colorbalance_lib.c
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00001 /* 00002 * Copyright 2009-2011 IPOL Image Processing On Line http://www.ipol.im/ 00003 * 00004 * This program is free software: you can redistribute it and/or modify 00005 * it under the terms of the GNU General Public License as published by 00006 * the Free Software Foundation, either version 3 of the License, or 00007 * (at your option) any later version. 00008 * 00009 * This program is distributed in the hope that it will be useful, 00010 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00011 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00012 * GNU General Public License for more details. 00013 * 00014 * You should have received a copy of the GNU General Public License 00015 * along with this program. If not, see <http://www.gnu.org/licenses/>. 00016 */ 00017 00029 #include <stdlib.h> 00030 #include <string.h> 00031 #include <stdio.h> 00032 #include <float.h> 00033 00034 #include "balance_lib.h" 00035 00036 /* ensure consistency */ 00037 #include "colorbalance_lib.h" 00038 00046 unsigned char *colorbalance_rgb_u8(unsigned char *rgb, size_t size, 00047 size_t nb_min, size_t nb_max) 00048 { 00049 (void) balance_u8(rgb, size, nb_min, nb_max); 00050 (void) balance_u8(rgb + size, size, nb_min, nb_max); 00051 (void) balance_u8(rgb + 2 * size, size, nb_min, nb_max); 00052 return rgb; 00053 } 00054 00056 #define MAX(A,B) (((A) >= (B)) ? (A) : (B)) 00057 00059 #define MAX3(A,B,C) (((A) >= (B)) ? MAX(A,C) : MAX(B,C)) 00060 00072 float *colorbalance_irgb_f32(float *rgb, size_t size, 00073 size_t nb_min, size_t nb_max) 00074 { 00075 float *irgb, *inorm; /* intensity scale */ 00076 double s, m; 00077 size_t i; 00079 irgb = (float *) malloc(size * sizeof(float)); 00080 for (i = 0; i < size; i++) 00081 irgb[i] = (rgb[i] + rgb[i + size] + rgb[i + 2 * size]) / 3.; 00082 /* copy and normalize I */ 00083 inorm = (float *) malloc(size * sizeof(float)); 00084 memcpy(inorm, irgb, size * sizeof(float)); 00085 (void) balance_f32(inorm, size, nb_min, nb_max); 00086 /* 00087 * apply the I normalization to the RGB channels: 00088 * RGB = RGB * Inorm / I, with a projection towards (0,0,0) 00089 * on the RGB cube if needed 00090 */ 00091 for (i = 0; i < size; i++) { 00092 m = MAX3(rgb[i], rgb[i + size], rgb[i + 2 * size]); 00093 s = inorm[i] / irgb[i]; 00094 /* if m * s > 1, a projection is needed by adjusting s */ 00095 s = (1. < m * s ? 1. / m : s); 00096 rgb[i] *= s; 00097 rgb[i + size] *= s; 00098 rgb[i + 2 * size] *= s; 00099 } 00100 free(irgb); 00101 free(inorm); 00102 return rgb; 00103 }
