libavfilter/palette.h

   1 /*
   2  * Copyright (c) 2020 Björn Ottosson
   3  * Copyright (c) 2022 Clément Bœsch <u pkh me>
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * FFmpeg is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with FFmpeg; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 #ifndef AVFILTER_PALETTE_H
  23 #define AVFILTER_PALETTE_H
  24
  25 #include <math.h>
  26 #include <stdint.h>
  27
  28 #include "libavutil/attributes.h"
  29
  30 struct Lab {
  31     int32_t L, a, b;
  32 };
  33
  34 /**
  35  * Map sRGB 8-bit color component to a 16-bit linear value (gamma
  36  * expand from electrical to optical value).
  37  */
  38 int32_t ff_srgb_u8_to_linear_int(uint8_t x);
  39
  40 /**
  41  * Map a 16-bit linear value to a sRGB 8-bit color component (gamma
  42  * compressed from optical to electrical value).
  43  */
  44 uint8_t ff_linear_int_to_srgb_u8(int32_t x);
  45
  46 /**
  47  * sRGB (non-linear) to OkLab conversion
  48  * @see https://bottosson.github.io/posts/oklab/
  49  */
  50 struct Lab ff_srgb_u8_to_oklab_int(uint32_t srgb);
  51
  52 /**
  53  * OkLab to sRGB (non-linear) conversion
  54  * @see https://bottosson.github.io/posts/oklab/
  55  */
  56 uint32_t ff_oklab_int_to_srgb_u8(struct Lab c);
  57
  58 /*
  59  * lowbias32 hashing from https://nullprogram.com/blog/2018/07/31/
  60  */
  61 uint32_t ff_lowbias32(uint32_t x);
  62
  63 #endif /* AVFILTER_PALETTE_H */