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/*
* img_enhance.c
*
* Part of a processor program for raw data from JL2005B/C/D cameras.
* Based on previous work for several other cameras.
*
* Copyright (c) 2010 Theodore Kilgore <kilgota@auburn.edu>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* A previous version of the white_balance() function intended for use in
* libgphoto2/camlibs/aox is copyright (c) 2008 Amauri Magagna.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU General Public
* License along with this program; if not, write to the
* Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301 USA
*/
#include <stdlib.h>
#include <stdio.h>
#include <fcntl.h>
#include <string.h>
#include <math.h>
#include <libgphoto2/gamma.h>
#include <libgphoto2/bayer.h>
#include "img_enhance.h"
#include <gphoto2/gphoto2.h>
#define GP_MODULE "jl2005c"
#ifndef CLIP
#define CLIP(x) ((x)<0?0:((x)>255)?255:(x))
#endif
/* ===== White Balance / Color Enhance / Gamma adjust =====
Get histogram for each color plane
Expand to reach 0.5% of white dots in image
Get new histogram for each color plane
Expand to reach 0.5% of black dots in image
Get new histogram
Calculate and apply gamma correction
If not a dark image:
For each dot, increase the color separation
========================================================== */
int
histogram (unsigned char *data, unsigned int size, int *htable_r,
int *htable_g, int *htable_b)
{
unsigned int x;
/* Initializations */
for (x = 0; x < 0x100; x++) {
htable_r[x] = 0;
htable_g[x] = 0;
htable_b[x] = 0;
}
/* Building the histograms */
for (x = 0; x < (size * 3); x += 3)
{
htable_r[data[x + 0]]++; /* red histogram */
htable_g[data[x + 1]]++; /* green histogram */
htable_b[data[x + 2]]++; /* blue histogram */
}
return 0;
}
int
white_balance (unsigned char *data, unsigned int size, float saturation)
{
unsigned int x, max;
int r, g, b, d;
double r_factor, g_factor, b_factor, max_factor;
int htable_r[0x100], htable_g[0x100], htable_b[0x100];
unsigned char gtable[0x100];
double new_gamma, gamma = 1.0;
/* ------------------- GAMMA CORRECTION ------------------- */
histogram(data, size, htable_r, htable_g, htable_b);
x = 1;
for (r = 64; r < 192; r++)
{
x += htable_r[r];
x += htable_g[r];
x += htable_b[r];
}
new_gamma = sqrt((double) (x * 1.5) / (double) (size * 3));
GP_DEBUG("Provisional gamma correction = %1.2f\n", new_gamma);
/* Recalculate saturation factor for later use. */
saturation = saturation * new_gamma * new_gamma;
GP_DEBUG("saturation = %1.2f\n", saturation);
gamma = new_gamma;
if (new_gamma < .70)
gamma = 0.70;
if (new_gamma > 1.2)
gamma = 1.2;
GP_DEBUG("Gamma correction = %1.2f\n", gamma);
gp_gamma_fill_table(gtable, gamma);
gp_gamma_correct_single(gtable, data, size);
if (saturation < .5 ) /* If so, exit now. */
return 0;
/* ---------------- BRIGHT DOTS ------------------- */
max = size / 200;
histogram(data, size, htable_r, htable_g, htable_b);
for (r = 0xfe, x = 0; (r > 32) && (x < max); r--)
x += htable_r[r];
for (g = 0xfe, x = 0; (g > 32) && (x < max); g--)
x += htable_g[g];
for (b = 0xfe, x = 0; (b > 32) && (x < max); b--)
x += htable_b[b];
r_factor = (double) 0xfd / r;
g_factor = (double) 0xfd / g;
b_factor = (double) 0xfd / b;
max_factor = r_factor;
if (g_factor > max_factor) max_factor = g_factor;
if (b_factor > max_factor) max_factor = b_factor;
if (max_factor >= 4.0) {
/*
* We need a little bit of control, here. If max_factor is big
* then the photo was very dark, after all.
*/
if (2.0 * b_factor < max_factor)
b_factor = max_factor / 2.;
if (2.0 * r_factor < max_factor)
r_factor = max_factor / 2.;
if (2.0 * g_factor < max_factor)
g_factor = max_factor/2.;
r_factor = (r_factor / max_factor) * 4.0;
g_factor = (g_factor / max_factor) * 4.0;
b_factor = (b_factor / max_factor) * 4.0;
}
if (max_factor > 1.5)
saturation = 0;
GP_DEBUG("White balance (bright): ");
GP_DEBUG("r=%1d, g=%1d, b=%1d, fr=%1.3f, fg=%1.3f, fb=%1.3f\n",
r, g, b, r_factor, g_factor, b_factor);
if (max_factor <= 1.4) {
for (x = 0; x < (size * 3); x += 3)
{
d = (data[x + 0] << 8) * r_factor + 8;
d >>= 8;
if (d > 0xff)
d = 0xff;
data[x + 0] = d;
d = (data[x + 1] << 8) * g_factor + 8;
d >>= 8;
if (d > 0xff)
d = 0xff;
data[x + 1] = d;
d = (data[x + 2] << 8) * b_factor + 8;
d >>= 8;
if (d > 0xff)
d = 0xff;
data[x + 2] = d;
}
}
/* ---------------- DARK DOTS ------------------- */
max = size / 200; /* 1/200 = 0.5% */
histogram(data, size, htable_r, htable_g, htable_b);
for (r = 0, x = 0; (r < 96) && (x < max); r++)
x += htable_r[r];
for (g = 0, x = 0; (g < 96) && (x < max); g++)
x += htable_g[g];
for (b = 0, x = 0; (b < 96) && (x < max); b++)
x += htable_b[b];
r_factor = (double) 0xfe / (0xff - r);
g_factor = (double) 0xfe / (0xff - g);
b_factor = (double) 0xfe / (0xff - b);
GP_DEBUG("White balance (dark): ");
GP_DEBUG("r=%1d, g=%1d, b=%1d, fr=%1.3f, fg=%1.3f, fb=%1.3f\n",
r, g, b, r_factor, g_factor, b_factor);
for (x = 0; x < (size * 3); x += 3)
{
d = (int) 0xff08 - (((0xff - data[x + 0]) << 8) * r_factor);
d >>= 8;
if (d < 0)
d = 0;
data[x + 0] = d;
d = (int) 0xff08 - (((0xff - data[x + 1]) << 8) * g_factor);
d >>= 8;
if (d < 0)
d = 0;
data[x + 1] = d;
d = (int) 0xff08 - (((0xff - data[x + 2]) << 8) * b_factor);
d >>= 8;
if (d < 0)
d = 0;
data[x + 2] = d;
}
/* ------------------ COLOR ENHANCE ------------------ */
if(saturation > 0.0) {
for (x = 0; x < (size * 3); x += 3)
{
r = data[x + 0]; g = data[x + 1]; b = data[x + 2];
d = (int) (r + g + b) / 3.;
if ( r > d )
r = r + (int) ((r - d)
* (0xff - r) / (0x100 - d)
* saturation);
else
r = r + (int) ((r - d)
* (0xff - d) / (0x100 - r)
* saturation);
if (g > d)
g = g + (int) ((g - d)
* (0xff - g) / (0x100 - d)
* saturation);
else
g = g + (int) ((g - d)
* (0xff - d) / (0x100 - g)
* saturation);
if (b > d)
b = b + (int) ((b - d)
* (0xff - b) / (0x100 - d)
* saturation);
else
b = b + (int) ((b - d)
* (0xff - d) / (0x100 - b)
* saturation);
data[x + 0] = CLIP(r);
data[x + 1] = CLIP(g);
data[x + 2] = CLIP(b);
}
}
return 0;
}
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