forked from openkylin/gimp
97 lines
2.6 KiB
C
97 lines
2.6 KiB
C
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/*
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* DDS GIMP plugin
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*
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* Copyright (C) 2004-2012 Shawn Kirst <skirst@gmail.com>,
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* with parts (C) 2003 Arne Reuter <homepage@arnereuter.de> where specified.
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*
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* This program 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 3 of the License, or
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* (at your option) any later version.
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*
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* This program 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
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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#ifndef __COLOR_H__
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#define __COLOR_H__
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#include "imath.h"
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/* sRGB encoding/decoding */
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int linear_to_sRGB(int c);
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int sRGB_to_linear(int c);
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/* YCoCg encoding */
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static inline void
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RGB_to_YCoCg (unsigned char *dst, int r, int g, int b)
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{
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int y = ((r + (g << 1) + b) + 2) >> 2;
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int co = ((((r << 1) - (b << 1)) + 2) >> 2) + 128;
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int cg = (((-r + (g << 1) - b) + 2) >> 2) + 128;
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dst[0] = 255;
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dst[1] = (cg > 255 ? 255 : (cg < 0 ? 0 : cg));
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dst[2] = (co > 255 ? 255 : (co < 0 ? 0 : co));
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dst[3] = (y > 255 ? 255 : (y < 0 ? 0 : y));
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}
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/* other color conversions */
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static inline int
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rgb_to_luminance (int r, int g, int b)
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{
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/* ITU-R BT.709 luma coefficients, scaled by 256 */
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return ((r * 54 + g * 182 + b * 20) + 128) >> 8;
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}
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static inline unsigned short
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pack_r5g6b5 (int r, int g, int b)
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{
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return (mul8bit(r, 31) << 11) |
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(mul8bit(g, 63) << 5) |
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(mul8bit(b, 31) );
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}
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static inline unsigned short
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pack_rgba4 (int r, int g, int b, int a)
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{
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return (mul8bit(a, 15) << 12) |
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(mul8bit(r, 15) << 8) |
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(mul8bit(g, 15) << 4) |
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(mul8bit(b, 15) );
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}
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static inline unsigned short
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pack_rgb5a1 (int r, int g, int b, int a)
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{
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return (((a >> 7) & 0x01) << 15) |
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(mul8bit(r, 31) << 10) |
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(mul8bit(g, 31) << 5) |
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(mul8bit(b, 31) );
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}
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static inline unsigned char
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pack_r3g3b2(int r, int g, int b)
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{
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return (mul8bit(r, 7) << 5) |
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(mul8bit(g, 7) << 2) |
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(mul8bit(b, 3) );
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}
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static inline unsigned int
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pack_rgb10a2 (int r, int g, int b, int a)
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{
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return ((unsigned int)((a >> 6) & 0x003) << 30) |
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((unsigned int)((b << 2) & 0x3ff) << 20) |
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((unsigned int)((g << 2) & 0x3ff) << 10) |
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((unsigned int)((r << 2) & 0x3ff) );
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}
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#endif /* __COLOR_H__ */
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