diff options
Diffstat (limited to 'gst/dvbsubenc/libimagequant/libimagequant.c')
| -rw-r--r-- | gst/dvbsubenc/libimagequant/libimagequant.c | 2054 |
1 files changed, 2054 insertions, 0 deletions
diff --git a/gst/dvbsubenc/libimagequant/libimagequant.c b/gst/dvbsubenc/libimagequant/libimagequant.c new file mode 100644 index 000000000..1eaccbf9e --- /dev/null +++ b/gst/dvbsubenc/libimagequant/libimagequant.c @@ -0,0 +1,2054 @@ +/* pngquant.c - quantize the colors in an alphamap down to a specified number +** +** Copyright (C) 1989, 1991 by Jef Poskanzer. +** Copyright (C) 1997, 2000, 2002 by Greg Roelofs; based on an idea by +** Stefan Schneider. +** © 2009-2013 by Kornel Lesinski. +** +** Permission to use, copy, modify, and distribute this software and its +** documentation for any purpose and without fee is hereby granted, provided +** that the above copyright notice appear in all copies and that both that +** copyright notice and this permission notice appear in supporting +** documentation. This software is provided "as is" without express or +** implied warranty. +*/ + +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <stdarg.h> +#include <stdbool.h> +#include <stdint.h> +#include <limits.h> + +#if !(defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199900L) && !(defined(_MSC_VER) && _MSC_VER >= 1800) +#error "This program requires C99, e.g. -std=c99 switch in GCC or it requires MSVC 18.0 or higher." +#error "Ignore torrent of syntax errors that may follow. It's only because compiler is set to use too old C version." +#endif + +#ifdef _OPENMP +#include <omp.h> +#else +#define omp_get_max_threads() 1 +#define omp_get_thread_num() 0 +#endif + +#include "libimagequant.h" + +#include "pam.h" +#include "mediancut.h" +#include "nearest.h" +#include "blur.h" +#include "viter.h" + +#define LIQ_HIGH_MEMORY_LIMIT (1<<26) /* avoid allocating buffers larger than 64MB */ + +// each structure has a pointer as a unique identifier that allows type checking at run time +static const char *const liq_attr_magic = "liq_attr", *const liq_image_magic = + "liq_image", *const liq_result_magic = + "liq_result", *const liq_remapping_result_magic = + "liq_remapping_result", *const liq_freed_magic = "free"; +#define CHECK_STRUCT_TYPE(attr, kind) liq_crash_if_invalid_handle_pointer_given((const liq_attr*)attr, kind ## _magic) +#define CHECK_USER_POINTER(ptr) liq_crash_if_invalid_pointer_given(ptr) + +struct liq_attr +{ + const char *magic_header; + void *(*malloc) (size_t); + void (*free) (void *); + + double target_mse, max_mse, voronoi_iteration_limit; + float min_opaque_val; + unsigned int max_colors, max_histogram_entries; + unsigned int min_posterization_output /* user setting */ , + min_posterization_input /* speed setting */ ; + unsigned int voronoi_iterations, feedback_loop_trials; + bool last_index_transparent, use_contrast_maps, use_dither_map, fast_palette; + unsigned int speed; + liq_log_callback_function *log_callback; + void *log_callback_user_info; + liq_log_flush_callback_function *log_flush_callback; + void *log_flush_callback_user_info; +}; + +struct liq_image +{ + const char *magic_header; + void *(*malloc) (size_t); + void (*free) (void *); + + f_pixel *f_pixels; + rgba_pixel **rows; + double gamma; + unsigned int width, height; + unsigned char *noise, *edges, *dither_map; + rgba_pixel *pixels, *temp_row; + f_pixel *temp_f_row; + liq_image_get_rgba_row_callback *row_callback; + void *row_callback_user_info; + float min_opaque_val; + f_pixel fixed_colors[256]; + unsigned short fixed_colors_count; + bool free_pixels, free_rows, free_rows_internal; +}; + +typedef struct liq_remapping_result +{ + const char *magic_header; + void *(*malloc) (size_t); + void (*free) (void *); + + unsigned char *pixels; + colormap *palette; + liq_palette int_palette; + double gamma, palette_error; + float dither_level; + bool use_dither_map; +} liq_remapping_result; + +struct liq_result +{ + const char *magic_header; + void *(*malloc) (size_t); + void (*free) (void *); + + liq_remapping_result *remapping; + colormap *palette; + liq_palette int_palette; + float dither_level; + double gamma, palette_error; + int min_posterization_output; + bool use_dither_map, fast_palette; +}; + +static liq_result *pngquant_quantize (histogram * hist, + const liq_attr * options, const liq_image * img); +static void modify_alpha (liq_image * input_image, + rgba_pixel * const row_pixels); +static void contrast_maps (liq_image * image); +static histogram *get_histogram (liq_image * input_image, + const liq_attr * options); +static const rgba_pixel *liq_image_get_row_rgba (liq_image * input_image, + unsigned int row); +static const f_pixel *liq_image_get_row_f (liq_image * input_image, + unsigned int row); +static void liq_remapping_result_destroy (liq_remapping_result * result); + +static void +liq_verbose_printf (const liq_attr * context, const char *fmt, ...) +{ + if (context->log_callback) { + va_list va; + int required_space; + char *buf; + + va_start (va, fmt); + required_space = vsnprintf (NULL, 0, fmt, va) + 1; // +\0 + va_end (va); + + buf = g_alloca (required_space); + + va_start (va, fmt); + vsnprintf (buf, required_space, fmt, va); + va_end (va); + + context->log_callback (context, buf, context->log_callback_user_info); + } +} + +inline static void +verbose_print (const liq_attr * attr, const char *msg) +{ + if (attr->log_callback) { + attr->log_callback (attr, msg, attr->log_callback_user_info); + } +} + +static void +liq_verbose_printf_flush (liq_attr * attr) +{ + if (attr->log_flush_callback) { + attr->log_flush_callback (attr, attr->log_flush_callback_user_info); + } +} + +#if USE_SSE +inline static bool +is_sse_available (void) +{ +#if (defined(__x86_64__) || defined(__amd64)) + return true; +#else + int a, b, c, d; + cpuid (1, a, b, c, d); + return d & (1 << 25); // edx bit 25 is set when SSE is present +#endif +} +#endif + +/* make it clear in backtrace when user-supplied handle points to invalid memory */ +NEVER_INLINE LIQ_EXPORT bool liq_crash_if_invalid_handle_pointer_given (const + liq_attr * user_supplied_pointer, const char *const expected_magic_header); +LIQ_EXPORT bool +liq_crash_if_invalid_handle_pointer_given (const liq_attr * + user_supplied_pointer, const char *const expected_magic_header) +{ + if (!user_supplied_pointer) { + return false; + } + + if (user_supplied_pointer->magic_header == liq_freed_magic) { + fprintf (stderr, "%s used after being freed", expected_magic_header); + // this is not normal error handling, this is programmer error that should crash the program. + // program cannot safely continue if memory has been used after it's been freed. + // abort() is nasty, but security vulnerability may be worse. + abort (); + } + + return user_supplied_pointer->magic_header == expected_magic_header; +} + +NEVER_INLINE LIQ_EXPORT bool liq_crash_if_invalid_pointer_given (void *pointer); +LIQ_EXPORT bool +liq_crash_if_invalid_pointer_given (void *pointer) +{ + char test_access; + + if (!pointer) { + return false; + } + // Force a read from the given (potentially invalid) memory location in order to check early whether this crashes the program or not. + // It doesn't matter what value is read, the code here is just to shut the compiler up about unused read. + test_access = *((volatile char *) pointer); + return test_access || true; +} + +static void +liq_log_error (const liq_attr * attr, const char *msg) +{ + if (!CHECK_STRUCT_TYPE (attr, liq_attr)) + return; + liq_verbose_printf (attr, " error: %s", msg); +} + +static double +quality_to_mse (long quality) +{ + const double extra_low_quality_fudge = + MAX (0, 0.016 / (0.001 + quality) - 0.001); + if (quality == 0) { + return MAX_DIFF; + } + if (quality == 100) { + return 0; + } + // curve fudged to be roughly similar to quality of libjpeg + // except lowest 10 for really low number of colors + return extra_low_quality_fudge + 2.5 / pow (210.0 + quality, + 1.2) * (100.1 - quality) / 100.0; +} + +static unsigned int +mse_to_quality (double mse) +{ + int i; + for (i = 100; i > 0; i--) { + if (mse <= quality_to_mse (i) + 0.000001) { // + epsilon for floating point errors + return i; + } + } + return 0; +} + +LIQ_EXPORT liq_error +liq_set_quality (liq_attr * attr, int minimum, int target) +{ + if (!CHECK_STRUCT_TYPE (attr, liq_attr)) + return LIQ_INVALID_POINTER; + if (target < 0 || target > 100 || target < minimum || minimum < 0) + return LIQ_VALUE_OUT_OF_RANGE; + + attr->target_mse = quality_to_mse (target); + attr->max_mse = quality_to_mse (minimum); + return LIQ_OK; +} + +LIQ_EXPORT int +liq_get_min_quality (const liq_attr * attr) +{ + if (!CHECK_STRUCT_TYPE (attr, liq_attr)) + return -1; + return mse_to_quality (attr->max_mse); +} + +LIQ_EXPORT int +liq_get_max_quality (const liq_attr * attr) +{ + if (!CHECK_STRUCT_TYPE (attr, liq_attr)) + return -1; + return mse_to_quality (attr->target_mse); +} + + +LIQ_EXPORT liq_error +liq_set_max_colors (liq_attr * attr, int colors) +{ + if (!CHECK_STRUCT_TYPE (attr, liq_attr)) + return LIQ_INVALID_POINTER; + if (colors < 2 || colors > 256) + return LIQ_VALUE_OUT_OF_RANGE; + + attr->max_colors = colors; + return LIQ_OK; +} + +LIQ_EXPORT int +liq_get_max_colors (const liq_attr * attr) +{ + if (!CHECK_STRUCT_TYPE (attr, liq_attr)) + return -1; + + return attr->max_colors; +} + +LIQ_EXPORT liq_error +liq_set_min_posterization (liq_attr * attr, int bits) +{ + if (!CHECK_STRUCT_TYPE (attr, liq_attr)) + return LIQ_INVALID_POINTER; + if (bits < 0 || bits > 4) + return LIQ_VALUE_OUT_OF_RANGE; + + attr->min_posterization_output = bits; + return LIQ_OK; +} + +LIQ_EXPORT int +liq_get_min_posterization (const liq_attr * attr) +{ + if (!CHECK_STRUCT_TYPE (attr, liq_attr)) + return -1; + + return attr->min_posterization_output; +} + +LIQ_EXPORT liq_error +liq_set_speed (liq_attr * attr, int speed) +{ + int iterations; + + if (!CHECK_STRUCT_TYPE (attr, liq_attr)) + return LIQ_INVALID_POINTER; + if (speed < 1 || speed > 10) + return LIQ_VALUE_OUT_OF_RANGE; + + iterations = MAX (8 - speed, 0); + iterations += iterations * iterations / 2; + attr->voronoi_iterations = iterations; + attr->voronoi_iteration_limit = 1.0 / (double) (1 << (23 - speed)); + attr->feedback_loop_trials = MAX (56 - 9 * speed, 0); + + attr->max_histogram_entries = (1 << 17) + (1 << 18) * (10 - speed); + attr->min_posterization_input = (speed >= 8) ? 1 : 0; + attr->fast_palette = (speed >= 7); + attr->use_dither_map = (speed <= (omp_get_max_threads () > 1 ? 7 : 5)); // parallelized dither map might speed up floyd remapping + attr->use_contrast_maps = (speed <= 7) || attr->use_dither_map; + attr->speed = speed; + return LIQ_OK; +} + +LIQ_EXPORT int +liq_get_speed (const liq_attr * attr) +{ + if (!CHECK_STRUCT_TYPE (attr, liq_attr)) + return -1; + + return attr->speed; +} + +LIQ_EXPORT liq_error +liq_set_output_gamma (liq_result * res, double gamma) +{ + if (!CHECK_STRUCT_TYPE (res, liq_result)) + return LIQ_INVALID_POINTER; + if (gamma <= 0 || gamma >= 1.0) + return LIQ_VALUE_OUT_OF_RANGE; + + if (res->remapping) { + liq_remapping_result_destroy (res->remapping); + res->remapping = NULL; + } + + res->gamma = gamma; + return LIQ_OK; +} + +LIQ_EXPORT liq_error +liq_set_min_opacity (liq_attr * attr, int min) +{ + if (!CHECK_STRUCT_TYPE (attr, liq_attr)) + return LIQ_INVALID_POINTER; + if (min < 0 || min > 255) + return LIQ_VALUE_OUT_OF_RANGE; + + attr->min_opaque_val = (double) min / 255.0; + return LIQ_OK; +} + +LIQ_EXPORT int +liq_get_min_opacity (const liq_attr * attr) +{ + if (!CHECK_STRUCT_TYPE (attr, liq_attr)) + return -1; + + return MIN (255, 256.0 * attr->min_opaque_val); +} + +LIQ_EXPORT void +liq_set_last_index_transparent (liq_attr * attr, int is_last) +{ + if (!CHECK_STRUCT_TYPE (attr, liq_attr)) + return; + + attr->last_index_transparent = ! !is_last; +} + +LIQ_EXPORT void +liq_set_log_callback (liq_attr * attr, liq_log_callback_function * callback, + void *user_info) +{ + if (!CHECK_STRUCT_TYPE (attr, liq_attr)) + return; + + liq_verbose_printf_flush (attr); + attr->log_callback = callback; + attr->log_callback_user_info = user_info; +} + +LIQ_EXPORT void +liq_set_log_flush_callback (liq_attr * attr, + liq_log_flush_callback_function * callback, void *user_info) +{ + if (!CHECK_STRUCT_TYPE (attr, liq_attr)) + return; + + attr->log_flush_callback = callback; + attr->log_flush_callback_user_info = user_info; +} + +LIQ_EXPORT liq_attr * +liq_attr_create (void) +{ + return liq_attr_create_with_allocator (NULL, NULL); +} + +LIQ_EXPORT void +liq_attr_destroy (liq_attr * attr) +{ + if (!CHECK_STRUCT_TYPE (attr, liq_attr)) { + return; + } + + liq_verbose_printf_flush (attr); + + attr->magic_header = liq_freed_magic; + attr->free (attr); +} + +LIQ_EXPORT liq_attr * +liq_attr_copy (liq_attr * orig) +{ + liq_attr *attr; + if (!CHECK_STRUCT_TYPE (orig, liq_attr)) { + return NULL; + } + + attr = orig->malloc (sizeof (liq_attr)); + if (!attr) + return NULL; + *attr = *orig; + return attr; +} + +static void * +liq_aligned_malloc (size_t size) +{ + unsigned char *ptr = malloc (size + 16); + uintptr_t offset; + if (!ptr) { + return NULL; + } + + offset = 16 - ((uintptr_t) ptr & 15); // also reserves 1 byte for ptr[-1] + ptr += offset; + assert (0 == (((uintptr_t) ptr) & 15)); + ptr[-1] = offset ^ 0x59; // store how much pointer was shifted to get the original for free() + return ptr; +} + +static void +liq_aligned_free (void *inptr) +{ + unsigned char *ptr = inptr; + size_t offset = ptr[-1] ^ 0x59; + assert (offset > 0 && offset <= 16); + free (ptr - offset); +} + +LIQ_EXPORT liq_attr * +liq_attr_create_with_allocator (void *(*custom_malloc) (size_t), + void (*custom_free) (void *)) +{ + liq_attr *attr; +#if USE_SSE + if (!is_sse_available ()) { + return NULL; + } +#endif + if (!custom_malloc && !custom_free) { + custom_malloc = liq_aligned_malloc; + custom_free = liq_aligned_free; + } else if (!custom_malloc != !custom_free) { + return NULL; // either specify both or none + } + + attr = custom_malloc (sizeof (liq_attr)); + if (!attr) + return NULL; + *attr = (liq_attr) { + .magic_header = liq_attr_magic,.malloc = custom_malloc,.free = custom_free,.max_colors = 256,.min_opaque_val = 1, // whether preserve opaque colors for IE (1.0=no, does not affect alpha) + .last_index_transparent = false, // puts transparent color at last index. This is workaround for blu-ray subtitles. + .target_mse = 0,.max_mse = MAX_DIFF,}; + liq_set_speed (attr, 3); + return attr; +} + +LIQ_EXPORT liq_error +liq_image_add_fixed_color (liq_image * img, liq_color color) +{ + float gamma_lut[256]; + rgba_pixel pix = (rgba_pixel) { + .r = color.r, + .g = color.g, + .b = color.b, + .a = color.a + }; + + if (!CHECK_STRUCT_TYPE (img, liq_image)) + return LIQ_INVALID_POINTER; + if (img->fixed_colors_count > 255) + return LIQ_BUFFER_TOO_SMALL; + + to_f_set_gamma (gamma_lut, img->gamma); + img->fixed_colors[img->fixed_colors_count++] = to_f (gamma_lut, pix); + return LIQ_OK; +} + +static bool +liq_image_use_low_memory (liq_image * img) +{ + img->temp_f_row = + img->malloc (sizeof (img->f_pixels[0]) * img->width * + omp_get_max_threads ()); + return img->temp_f_row != NULL; +} + +static bool +liq_image_should_use_low_memory (liq_image * img, const bool low_memory_hint) +{ + return img->width * img->height > (low_memory_hint ? LIQ_HIGH_MEMORY_LIMIT / 8 : LIQ_HIGH_MEMORY_LIMIT) / sizeof (f_pixel); // Watch out for integer overflow +} + +static liq_image * +liq_image_create_internal (liq_attr * attr, rgba_pixel * rows[], + liq_image_get_rgba_row_callback * row_callback, + void *row_callback_user_info, int width, int height, double gamma) +{ + liq_image *img; + if (gamma < 0 || gamma > 1.0) { + liq_log_error (attr, "gamma must be >= 0 and <= 1 (try 1/gamma instead)"); + return NULL; + } + + if (!rows && !row_callback) { + liq_log_error (attr, "missing row data"); + return NULL; + } + + img = attr->malloc (sizeof (liq_image)); + if (!img) + return NULL; + *img = (liq_image) { + .magic_header = liq_image_magic,.malloc = attr->malloc,.free = + attr->free,.width = width,.height = height,.gamma = + gamma ? gamma : 0.45455,.rows = rows,.row_callback = + row_callback,.row_callback_user_info = + row_callback_user_info,.min_opaque_val = attr->min_opaque_val,}; + + if (!rows || attr->min_opaque_val < 1.f) { + img->temp_row = + attr->malloc (sizeof (img->temp_row[0]) * width * + omp_get_max_threads ()); + if (!img->temp_row) + return NULL; + } + // if image is huge or converted pixels are not likely to be reused then don't cache converted pixels + if (liq_image_should_use_low_memory (img, !img->temp_row + && !attr->use_contrast_maps && !attr->use_dither_map)) { + verbose_print (attr, " conserving memory"); + if (!liq_image_use_low_memory (img)) + return NULL; + } + + if (img->min_opaque_val < 1.f) { + verbose_print (attr, + " Working around IE6 bug by making image less transparent..."); + } + + return img; +} + +LIQ_EXPORT liq_error +liq_image_set_memory_ownership (liq_image * img, int ownership_flags) +{ + if (!CHECK_STRUCT_TYPE (img, liq_image)) + return LIQ_INVALID_POINTER; + if (!img->rows || !ownership_flags + || (ownership_flags & ~(LIQ_OWN_ROWS | LIQ_OWN_PIXELS))) { + return LIQ_VALUE_OUT_OF_RANGE; + } + + if (ownership_flags & LIQ_OWN_ROWS) { + if (img->free_rows_internal) + return LIQ_VALUE_OUT_OF_RANGE; + img->free_rows = true; + } + + if (ownership_flags & LIQ_OWN_PIXELS) { + img->free_pixels = true; + if (!img->pixels) { + // for simplicity of this API there's no explicit bitmap argument, + // so the row with the lowest address is assumed to be at the start of the bitmap + img->pixels = img->rows[0]; + for (unsigned int i = 1; i < img->height; i++) { + img->pixels = MIN (img->pixels, img->rows[i]); + } + } + } + + return LIQ_OK; +} + +static bool +check_image_size (const liq_attr * attr, const int width, const int height) +{ + if (!CHECK_STRUCT_TYPE (attr, liq_attr)) { + return false; + } + + if (width <= 0 || height <= 0) { + liq_log_error (attr, "width and height must be > 0"); + return false; + } + if (width > INT_MAX / height) { + liq_log_error (attr, "image too large"); + return false; + } + return true; +} + +LIQ_EXPORT liq_image * +liq_image_create_custom (liq_attr * attr, + liq_image_get_rgba_row_callback * row_callback, void *user_info, int width, + int height, double gamma) +{ + if (!check_image_size (attr, width, height)) { + return NULL; + } + return liq_image_create_internal (attr, NULL, row_callback, user_info, width, + height, gamma); +} + +LIQ_EXPORT liq_image * +liq_image_create_rgba_rows (liq_attr * attr, void *rows[], int width, + int height, double gamma) +{ + if (!check_image_size (attr, width, height)) { + return NULL; + } + + for (int i = 0; i < height; i++) { + if (!CHECK_USER_POINTER (rows + i) || !CHECK_USER_POINTER (rows[i])) { + liq_log_error (attr, "invalid row pointers"); + return NULL; + } + } + return liq_image_create_internal (attr, (rgba_pixel **) rows, NULL, NULL, + width, height, gamma); +} + +LIQ_EXPORT liq_image * +liq_image_create_rgba (liq_attr * attr, void *bitmap, int width, int height, + double gamma) +{ + rgba_pixel *pixels; + rgba_pixel **rows; + liq_image *image; + + if (!check_image_size (attr, width, height)) { + return NULL; + } + if (!CHECK_USER_POINTER (bitmap)) { + liq_log_error (attr, "invalid bitmap pointer"); + return NULL; + } + + pixels = bitmap; + rows = attr->malloc (sizeof (rows[0]) * height); + if (!rows) + return NULL; + + for (int i = 0; i < height; i++) { + rows[i] = pixels + width * i; + } + + image = + liq_image_create_internal (attr, rows, NULL, NULL, width, height, gamma); + image->free_rows = true; + image->free_rows_internal = true; + return image; +} + +NEVER_INLINE LIQ_EXPORT void +liq_executing_user_callback (liq_image_get_rgba_row_callback * callback, + liq_color * temp_row, int row, int width, void *user_info); +LIQ_EXPORT void +liq_executing_user_callback (liq_image_get_rgba_row_callback * callback, + liq_color * temp_row, int row, int width, void *user_info) +{ + assert (callback); + assert (temp_row); + callback (temp_row, row, width, user_info); +} + +inline static bool +liq_image_can_use_rows (liq_image * img) +{ + const bool iebug = img->min_opaque_val < 1.f; + return (img->rows && !iebug); +} + +static const rgba_pixel * +liq_image_get_row_rgba (liq_image * img, unsigned int row) +{ + rgba_pixel *temp_row; + if (liq_image_can_use_rows (img)) { + return img->rows[row]; + } + + assert (img->temp_row); + temp_row = img->temp_row + img->width * omp_get_thread_num (); + if (img->rows) { + memcpy (temp_row, img->rows[row], img->width * sizeof (temp_row[0])); + } else { + liq_executing_user_callback (img->row_callback, (liq_color *) temp_row, row, + img->width, img->row_callback_user_info); + } + + if (img->min_opaque_val < 1.f) + modify_alpha (img, temp_row); + return temp_row; +} + +static void +convert_row_to_f (liq_image * img, f_pixel * row_f_pixels, + const unsigned int row, const float gamma_lut[]) +{ + assert (row_f_pixels); + assert (!USE_SSE || 0 == ((uintptr_t) row_f_pixels & 15)); + + { + const rgba_pixel *const row_pixels = liq_image_get_row_rgba (img, row); + unsigned int col; + + for (col = 0; col < img->width; col++) { + row_f_pixels[col] = to_f (gamma_lut, row_pixels[col]); + } + } +} + +static const f_pixel * +liq_image_get_row_f (liq_image * img, unsigned int row) +{ + if (!img->f_pixels) { + if (img->temp_f_row) { + float gamma_lut[256]; + f_pixel *row_for_thread; + + to_f_set_gamma (gamma_lut, img->gamma); + row_for_thread = img->temp_f_row + img->width * omp_get_thread_num (); + convert_row_to_f (img, row_for_thread, row, gamma_lut); + + return row_for_thread; + } + + assert (omp_get_thread_num () == 0); + if (!liq_image_should_use_low_memory (img, false)) { + img->f_pixels = + img->malloc (sizeof (img->f_pixels[0]) * img->width * img->height); + } + if (!img->f_pixels) { + if (!liq_image_use_low_memory (img)) + return NULL; + return liq_image_get_row_f (img, row); + } + + { + float gamma_lut[256]; + to_f_set_gamma (gamma_lut, img->gamma); + for (unsigned int i = 0; i < img->height; i++) { + convert_row_to_f (img, &img->f_pixels[i * img->width], i, gamma_lut); + } + } + } + return img->f_pixels + img->width * row; +} + +LIQ_EXPORT int +liq_image_get_width (const liq_image * input_image) +{ + if (!CHECK_STRUCT_TYPE (input_image, liq_image)) + return -1; + return input_image->width; +} + +LIQ_EXPORT int +liq_image_get_height (const liq_image * input_image) +{ + if (!CHECK_STRUCT_TYPE (input_image, liq_image)) + return -1; + return input_image->height; +} + +typedef void free_func (void *); + +static free_func * +get_default_free_func (liq_image * img) +{ + // When default allocator is used then user-supplied pointers must be freed with free() + if (img->free_rows_internal || img->free != liq_aligned_free) { + return img->free; + } + return free; +} + +static void +liq_image_free_rgba_source (liq_image * input_image) +{ + if (input_image->free_pixels && input_image->pixels) { + get_default_free_func (input_image) (input_image->pixels); + input_image->pixels = NULL; + } + + if (input_image->free_rows && input_image->rows) { + get_default_free_func (input_image) (input_image->rows); + input_image->rows = NULL; + } +} + +LIQ_EXPORT void +liq_image_destroy (liq_image * input_image) +{ + if (!CHECK_STRUCT_TYPE (input_image, liq_image)) + return; + + liq_image_free_rgba_source (input_image); + + if (input_image->noise) { + input_image->free (input_image->noise); + } + + if (input_image->edges) { + input_image->free (input_image->edges); + } + + if (input_image->dither_map) { + input_image->free (input_image->dither_map); + } + + if (input_image->f_pixels) { + input_image->free (input_image->f_pixels); + } + + if (input_image->temp_row) { + input_image->free (input_image->temp_row); + } + + if (input_image->temp_f_row) { + input_image->free (input_image->temp_f_row); + } + + input_image->magic_header = liq_freed_magic; + input_image->free (input_image); +} + +LIQ_EXPORT liq_result * +liq_quantize_image (liq_attr * attr, liq_image * img) +{ + histogram *hist; + liq_result *result; + + if (!CHECK_STRUCT_TYPE (attr, liq_attr)) + return NULL; + if (!CHECK_STRUCT_TYPE (img, liq_image)) { + liq_log_error (attr, "invalid image pointer"); + return NULL; + } + + hist = get_histogram (img, attr); + if (!hist) { + return NULL; + } + + result = pngquant_quantize (hist, attr, img); + + pam_freeacolorhist (hist); + return result; +} + +LIQ_EXPORT liq_error +liq_set_dithering_level (liq_result * res, float dither_level) +{ + if (!CHECK_STRUCT_TYPE (res, liq_result)) + return LIQ_INVALID_POINTER; + + if (res->remapping) { + liq_remapping_result_destroy (res->remapping); + res->remapping = NULL; + } + + if (res->dither_level < 0 || res->dither_level > 1.0f) + return LIQ_VALUE_OUT_OF_RANGE; + res->dither_level = dither_level; + return LIQ_OK; +} + +static liq_remapping_result * +liq_remapping_result_create (liq_result * result) +{ + liq_remapping_result *res; + + if (!CHECK_STRUCT_TYPE (result, liq_result)) { + return NULL; + } + + res = result->malloc (sizeof (liq_remapping_result)); + if (!res) + return NULL; + *res = (liq_remapping_result) { + .magic_header = liq_remapping_result_magic,.malloc = result->malloc,.free = + result->free,.dither_level = result->dither_level,.use_dither_map = + result->use_dither_map,.palette_error = result->palette_error,.gamma = + result->gamma,.palette = pam_duplicate_colormap (result->palette),}; + return res; +} + +LIQ_EXPORT double +liq_get_output_gamma (const liq_result * result) +{ + if (!CHECK_STRUCT_TYPE (result, liq_result)) + return -1; + + return result->gamma; +} + +static void +liq_remapping_result_destroy (liq_remapping_result * result) +{ + if (!CHECK_STRUCT_TYPE (result, liq_remapping_result)) + return; + + if (result->palette) + pam_freecolormap (result->palette); + if (result->pixels) + result->free (result->pixels); + + result->magic_header = liq_freed_magic; + result->free (result); +} + +LIQ_EXPORT void +liq_result_destroy (liq_result * res) +{ + if (!CHECK_STRUCT_TYPE (res, liq_result)) + return; + + memset (&res->int_palette, 0, sizeof (liq_palette)); + + if (res->remapping) { + memset (&res->remapping->int_palette, 0, sizeof (liq_palette)); + liq_remapping_result_destroy (res->remapping); + } + + pam_freecolormap (res->palette); + + res->magic_header = liq_freed_magic; + res->free (res); +} + +LIQ_EXPORT double +liq_get_quantization_error (liq_result * result) +{ + if (!CHECK_STRUCT_TYPE (result, liq_result)) + return -1; + + if (result->palette_error >= 0) { + return result->palette_error * 65536.0 / 6.0; + } + + if (result->remapping && result->remapping->palette_error >= 0) { + return result->remapping->palette_error * 65536.0 / 6.0; + } + + return result->palette_error; +} + +LIQ_EXPORT int +liq_get_quantization_quality (liq_result * result) +{ + if (!CHECK_STRUCT_TYPE (result, liq_result)) + return -1; + + if (result->palette_error >= 0) { + return mse_to_quality (result->palette_error); + } + + if (result->remapping && result->remapping->palette_error >= 0) { + return mse_to_quality (result->remapping->palette_error); + } + + return result->palette_error; +} + +static int +compare_popularity (const void *ch1, const void *ch2) +{ + const float v1 = ((const colormap_item *) ch1)->popularity; + const float v2 = ((const colormap_item *) ch2)->popularity; + return v1 > v2 ? -1 : 1; +} + +static void +sort_palette_qsort (colormap * map, int start, int nelem) +{ + qsort (map->palette + start, nelem, sizeof (map->palette[0]), + compare_popularity); +} + +#define SWAP_PALETTE(map, a,b) { \ + const colormap_item tmp = (map)->palette[(a)]; \ + (map)->palette[(a)] = (map)->palette[(b)]; \ + (map)->palette[(b)] = tmp; } + +static void +sort_palette (colormap * map, const liq_attr * options) +{ + unsigned int i; + unsigned int num_transparent; + + /* + ** Step 3.5 [GRR]: remap the palette colors so that all entries with + ** the maximal alpha value (i.e., fully opaque) are at the end and can + ** therefore be omitted from the tRNS chunk. + */ + if (options->last_index_transparent) { + for (i = 0; i < map->colors; i++) { + if (map->palette[i].acolor.a < 1.0 / 256.0) { + const unsigned int old = i, transparent_dest = map->colors - 1; + + SWAP_PALETTE (map, transparent_dest, old); + + /* colors sorted by popularity make pngs slightly more compressible */ + sort_palette_qsort (map, 0, map->colors - 1); + return; + } + } + } + /* move transparent colors to the beginning to shrink trns chunk */ + num_transparent = 0; + for (i = 0; i < map->colors; i++) { + if (map->palette[i].acolor.a < 255.0 / 256.0) { + // current transparent color is swapped with earlier opaque one + if (i != num_transparent) { + SWAP_PALETTE (map, num_transparent, i); + i--; + } + num_transparent++; + } + } + + liq_verbose_printf (options, + " eliminated opaque tRNS-chunk entries...%d entr%s transparent", + num_transparent, (num_transparent == 1) ? "y" : "ies"); + + /* colors sorted by popularity make pngs slightly more compressible + * opaque and transparent are sorted separately + */ + sort_palette_qsort (map, 0, num_transparent); + sort_palette_qsort (map, num_transparent, map->colors - num_transparent); + + if (map->colors > 16) { + SWAP_PALETTE (map, 7, 1); // slightly improves compression + SWAP_PALETTE (map, 8, 2); + SWAP_PALETTE (map, 9, 3); + } +} + +inline static unsigned int +posterize_channel (unsigned int color, unsigned int bits) +{ + return (color & ~((1 << bits) - 1)) | (color >> (8 - bits)); +} + +static void +set_rounded_palette (liq_palette * const dest, colormap * const map, + const double gamma, unsigned int posterize) +{ + float gamma_lut[256]; + to_f_set_gamma (gamma_lut, gamma); + + dest->count = map->colors; + for (unsigned int x = 0; x < map->colors; ++x) { + rgba_pixel px = to_rgb (gamma, map->palette[x].acolor); + + px.r = posterize_channel (px.r, posterize); + px.g = posterize_channel (px.g, posterize); + px.b = posterize_channel (px.b, posterize); + px.a = posterize_channel (px.a, posterize); + + map->palette[x].acolor = to_f (gamma_lut, px); /* saves rounding error introduced by to_rgb, which makes remapping & dithering more accurate */ + + if (!px.a) { + px.r = 'L'; + px.g = 'i'; + px.b = 'q'; + } + + dest->entries[x] = (liq_color) { + .r = px.r,.g = px.g,.b = px.b,.a = px.a}; + } +} + +LIQ_EXPORT const liq_palette * +liq_get_palette (liq_result * result) +{ + if (!CHECK_STRUCT_TYPE (result, liq_result)) + return NULL; + + if (result->remapping && result->remapping->int_palette.count) { + return &result->remapping->int_palette; + } + + if (!result->int_palette.count) { + set_rounded_palette (&result->int_palette, result->palette, result->gamma, + result->min_posterization_output); + } + return &result->int_palette; +} + +#define MAX_THREADS 8 + +static float +remap_to_palette (liq_image * const input_image, + unsigned char *const *const output_pixels, colormap * const map, + const bool fast) +{ + const int rows = input_image->height; + const unsigned int cols = input_image->width; + const float min_opaque_val = input_image->min_opaque_val; + double remapping_error = 0; + + if (!liq_image_get_row_f (input_image, 0)) { // trigger lazy conversion + return -1; + } + + { + struct nearest_map *const n = nearest_init (map, fast); + + const unsigned int max_threads = MIN (MAX_THREADS, omp_get_max_threads ()); + viter_state *average_color = + g_alloca (sizeof (viter_state) * (VITER_CACHE_LINE_GAP + + map->colors) * MAX_THREADS); + unsigned int row, col; + + viter_init (map, max_threads, average_color); + +#pragma omp parallel for if (rows*cols > 3000) \ + schedule(static) default(none) shared(average_color) reduction(+:remapping_error) + for (row = 0; row < rows; ++row) { + const f_pixel *const row_pixels = liq_image_get_row_f (input_image, row); + unsigned int last_match = 0; + for (col = 0; col < cols; ++col) { + f_pixel px = row_pixels[col]; + float diff; + + output_pixels[row][col] = last_match = + nearest_search (n, px, last_match, min_opaque_val, &diff); + + remapping_error += diff; + viter_update_color (px, 1.0, map, last_match, omp_get_thread_num (), + average_color); + } + } + + viter_finalize (map, max_threads, average_color); + + nearest_free (n); + } + + return remapping_error / (input_image->width * input_image->height); +} + +inline static f_pixel +get_dithered_pixel (const float dither_level, const float max_dither_error, + const f_pixel thiserr, const f_pixel px) +{ + /* Use Floyd-Steinberg errors to adjust actual color. */ + const float sr = thiserr.r * dither_level, + sg = thiserr.g * dither_level, + sb = thiserr.b * dither_level, sa = thiserr.a * dither_level; + float a; + float ratio = 1.0; + float dither_error; + + // allowing some overflow prevents undithered bands caused by clamping of all channels + if (px.r + sr > 1.03) + ratio = MIN (ratio, (1.03 - px.r) / sr); + else if (px.r + sr < 0) + ratio = MIN (ratio, px.r / -sr); + if (px.g + sg > 1.03) + ratio = MIN (ratio, (1.03 - px.g) / sg); + else if (px.g + sg < 0) + ratio = MIN (ratio, px.g / -sg); + if (px.b + sb > 1.03) + ratio = MIN (ratio, (1.03 - px.b) / sb); + else if (px.b + sb < 0) + ratio = MIN (ratio, px.b / -sb); + + a = px.a + sa; + if (a > 1.0) { + a = 1.0; + } else if (a < 0) { + a = 0; + } + // If dithering error is crazy high, don't propagate it that much + // This prevents crazy geen pixels popping out of the blue (or red or black! ;) + dither_error = sr * sr + sg * sg + sb * sb + sa * sa; + if (dither_error > max_dither_error) { + ratio *= 0.8; + } else if (dither_error < 2.f / 256.f / 256.f) { + // don't dither areas that don't have noticeable error — makes file smaller + return px; + } + + return (f_pixel) { + .r = px.r + sr * ratio,.g = px.g + sg * ratio,.b = px.b + sb * ratio,.a = a,}; +} + +/** + Uses edge/noise map to apply dithering only to flat areas. Dithering on edges creates jagged lines, and noisy areas are "naturally" dithered. + + If output_image_is_remapped is true, only pixels noticeably changed by error diffusion will be written to output image. + */ +static void +remap_to_palette_floyd (liq_image * input_image, + unsigned char *const output_pixels[], const colormap * map, + const float max_dither_error, const bool use_dither_map, + const bool output_image_is_remapped, float base_dithering_level) +{ + const unsigned int rows = input_image->height, cols = input_image->width; + const unsigned char *dither_map = + use_dither_map ? (input_image-> + dither_map ? input_image->dither_map : input_image->edges) : NULL; + const float min_opaque_val = input_image->min_opaque_val; + + const colormap_item *acolormap = map->palette; + + struct nearest_map *const n = nearest_init (map, false); + unsigned int col; + + /* Initialize Floyd-Steinberg error vectors. */ + f_pixel *restrict thiserr, *restrict nexterr; + thiserr = input_image->malloc ((cols + 2) * sizeof (*thiserr) * 2); // +2 saves from checking out of bounds access + nexterr = thiserr + (cols + 2); + srand (12345); /* deterministic dithering is better for comparing results */ + if (!thiserr) + return; + + for (col = 0; col < cols + 2; ++col) { + const double rand_max = RAND_MAX; + thiserr[col].r = ((double) rand () - rand_max / 2.0) / rand_max / 255.0; + thiserr[col].g = ((double) rand () - rand_max / 2.0) / rand_max / 255.0; + thiserr[col].b = ((double) rand () - rand_max / 2.0) / rand_max / 255.0; + thiserr[col].a = ((double) rand () - rand_max / 2.0) / rand_max / 255.0; + } + + // response to this value is non-linear and without it any value < 0.8 would give almost no dithering + base_dithering_level = + 1.0 - (1.0 - base_dithering_level) * (1.0 - base_dithering_level) * (1.0 - + base_dithering_level); + + if (dither_map) { + base_dithering_level *= 1.0 / 255.0; // convert byte to float + } + base_dithering_level *= 15.0 / 16.0; // prevent small errors from accumulating + + { + bool fs_direction = true; + unsigned int last_match = 0; + for (unsigned int row = 0; row < rows; ++row) { + unsigned int col = (fs_direction) ? 0 : (cols - 1); + const f_pixel *const row_pixels = liq_image_get_row_f (input_image, row); + + memset (nexterr, 0, (cols + 2) * sizeof (*nexterr)); + + do { + float dither_level = base_dithering_level; + f_pixel spx, xp, err; + unsigned int guessed_match; + + if (dither_map) { + dither_level *= dither_map[row * cols + col]; + } + + spx = + get_dithered_pixel (dither_level, max_dither_error, + thiserr[col + 1], row_pixels[col]); + + guessed_match = + output_image_is_remapped ? output_pixels[row][col] : last_match; + output_pixels[row][col] = last_match = + nearest_search (n, spx, guessed_match, min_opaque_val, NULL); + + xp = acolormap[last_match].acolor; + err.r = spx.r - xp.r; + err.g = spx.r - xp.g; + err.b = spx.r - xp.b; + err.a = spx.r - xp.a; + + // If dithering error is crazy high, don't propagate it that much + // This prevents crazy geen pixels popping out of the blue (or red or black! ;) + if (err.r * err.r + err.g * err.g + err.b * err.b + err.a * err.a > + max_dither_error) { + dither_level *= 0.75; + } + + { + const float colorimp = + (3.0f + acolormap[last_match].acolor.a) / 4.0f * dither_level; + err.r *= colorimp; + err.g *= colorimp; + err.b *= colorimp; + err.a *= dither_level; + } + + /* Propagate Floyd-Steinberg error terms. */ + if (fs_direction) { + thiserr[col + 2].a += err.a * (7.f / 16.f); + thiserr[col + 2].r += err.r * (7.f / 16.f); + thiserr[col + 2].g += err.g * (7.f / 16.f); + thiserr[col + 2].b += err.b * (7.f / 16.f); + + nexterr[col + 2].a = err.a * (1.f / 16.f); + nexterr[col + 2].r = err.r * (1.f / 16.f); + nexterr[col + 2].g = err.g * (1.f / 16.f); + nexterr[col + 2].b = err.b * (1.f / 16.f); + + nexterr[col + 1].a += err.a * (5.f / 16.f); + nexterr[col + 1].r += err.r * (5.f / 16.f); + nexterr[col + 1].g += err.g * (5.f / 16.f); + nexterr[col + 1].b += err.b * (5.f / 16.f); + + nexterr[col].a += err.a * (3.f / 16.f); + nexterr[col].r += err.r * (3.f / 16.f); + nexterr[col].g += err.g * (3.f / 16.f); + nexterr[col].b += err.b * (3.f / 16.f); + + } else { + thiserr[col].a += err.a * (7.f / 16.f); + thiserr[col].r += err.r * (7.f / 16.f); + thiserr[col].g += err.g * (7.f / 16.f); + thiserr[col].b += err.b * (7.f / 16.f); + + nexterr[col].a = err.a * (1.f / 16.f); + nexterr[col].r = err.r * (1.f / 16.f); + nexterr[col].g = err.g * (1.f / 16.f); + nexterr[col].b = err.b * (1.f / 16.f); + + nexterr[col + 1].a += err.a * (5.f / 16.f); + nexterr[col + 1].r += err.r * (5.f / 16.f); + nexterr[col + 1].g += err.g * (5.f / 16.f); + nexterr[col + 1].b += err.b * (5.f / 16.f); + + nexterr[col + 2].a += err.a * (3.f / 16.f); + nexterr[col + 2].r += err.r * (3.f / 16.f); + nexterr[col + 2].g += err.g * (3.f / 16.f); + nexterr[col + 2].b += err.b * (3.f / 16.f); + } + + // remapping is done in zig-zag + if (fs_direction) { + ++col; + if (col >= cols) + break; + } else { + if (col <= 0) + break; + --col; + } + } while (1); + + { + f_pixel *const temperr = thiserr; + thiserr = nexterr; + nexterr = temperr; + } + + fs_direction = !fs_direction; + } + } + + input_image->free (MIN (thiserr, nexterr)); // MIN because pointers were swapped + nearest_free (n); +} + +/* fixed colors are always included in the palette, so it would be wasteful to duplicate them in palette from histogram */ +static void +remove_fixed_colors_from_histogram (histogram * hist, + const liq_image * input_image, const float target_mse) +{ + const float max_difference = MAX (target_mse / 2.0, 2.0 / 256.0 / 256.0); + if (input_image->fixed_colors_count) { + for (int j = 0; j < hist->size; j++) { + for (unsigned int i = 0; i < input_image->fixed_colors_count; i++) { + if (colordifference (hist->achv[j].acolor, + input_image->fixed_colors[i]) < max_difference) { + hist->achv[j] = hist->achv[--hist->size]; // remove color from histogram by overwriting with the last entry + j--; + break; // continue searching histogram + } + } + } + } +} + +/* histogram contains information how many times each color is present in the image, weighted by importance_map */ +static histogram * +get_histogram (liq_image * input_image, const liq_attr * options) +{ + unsigned int ignorebits = + MAX (options->min_posterization_output, options->min_posterization_input); + const unsigned int cols = input_image->width, rows = input_image->height; + + if (!input_image->noise && options->use_contrast_maps) { + contrast_maps (input_image); + } + + /* + ** Step 2: attempt to make a histogram of the colors, unclustered. + ** If at first we don't succeed, increase ignorebits to increase color + ** coherence and try again. + */ + + { + unsigned int maxcolors = options->max_histogram_entries; + + struct acolorhash_table *acht; + const bool all_rows_at_once = liq_image_can_use_rows (input_image); + histogram *hist; + + do { + acht = + pam_allocacolorhash (maxcolors, rows * cols, ignorebits, + options->malloc, options->free); + if (!acht) + return NULL; + + // histogram uses noise contrast map for importance. Color accuracy in noisy areas is not very important. + // noise map does not include edges to avoid ruining anti-aliasing + for (unsigned int row = 0; row < rows; row++) { + bool added_ok; + if (all_rows_at_once) { + added_ok = + pam_computeacolorhash (acht, + (const rgba_pixel * const *) input_image->rows, cols, rows, + input_image->noise); + if (added_ok) + break; + } else { + const rgba_pixel *rows_p[1] = + { liq_image_get_row_rgba (input_image, row) }; + added_ok = + pam_computeacolorhash (acht, rows_p, cols, 1, + input_image->noise ? &input_image->noise[row * cols] : NULL); + } + if (!added_ok) { + ignorebits++; + liq_verbose_printf (options, + " too many colors! Scaling colors to improve clustering... %d", + ignorebits); + pam_freeacolorhash (acht); + acht = NULL; + break; + } + } + } while (!acht); + + if (input_image->noise) { + input_image->free (input_image->noise); + input_image->noise = NULL; + } + + if (input_image->free_pixels && input_image->f_pixels) { + liq_image_free_rgba_source (input_image); // bow can free the RGBA source if copy has been made in f_pixels + } + + hist = + pam_acolorhashtoacolorhist (acht, input_image->gamma, options->malloc, + options->free); + pam_freeacolorhash (acht); + if (hist) { + liq_verbose_printf (options, " made histogram...%d colors found", + hist->size); + remove_fixed_colors_from_histogram (hist, input_image, + options->target_mse); + } + + return hist; + } +} + +static void +modify_alpha (liq_image * input_image, rgba_pixel * const row_pixels) +{ + /* IE6 makes colors with even slightest transparency completely transparent, + thus to improve situation in IE, make colors that are less than ~10% transparent + completely opaque */ + + const float min_opaque_val = input_image->min_opaque_val; + const float almost_opaque_val = min_opaque_val * 169.f / 256.f; + const unsigned int almost_opaque_val_int = + (min_opaque_val * 169.f / 256.f) * 255.f; + + for (unsigned int col = 0; col < input_image->width; col++) { + const rgba_pixel px = row_pixels[col]; + + /* ie bug: to avoid visible step caused by forced opaqueness, linearily raise opaqueness of almost-opaque colors */ + if (px.a >= almost_opaque_val_int) { + float al = px.a / 255.f; + al = almost_opaque_val + (al - almost_opaque_val) * (1.f - + almost_opaque_val) / (min_opaque_val - almost_opaque_val); + al *= 256.f; + row_pixels[col].a = al >= 255.f ? 255 : al; + } + } +} + +/** + Builds two maps: + noise - approximation of areas with high-frequency noise, except straight edges. 1=flat, 0=noisy. + edges - noise map including all edges + */ +static void +contrast_maps (liq_image * image) +{ + const int cols = image->width, rows = image->height; + unsigned char *restrict noise, *restrict edges, *restrict tmp; + const f_pixel *curr_row, *prev_row, *next_row; + int i, j; + + if (cols < 4 || rows < 4 || (3 * cols * rows) > LIQ_HIGH_MEMORY_LIMIT) { + return; + } + + noise = image->malloc (cols * rows); + edges = image->malloc (cols * rows); + tmp = image->malloc (cols * rows); + + if (!noise || !edges || !tmp) { + return; + } + + curr_row = prev_row = next_row = liq_image_get_row_f (image, 0); + + for (j = 0; j < rows; j++) { + f_pixel prev, curr, next; + + prev_row = curr_row; + curr_row = next_row; + next_row = liq_image_get_row_f (image, MIN (rows - 1, j + 1)); + + curr = curr_row[0]; + next = curr; + for (i = 0; i < cols; i++) { + prev = curr; + curr = next; + next = curr_row[MIN (cols - 1, i + 1)]; + + // contrast is difference between pixels neighbouring horizontally and vertically + { + const float a = fabsf (prev.a + next.a - curr.a * 2.f), + r = fabsf (prev.r + next.r - curr.r * 2.f), + g = fabsf (prev.g + next.g - curr.g * 2.f), + b = fabsf (prev.b + next.b - curr.b * 2.f); + + const f_pixel prevl = prev_row[i]; + const f_pixel nextl = next_row[i]; + + const float a1 = fabsf (prevl.a + nextl.a - curr.a * 2.f), + r1 = fabsf (prevl.r + nextl.r - curr.r * 2.f), + g1 = fabsf (prevl.g + nextl.g - curr.g * 2.f), + b1 = fabsf (prevl.b + nextl.b - curr.b * 2.f); + + const float horiz = MAX (MAX (a, r), MAX (g, b)); + const float vert = MAX (MAX (a1, r1), MAX (g1, b1)); + const float edge = MAX (horiz, vert); + float z = edge - fabsf (horiz - vert) * .5f; + z = 1.f - MAX (z, MIN (horiz, vert)); + z *= z; // noise is amplified + z *= z; + + z *= 256.f; + noise[j * cols + i] = z < 256 ? z : 255; + z = (1.f - edge) * 256.f; + edges[j * cols + i] = z < 256 ? z : 255; + } + } + } + + // noise areas are shrunk and then expanded to remove thin edges from the map + liq_max3 (noise, tmp, cols, rows); + liq_max3 (tmp, noise, cols, rows); + + liq_blur (noise, tmp, noise, cols, rows, 3); + + liq_max3 (noise, tmp, cols, rows); + + liq_min3 (tmp, noise, cols, rows); + liq_min3 (noise, tmp, cols, rows); + liq_min3 (tmp, noise, cols, rows); + + liq_min3 (edges, tmp, cols, rows); + liq_max3 (tmp, edges, cols, rows); + for (int i = 0; i < cols * rows; i++) + edges[i] = MIN (noise[i], edges[i]); + + image->free (tmp); + + image->noise = noise; + image->edges = edges; +} + +/** + * Builds map of neighbor pixels mapped to the same palette entry + * + * For efficiency/simplicity it mainly looks for same consecutive pixels horizontally + * and peeks 1 pixel above/below. Full 2d algorithm doesn't improve it significantly. + * Correct flood fill doesn't have visually good properties. + */ +static void +update_dither_map (unsigned char *const *const row_pointers, + liq_image * input_image) +{ + const unsigned int width = input_image->width; + const unsigned int height = input_image->height; + unsigned char *const edges = input_image->edges; + + for (unsigned int row = 0; row < height; row++) { + unsigned char lastpixel = row_pointers[row][0]; + unsigned int lastcol = 0; + + for (unsigned int col = 1; col < width; col++) { + const unsigned char px = row_pointers[row][col]; + + if (px != lastpixel || col == width - 1) { + float neighbor_count = 2.5f + col - lastcol; + + unsigned int i = lastcol; + while (i < col) { + if (row > 0) { + unsigned char pixelabove = row_pointers[row - 1][i]; + if (pixelabove == lastpixel) + neighbor_count += 1.f; + } + if (row < height - 1) { + unsigned char pixelbelow = row_pointers[row + 1][i]; + if (pixelbelow == lastpixel) + neighbor_count += 1.f; + } + i++; + } + + while (lastcol <= col) { + float e = edges[row * width + lastcol] / 255.f; + e *= 1.f - 2.5f / neighbor_count; + edges[row * width + lastcol++] = e * 255.f; + } + lastpixel = px; + } + } + } + input_image->dither_map = input_image->edges; + input_image->edges = NULL; +} + +static colormap * +add_fixed_colors_to_palette (colormap * palette, const int max_colors, + const f_pixel fixed_colors[], const int fixed_colors_count, + void *(*malloc) (size_t), void (*free) (void *)) +{ + colormap *newpal; + unsigned int i, palette_max; + int j; + + if (!fixed_colors_count) + return palette; + + newpal = + pam_colormap (MIN (max_colors, + (palette ? palette->colors : 0) + fixed_colors_count), malloc, free); + + i = 0; + if (palette && fixed_colors_count < max_colors) { + palette_max = MIN (palette->colors, max_colors - fixed_colors_count); + for (; i < palette_max; i++) { + newpal->palette[i] = palette->palette[i]; + } + } + for (j = 0; j < MIN (max_colors, fixed_colors_count); j++) { + newpal->palette[i++] = (colormap_item) { + .acolor = fixed_colors[j],.fixed = true,}; + } + if (palette) + pam_freecolormap (palette); + return newpal; +} + +static void +adjust_histogram_callback (hist_item * item, float diff) +{ + item->adjusted_weight = + (item->perceptual_weight + item->adjusted_weight) * (sqrtf (1.f + diff)); +} + +/** + Repeats mediancut with different histogram weights to find palette with minimum error. + + feedback_loop_trials controls how long the search will take. < 0 skips the iteration. + */ +static colormap * +find_best_palette (histogram * hist, const liq_attr * options, + const double max_mse, const f_pixel fixed_colors[], + const unsigned int fixed_colors_count, double *palette_error_p) +{ + unsigned int max_colors = options->max_colors; + + // if output is posterized it doesn't make sense to aim for perfrect colors, so increase target_mse + // at this point actual gamma is not set, so very conservative posterization estimate is used + const double target_mse = MIN (max_mse, MAX (options->target_mse, + pow ((1 << options->min_posterization_output) / 1024.0, 2))); + int feedback_loop_trials = options->feedback_loop_trials; + colormap *acolormap = NULL; + double least_error = MAX_DIFF; + double target_mse_overshoot = feedback_loop_trials > 0 ? 1.05 : 1.0; + const double percent = + (double) (feedback_loop_trials > 0 ? feedback_loop_trials : 1) / 100.0; + + do { + colormap *newmap; + double total_error; + + if (hist->size && fixed_colors_count < max_colors) { + newmap = + mediancut (hist, options->min_opaque_val, + max_colors - fixed_colors_count, target_mse * target_mse_overshoot, + MAX (MAX (90.0 / 65536.0, target_mse), least_error) * 1.2, + options->malloc, options->free); + } else { + feedback_loop_trials = 0; + newmap = NULL; + } + newmap = + add_fixed_colors_to_palette (newmap, max_colors, fixed_colors, + fixed_colors_count, options->malloc, options->free); + if (!newmap) { + return NULL; + } + + if (feedback_loop_trials <= 0) { + return newmap; + } + // after palette has been created, total error (MSE) is calculated to keep the best palette + // at the same time Voronoi iteration is done to improve the palette + // and histogram weights are adjusted based on remapping error to give more weight to poorly matched colors + + { + const bool first_run_of_target_mse = !acolormap && target_mse > 0; + total_error = + viter_do_iteration (hist, newmap, options->min_opaque_val, + first_run_of_target_mse ? NULL : adjust_histogram_callback, !acolormap + || options->fast_palette); + } + + // goal is to increase quality or to reduce number of colors used if quality is good enough + if (!acolormap || total_error < least_error || (total_error <= target_mse + && newmap->colors < max_colors)) { + if (acolormap) + pam_freecolormap (acolormap); + acolormap = newmap; + + if (total_error < target_mse && total_error > 0) { + // voronoi iteration improves quality above what mediancut aims for + // this compensates for it, making mediancut aim for worse + target_mse_overshoot = + MIN (target_mse_overshoot * 1.25, target_mse / total_error); + } + + least_error = total_error; + + // if number of colors could be reduced, try to keep it that way + // but allow extra color as a bit of wiggle room in case quality can be improved too + max_colors = MIN (newmap->colors + 1, max_colors); + + feedback_loop_trials -= 1; // asymptotic improvement could make it go on forever + } else { + for (unsigned int j = 0; j < hist->size; j++) { + hist->achv[j].adjusted_weight = + (hist->achv[j].perceptual_weight + + hist->achv[j].adjusted_weight) / 2.0; + } + + target_mse_overshoot = 1.0; + feedback_loop_trials -= 6; + // if error is really bad, it's unlikely to improve, so end sooner + if (total_error > least_error * 4) + feedback_loop_trials -= 3; + pam_freecolormap (newmap); + } + + liq_verbose_printf (options, " selecting colors...%d%%", 100 - MAX (0, + (int) (feedback_loop_trials / percent))); + } + while (feedback_loop_trials > 0); + + *palette_error_p = least_error; + return acolormap; +} + +static liq_result * +pngquant_quantize (histogram * hist, const liq_attr * options, + const liq_image * img) +{ + colormap *acolormap; + double palette_error = -1; + + // no point having perfect match with imperfect colors (ignorebits > 0) + const bool fast_palette = options->fast_palette || hist->ignorebits > 0; + const bool few_input_colors = + hist->size + img->fixed_colors_count <= options->max_colors; + liq_result *result; + + // If image has few colors to begin with (and no quality degradation is required) + // then it's possible to skip quantization entirely + if (few_input_colors && options->target_mse == 0) { + acolormap = pam_colormap (hist->size, options->malloc, options->free); + for (unsigned int i = 0; i < hist->size; i++) { + acolormap->palette[i].acolor = hist->achv[i].acolor; + acolormap->palette[i].popularity = hist->achv[i].perceptual_weight; + } + acolormap = + add_fixed_colors_to_palette (acolormap, options->max_colors, + img->fixed_colors, img->fixed_colors_count, options->malloc, + options->free); + palette_error = 0; + } else { + const double max_mse = options->max_mse * (few_input_colors ? 0.33 : 1.0); // when degrading image that's already paletted, require much higher improvement, since pal2pal often looks bad and there's little gain + const double iteration_limit = options->voronoi_iteration_limit; + unsigned int iterations = options->voronoi_iterations; + + acolormap = + find_best_palette (hist, options, max_mse, img->fixed_colors, + img->fixed_colors_count, &palette_error); + if (!acolormap) { + return NULL; + } + // Voronoi iteration approaches local minimum for the palette + if (!iterations && palette_error < 0 && max_mse < MAX_DIFF) + iterations = 1; // otherwise total error is never calculated and MSE limit won't work + + if (iterations) { + double previous_palette_error = MAX_DIFF; + unsigned int i; + + // likely_colormap_index (used and set in viter_do_iteration) can't point to index outside colormap + if (acolormap->colors < 256) + for (unsigned int j = 0; j < hist->size; j++) { + if (hist->achv[j].tmp.likely_colormap_index >= acolormap->colors) { + hist->achv[j].tmp.likely_colormap_index = 0; // actual value doesn't matter, as the guess is out of date anyway + } + } + + verbose_print (options, " moving colormap towards local minimum"); + + for (i = 0; i < iterations; i++) { + palette_error = + viter_do_iteration (hist, acolormap, options->min_opaque_val, NULL, + i == 0 || options->fast_palette); + + if (fabs (previous_palette_error - palette_error) < iteration_limit) { + break; + } + + if (palette_error > max_mse * 1.5) { // probably hopeless + if (palette_error > max_mse * 3.0) + break; // definitely hopeless + i++; + } + + previous_palette_error = palette_error; + } + } + + if (palette_error > max_mse) { + liq_verbose_printf (options, + " image degradation MSE=%.3f (Q=%d) exceeded limit of %.3f (%d)", + palette_error * 65536.0 / 6.0, mse_to_quality (palette_error), + max_mse * 65536.0 / 6.0, mse_to_quality (max_mse)); + pam_freecolormap (acolormap); + return NULL; + } + } + + sort_palette (acolormap, options); + + result = options->malloc (sizeof (liq_result)); + if (!result) + return NULL; + *result = (liq_result) { + .magic_header = liq_result_magic,.malloc = options->malloc,.free = + options->free,.palette = acolormap,.palette_error = + palette_error,.fast_palette = fast_palette,.use_dither_map = + options->use_dither_map,.gamma = + img->gamma,.min_posterization_output = + options->min_posterization_output,}; + return result; +} + +LIQ_EXPORT liq_error +liq_write_remapped_image (liq_result * result, liq_image * input_image, + void *buffer, size_t buffer_size) +{ + size_t required_size; + unsigned char **rows; + unsigned char *buffer_bytes; + unsigned i; + + if (!CHECK_STRUCT_TYPE (result, liq_result)) { + return LIQ_INVALID_POINTER; + } + if (!CHECK_STRUCT_TYPE (input_image, liq_image)) { + return LIQ_INVALID_POINTER; + } + if (!CHECK_USER_POINTER (buffer)) { + return LIQ_INVALID_POINTER; + } + + required_size = input_image->width * input_image->height; + if (buffer_size < required_size) { + return LIQ_BUFFER_TOO_SMALL; + } + + rows = g_alloca (sizeof (unsigned char *) * input_image->height); + buffer_bytes = buffer; + for (i = 0; i < input_image->height; i++) { + rows[i] = &buffer_bytes[input_image->width * i]; + } + return liq_write_remapped_image_rows (result, input_image, rows); +} + +LIQ_EXPORT liq_error +liq_write_remapped_image_rows (liq_result * quant, liq_image * input_image, + unsigned char **row_pointers) +{ + unsigned int i; + liq_remapping_result *result; + float remapping_error; + + if (!CHECK_STRUCT_TYPE (quant, liq_result)) + return LIQ_INVALID_POINTER; + if (!CHECK_STRUCT_TYPE (input_image, liq_image)) + return LIQ_INVALID_POINTER; + for (i = 0; i < input_image->height; i++) { + if (!CHECK_USER_POINTER (row_pointers + i) + || !CHECK_USER_POINTER (row_pointers[i])) + return LIQ_INVALID_POINTER; + } + + if (quant->remapping) { + liq_remapping_result_destroy (quant->remapping); + } + + result = quant->remapping = liq_remapping_result_create (quant); + if (!result) + return LIQ_OUT_OF_MEMORY; + + if (!input_image->edges && !input_image->dither_map && quant->use_dither_map) { + contrast_maps (input_image); + } + + /* + ** Step 4: map the colors in the image to their closest match in the + ** new colormap, and write 'em out. + */ + + remapping_error = result->palette_error; + if (result->dither_level == 0) { + set_rounded_palette (&result->int_palette, result->palette, result->gamma, + quant->min_posterization_output); + remapping_error = + remap_to_palette (input_image, row_pointers, result->palette, + quant->fast_palette); + } else { + const bool generate_dither_map = result->use_dither_map + && (input_image->edges && !input_image->dither_map); + if (generate_dither_map) { + // If dithering (with dither map) is required, this image is used to find areas that require dithering + remapping_error = + remap_to_palette (input_image, row_pointers, result->palette, + quant->fast_palette); + update_dither_map (row_pointers, input_image); + } + // remapping above was the last chance to do voronoi iteration, hence the final palette is set after remapping + set_rounded_palette (&result->int_palette, result->palette, result->gamma, + quant->min_posterization_output); + + remap_to_palette_floyd (input_image, row_pointers, result->palette, + MAX (remapping_error * 2.4, 16.f / 256.f), result->use_dither_map, + generate_dither_map, result->dither_level); + } + + // remapping error from dithered image is absurd, so always non-dithered value is used + // palette_error includes some perceptual weighting from histogram which is closer correlated with dssim + // so that should be used when possible. + if (result->palette_error < 0) { + result->palette_error = remapping_error; + } + + return LIQ_OK; +} + +LIQ_EXPORT int +liq_version (void) +{ + return LIQ_VERSION; +} |