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/*
* Common code related to colorspaces and conversion
*
* Copyleft (C) 2009 Reimar Döffinger <Reimar.Doeffinger@gmx.de>
*
* This file is part of MPlayer.
*
* MPlayer 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.
*
* MPlayer 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with MPlayer; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <stdint.h>
#include <math.h>
#include "libavutil/common.h"
#include "csputils.h"
/**
* \brief little helper function to create a lookup table for gamma
* \param map buffer to create map into
* \param size size of buffer
* \param gamma gamma value
*/
void mp_gen_gamma_map(uint8_t *map, int size, float gamma) {
int i;
if (gamma == 1.0) {
for (i = 0; i < size; i++)
map[i] = 255 * i / (size - 1);
return;
}
gamma = 1.0 / gamma;
for (i = 0; i < size; i++) {
float tmp = (float)i / (size - 1.0);
tmp = pow(tmp, gamma);
if (tmp > 1.0) tmp = 1.0;
if (tmp < 0.0) tmp = 0.0;
map[i] = 255 * tmp;
}
}
/**
* \brief get the coefficients of the yuv -> rgb conversion matrix
* \param params struct specifying the properties of the conversion like brightness, ...
* \param yuv2rgb array to store coefficients into
*/
void mp_get_yuv2rgb_coeffs(struct mp_csp_params *params, float yuv2rgb[3][4]) {
float uvcos = params->saturation * cos(params->hue);
float uvsin = params->saturation * sin(params->hue);
int i;
float uv_coeffs[3][2] = {
{ 0.000, 1.596},
{-0.391, -0.813},
{ 2.018, 0.000}
};
for (i = 0; i < 3; i++) {
yuv2rgb[i][COL_C] = params->brightness;
yuv2rgb[i][COL_Y] = 1.164 * params->contrast;
yuv2rgb[i][COL_C] += (-16 / 255.0) * yuv2rgb[i][COL_Y];
yuv2rgb[i][COL_U] = uv_coeffs[i][0] * uvcos + uv_coeffs[i][1] * uvsin;
yuv2rgb[i][COL_C] += (-128 / 255.0) * yuv2rgb[i][COL_U];
yuv2rgb[i][COL_V] = uv_coeffs[i][0] * uvsin + uv_coeffs[i][1] * uvcos;
yuv2rgb[i][COL_C] += (-128 / 255.0) * yuv2rgb[i][COL_V];
// this "centers" contrast control so that e.g. a contrast of 0
// leads to a grey image, not a black one
yuv2rgb[i][COL_C] += 0.5 - params->contrast / 2.0;
}
}
//! size of gamma map use to avoid slow exp function in gen_yuv2rgb_map
#define GMAP_SIZE (1024)
/**
* \brief generate a 3D YUV -> RGB map
* \param params struct containing parameters like brightness, gamma, ...
* \param map where to store map. Must provide space for (size + 2)^3 elements
* \param size size of the map, excluding border
*/
void mp_gen_yuv2rgb_map(struct mp_csp_params *params, unsigned char *map, int size) {
int i, j, k, l;
float step = 1.0 / size;
float y, u, v;
float yuv2rgb[3][4];
unsigned char gmaps[3][GMAP_SIZE];
mp_gen_gamma_map(gmaps[0], GMAP_SIZE, params->rgamma);
mp_gen_gamma_map(gmaps[1], GMAP_SIZE, params->ggamma);
mp_gen_gamma_map(gmaps[2], GMAP_SIZE, params->bgamma);
mp_get_yuv2rgb_coeffs(params, yuv2rgb);
for (i = 0; i < 3; i++)
for (j = 0; j < 4; j++)
yuv2rgb[i][j] *= GMAP_SIZE - 1;
v = 0;
for (i = -1; i <= size; i++) {
u = 0;
for (j = -1; j <= size; j++) {
y = 0;
for (k = -1; k <= size; k++) {
for (l = 0; l < 3; l++) {
float rgb = yuv2rgb[l][COL_Y] * y + yuv2rgb[l][COL_U] * u + yuv2rgb[l][COL_V] * v + yuv2rgb[l][COL_C];
*map++ = gmaps[l][av_clip(rgb, 0, GMAP_SIZE - 1)];
}
y += (k == -1 || k == size - 1) ? step / 2 : step;
}
u += (j == -1 || j == size - 1) ? step / 2 : step;
}
v += (i == -1 || i == size - 1) ? step / 2 : step;
}
}
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