mirror of https://github.com/mpv-player/mpv
117 lines
4.0 KiB
C
117 lines
4.0 KiB
C
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/*
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* Common code related to colorspaces and conversion
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*
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* Copyleft (C) 2009 Reimar Döffinger <Reimar.Doeffinger@gmx.de>
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*
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* This file is part of MPlayer.
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*
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* MPlayer is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* MPlayer is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with MPlayer; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include <stdint.h>
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#include <math.h>
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#include "libavutil/common.h"
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#include "csputils.h"
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/**
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* \brief little helper function to create a lookup table for gamma
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* \param map buffer to create map into
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* \param size size of buffer
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* \param gamma gamma value
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*/
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void mp_gen_gamma_map(uint8_t *map, int size, float gamma) {
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int i;
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if (gamma == 1.0) {
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for (i = 0; i < size; i++)
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map[i] = 255 * i / (size - 1);
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return;
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}
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gamma = 1.0 / gamma;
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for (i = 0; i < size; i++) {
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float tmp = (float)i / (size - 1.0);
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tmp = pow(tmp, gamma);
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if (tmp > 1.0) tmp = 1.0;
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if (tmp < 0.0) tmp = 0.0;
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map[i] = 255 * tmp;
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}
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}
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/**
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* \brief get the coefficients of the yuv -> rgb conversion matrix
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* \param params struct specifying the properties of the conversion like brightness, ...
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* \param yuv2rgb array to store coefficients into
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*/
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void mp_get_yuv2rgb_coeffs(struct mp_csp_params *params, float yuv2rgb[3][4]) {
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float uvcos = params->saturation * cos(params->hue);
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float uvsin = params->saturation * sin(params->hue);
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int i;
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float uv_coeffs[3][2] = {
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{ 0.000, 1.596},
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{-0.391, -0.813},
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{ 2.018, 0.000}
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};
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for (i = 0; i < 3; i++) {
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yuv2rgb[i][COL_C] = params->brightness;
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yuv2rgb[i][COL_Y] = 1.164 * params->contrast;
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yuv2rgb[i][COL_C] += (-16 / 255.0) * yuv2rgb[i][COL_Y];
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yuv2rgb[i][COL_U] = uv_coeffs[i][0] * uvcos + uv_coeffs[i][1] * uvsin;
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yuv2rgb[i][COL_C] += (-128 / 255.0) * yuv2rgb[i][COL_U];
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yuv2rgb[i][COL_V] = uv_coeffs[i][0] * uvsin + uv_coeffs[i][1] * uvcos;
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yuv2rgb[i][COL_C] += (-128 / 255.0) * yuv2rgb[i][COL_V];
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// this "centers" contrast control so that e.g. a contrast of 0
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// leads to a grey image, not a black one
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yuv2rgb[i][COL_C] += 0.5 - params->contrast / 2.0;
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}
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}
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//! size of gamma map use to avoid slow exp function in gen_yuv2rgb_map
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#define GMAP_SIZE (1024)
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/**
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* \brief generate a 3D YUV -> RGB map
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* \param params struct containing parameters like brightness, gamma, ...
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* \param map where to store map. Must provide space for (size + 2)^3 elements
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* \param size size of the map, excluding border
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*/
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void mp_gen_yuv2rgb_map(struct mp_csp_params *params, unsigned char *map, int size) {
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int i, j, k, l;
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float step = 1.0 / size;
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float y, u, v;
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float yuv2rgb[3][4];
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unsigned char gmaps[3][GMAP_SIZE];
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mp_gen_gamma_map(gmaps[0], GMAP_SIZE, params->rgamma);
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mp_gen_gamma_map(gmaps[1], GMAP_SIZE, params->ggamma);
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mp_gen_gamma_map(gmaps[2], GMAP_SIZE, params->bgamma);
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mp_get_yuv2rgb_coeffs(params, yuv2rgb);
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for (i = 0; i < 3; i++)
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for (j = 0; j < 4; j++)
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yuv2rgb[i][j] *= GMAP_SIZE - 1;
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v = 0;
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for (i = -1; i <= size; i++) {
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u = 0;
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for (j = -1; j <= size; j++) {
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y = 0;
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for (k = -1; k <= size; k++) {
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for (l = 0; l < 3; l++) {
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float rgb = yuv2rgb[l][COL_Y] * y + yuv2rgb[l][COL_U] * u + yuv2rgb[l][COL_V] * v + yuv2rgb[l][COL_C];
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*map++ = gmaps[l][av_clip(rgb, 0, GMAP_SIZE - 1)];
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}
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y += (k == -1 || k == size - 1) ? step / 2 : step;
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}
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u += (j == -1 || j == size - 1) ? step / 2 : step;
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}
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v += (i == -1 || i == size - 1) ? step / 2 : step;
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}
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}
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