class.new(attrs) }
+
+  describe '#line_age' do
+    subject { formatter.line_age }
+
+    context ' when there is only new_line' do
+      let(:attrs) { base.merge(new_line: 1) }
+
+      it { is_expected.to eq('new') }
+    end
+
+    context ' when there is only old_line' do
+      let(:attrs) { base.merge(old_line: 1) }
+
+      it { is_expected.to eq('old') }
+    end
+  end
+end
diff --git a/spec/lib/gitlab/diff/position_spec.rb b/spec/lib/gitlab/diff/position_spec.rb
index 7798736a4dc..9bf54fdecc4 100644
--- a/spec/lib/gitlab/diff/position_spec.rb
+++ b/spec/lib/gitlab/diff/position_spec.rb
@@ -5,7 +5,7 @@ describe Gitlab::Diff::Position do
 
   let(:project) { create(:project, :repository) }
 
-  describe "position for an added file" do
+  describe "position for an added text file" do
     let(:commit) { project.commit("2ea1f3dec713d940208fb5ce4a38765ecb5d3f73") }
 
     subject do
@@ -47,6 +47,31 @@ describe Gitlab::Diff::Position do
     end
   end
 
+  describe "position for an added image file" do
+    let(:commit) { project.commit("33f3729a45c02fc67d00adb1b8bca394b0e761d9") }
+
+    subject do
+      described_class.new(
+        old_path: "files/images/6049019_460s.jpg",
+        new_path: "files/images/6049019_460s.jpg",
+        width: 100,
+        height: 100,
+        x: 1,
+        y: 100,
+        diff_refs: commit.diff_refs,
+        position_type: "image"
+      )
+    end
+
+    it "returns the correct diff file" do
+      diff_file = subject.diff_file(project.repository)
+
+      expect(diff_file.new_file?).to be true
+      expect(diff_file.new_path).to eq(subject.new_path)
+      expect(diff_file.diff_refs).to eq(subject.diff_refs)
+    end
+  end
+
   describe "position for a changed file" do
     let(:commit) { project.commit("570e7b2abdd848b95f2f578043fc23bd6f6fd24d") }
 
@@ -468,26 +493,54 @@ describe Gitlab::Diff::Position do
   end
 
   describe "#to_json" do
-    let(:hash) do
-      {
-        old_path: "files/ruby/popen.rb",
-        new_path: "files/ruby/popen.rb",
-        old_line: nil,
-        new_line: 14,
-        base_sha: nil,
-        head_sha: nil,
-        start_sha: nil
-      }
+    shared_examples "diff position json" do
+      it "returns the position as JSON" do
+        expect(JSON.parse(diff_position.to_json)).to eq(hash.stringify_keys)
+      end
+
+      it "works when nested under another hash" do
+        expect(JSON.parse(JSON.generate(pos: diff_position))).to eq('pos' => hash.stringify_keys)
+      end
     end
 
-    let(:diff_position) { described_class.new(hash) }
+    context "for text positon" do
+      let(:hash) do
+        {
+          old_path: "files/ruby/popen.rb",
+          new_path: "files/ruby/popen.rb",
+          old_line: nil,
+          new_line: 14,
+          base_sha: nil,
+          head_sha: nil,
+          start_sha: nil,
+          position_type: "text"
+        }
+      end
+
+      let(:diff_position) { described_class.new(hash) }
 
-    it "returns the position as JSON" do
-      expect(JSON.parse(diff_position.to_json)).to eq(hash.stringify_keys)
+      it_behaves_like "diff position json"
     end
 
-    it "works when nested under another hash" do
-      expect(JSON.parse(JSON.generate(pos: diff_position))).to eq('pos' => hash.stringify_keys)
+    context "for image positon" do
+      let(:hash) do
+        {
+          old_path: "files/any.img",
+          new_path: "files/any.img",
+          base_sha: nil,
+          head_sha: nil,
+          start_sha: nil,
+          width: 100,
+          height: 100,
+          x: 1,
+          y: 100,
+          position_type: "image"
+        }
+      end
+
+      let(:diff_position) { described_class.new(hash) }
+
+      it_behaves_like "diff position json"
     end
   end
 end
diff --git a/spec/lib/gitlab/diff/position_tracer_spec.rb b/spec/lib/gitlab/diff/position_tracer_spec.rb
index 4fa30d8df8b..e5138705443 100644
--- a/spec/lib/gitlab/diff/position_tracer_spec.rb
+++ b/spec/lib/gitlab/diff/position_tracer_spec.rb
@@ -71,6 +71,10 @@ describe Gitlab::Diff::PositionTracer do
     Gitlab::Diff::DiffRefs.new(base_sha: base_commit.id, head_sha: head_commit.id)
   end
 
+  def text_position_attrs
+    [:old_line, :new_line]
+  end
+
   def position(attrs = {})
     attrs.reverse_merge!(
       diff_refs: old_diff_refs
@@ -91,7 +95,11 @@ describe Gitlab::Diff::PositionTracer do
         expect(new_position.diff_refs).to eq(new_diff_refs)
 
         attrs.each do |attr, value|
-          expect(new_position.send(attr)).to eq(value)
+          if text_position_attrs.include?(attr)
+            expect(new_position.formatter.send(attr)).to eq(value)
+          else
+            expect(new_position.send(attr)).to eq(value)
+          end
         end
       end
     end
@@ -110,7 +118,11 @@ describe Gitlab::Diff::PositionTracer do
         expect(change_position.diff_refs).to eq(change_diff_refs)
 
         attrs.each do |attr, value|
-          expect(change_position.send(attr)).to eq(value)
+          if text_position_attrs.include?(attr)
+            expect(change_position.formatter.send(attr)).to eq(value)
+          else
+            expect(change_position.send(attr)).to eq(value)
+          end
         end
       end
     end
diff --git a/spec/models/diff_note_spec.rb b/spec/models/diff_note_spec.rb
index 4aa9ec789a3..eb0a3e9e0d3 100644
--- a/spec/models/diff_note_spec.rb
+++ b/spec/models/diff_note_spec.rb
@@ -3,7 +3,7 @@ require 'spec_helper'
 describe DiffNote do
   include RepoHelpers
 
-  let(:merge_request) { create(:merge_request) }
+  let!(:merge_request) { create(:merge_request) }
   let(:project) { merge_request.project }
   let(:commit) { project.commit(sample_commit.id) }
 
@@ -98,14 +98,14 @@ describe DiffNote do
       diff_line = subject.diff_line
 
       expect(diff_line.added?).to be true
-      expect(diff_line.new_line).to eq(position.new_line)
+      expect(diff_line.new_line).to eq(position.formatter.new_line)
       expect(diff_line.text).to eq("+    vars = {")
     end
   end
 
   describe "#line_code" do
     it "returns the correct line code" do
-      line_code = Gitlab::Diff::LineCode.generate(position.file_path, position.new_line, 15)
+      line_code = Gitlab::Diff::LineCode.generate(position.file_path, position.formatter.new_line, 15)
 
       expect(subject.line_code).to eq(line_code)
     end
@@ -255,4 +255,38 @@ describe DiffNote do
       end
     end
   end
+
+  describe "image diff notes" do
+    let(:path) { "files/images/any_image.png" }
+
+    let!(:position) do
+      Gitlab::Diff::Position.new(
+        old_path: path,
+        new_path: path,
+        width: 10,
+        height: 10,
+        x: 1,
+        y: 1,
+        diff_refs: merge_request.diff_refs,
+        position_type: "image"
+      )
+    end
+
+    describe "validations" do
+      subject { build(:diff_note_on_merge_request, project: project, position: position, noteable: merge_request) }
+
+      it { is_expected.not_to validate_presence_of(:line_code) }
+
+      it "does not validate diff line" do
+        diff_line = subject.diff_line
+
+        expect(diff_line).to be nil
+        expect(subject).to be_valid
+      end
+    end
+
+    it "returns true for on_image?" do
+      expect(subject.on_image?).to be_truthy
+    end
+  end
 end
diff --git a/spec/models/note_spec.rb b/spec/models/note_spec.rb
index b214074fdce..1ecb50586c7 100644
--- a/spec/models/note_spec.rb
+++ b/spec/models/note_spec.rb
@@ -314,6 +314,56 @@ describe Note do
         expect(subject[active_diff_note1.line_code].first.id).to eq(active_diff_note1.discussion_id)
         expect(subject[active_diff_note3.line_code].first.id).to eq(active_diff_note3.discussion_id)
       end
+
+      context 'with image discussions' do
+        let(:merge_request2) { create(:merge_request_with_diffs, :with_image_diffs, source_project: project, title: "Added images and changes") }
+        let(:image_path) { "files/images/ee_repo_logo.png" }
+        let(:text_path) { "bar/branch-test.txt" }
+        let!(:image_note) { create(:diff_note_on_merge_request, project: project, noteable: merge_request2, position: image_position) }
+        let!(:text_note) { create(:diff_note_on_merge_request, project: project, noteable: merge_request2, position: text_position) }
+
+        let(:image_position) do
+          Gitlab::Diff::Position.new(
+            old_path: image_path,
+            new_path: image_path,
+            width: 100,
+            height: 100,
+            x: 1,
+            y: 1,
+            position_type: "image",
+            diff_refs: merge_request2.diff_refs
+          )
+        end
+
+        let(:text_position) do
+          Gitlab::Diff::Position.new(
+            old_path: text_path,
+            new_path: text_path,
+            old_line: nil,
+            new_line: 2,
+            position_type: "text",
+            diff_refs: merge_request2.diff_refs
+          )
+        end
+
+        it "groups image discussions by file identifier" do
+          diff_discussion = DiffDiscussion.new([image_note])
+
+          discussions = merge_request2.notes.grouped_diff_discussions
+
+          expect(discussions.size).to eq(2)
+          expect(discussions[image_note.diff_file.new_path]).to include(diff_discussion)
+        end
+
+        it "groups text discussions by line code" do
+          diff_discussion = DiffDiscussion.new([text_note])
+
+          discussions = merge_request2.notes.grouped_diff_discussions
+
+          expect(discussions.size).to eq(2)
+          expect(discussions[text_note.line_code]).to include(diff_discussion)
+        end
+      end
     end
 
     context 'diff discussions for older diff refs' do
diff --git a/spec/services/discussions/update_diff_position_service_spec.rb b/spec/services/discussions/update_diff_position_service_spec.rb
index 82b156f5ebe..2b84206318f 100644
--- a/spec/services/discussions/update_diff_position_service_spec.rb
+++ b/spec/services/discussions/update_diff_position_service_spec.rb
@@ -164,8 +164,8 @@ describe Discussions::UpdateDiffPositionService do
         change_position = discussion.change_position
         expect(change_position.start_sha).to eq(old_diff_refs.head_sha)
         expect(change_position.head_sha).to eq(new_diff_refs.head_sha)
-        expect(change_position.old_line).to eq(9)
-        expect(change_position.new_line).to be_nil
+        expect(change_position.formatter.old_line).to eq(9)
+        expect(change_position.formatter.new_line).to be_nil
       end
 
       it 'creates a system discussion' do
@@ -184,7 +184,7 @@ describe Discussions::UpdateDiffPositionService do
 
         expect(discussion.original_position).to eq(old_position)
         expect(discussion.position).not_to eq(old_position)
-        expect(discussion.position.new_line).to eq(22)
+        expect(discussion.position.formatter.new_line).to eq(22)
       end
 
       context 'when the resolve_outdated_diff_discussions setting is set' do
diff --git a/spec/support/features/discussion_comments_shared_example.rb b/spec/support/features/discussion_comments_shared_example.rb
index 81cb94ab8c4..9f05cabf7ae 100644
--- a/spec/support/features/discussion_comments_shared_example.rb
+++ b/spec/support/features/discussion_comments_shared_example.rb
@@ -71,7 +71,7 @@ shared_examples 'discussion comments' do |resource_name|
       expect(page).not_to have_selector menu_selector
 
       find(toggle_selector).click
-      find('body').click
+      find('body').trigger 'click'
 
       expect(page).not_to have_selector menu_selector
     end
diff --git a/spec/support/shared_examples/position_formatters.rb b/spec/support/shared_examples/position_formatters.rb
new file mode 100644
index 00000000000..ffc9456dbc7
--- /dev/null
+++ b/spec/support/shared_examples/position_formatters.rb
@@ -0,0 +1,43 @@
+shared_examples_for "position formatter" do
+  let(:formatter) { described_class.new(attrs) }
+
+  describe '#key' do
+    let(:key) { [123, 456, 789, Digest::SHA1.hexdigest(formatter.old_path), Digest::SHA1.hexdigest(formatter.new_path), 1, 2] }
+
+    subject { formatter.key }
+
+    it { is_expected.to eq(key) }
+  end
+
+  describe '#complete?' do
+    subject { formatter.complete? }
+
+    context 'when there are missing key attributes' do
+      it { is_expected.to be_truthy }
+    end
+
+    context 'when old_line and new_line are nil' do
+      let(:attrs) { base_attrs }
+
+      it { is_expected.to be_falsy }
+    end
+  end
+
+  describe '#to_h' do
+    let(:formatter_hash) do
+      attrs.merge(position_type: base_attrs[:position_type] || 'text' )
+    end
+
+    subject { formatter.to_h }
+
+    it { is_expected.to eq(formatter_hash) }
+  end
+
+  describe '#==' do
+    subject { formatter }
+
+    let(:other_formatter) { described_class.new(attrs) }
+
+    it { is_expected.to eq(other_formatter) }
+  end
+end
diff --git a/spec/support/test_env.rb b/spec/support/test_env.rb
index 79395f4c564..a27bfdee3d2 100644
--- a/spec/support/test_env.rb
+++ b/spec/support/test_env.rb
@@ -46,7 +46,8 @@ module TestEnv
     'v1.1.0'                             => 'b83d6e3',
     'add-ipython-files'                  => '93ee732',
     'add-pdf-file'                       => 'e774ebd',
-    'add-pdf-text-binary'                => '79faa7b'
+    'add-pdf-text-binary'                => '79faa7b',
+    'add_images_and_changes'             => '010d106'
   }.freeze
 
   # gitlab-test-fork is a fork of gitlab-fork, but we don't necessarily