| /* |
| * Copyright (c) 2015 Kevin Wheatley <kevin.j.wheatley@gmail.com> |
| * |
| * This file is part of FFmpeg. |
| * |
| * FFmpeg is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU Lesser General Public |
| * License as published by the Free Software Foundation; either |
| * version 2.1 of the License, or (at your option) any later version. |
| * |
| * FFmpeg 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 |
| * Lesser General Public License for more details. |
| * |
| * You should have received a copy of the GNU Lesser General Public |
| * License along with FFmpeg; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| */ |
| |
| #include <stddef.h> |
| #include <math.h> |
| |
| #include "libavutil/color_utils.h" |
| #include "libavutil/pixfmt.h" |
| |
| double avpriv_get_gamma_from_trc(enum AVColorTransferCharacteristic trc) |
| { |
| double gamma; |
| switch (trc) { |
| case AVCOL_TRC_BT709: |
| case AVCOL_TRC_SMPTE170M: |
| case AVCOL_TRC_SMPTE240M: |
| case AVCOL_TRC_BT1361_ECG: |
| case AVCOL_TRC_BT2020_10: |
| case AVCOL_TRC_BT2020_12: |
| /* these share a segmented TRC, but gamma 1.961 is a close |
| approximation, and also more correct for decoding content */ |
| gamma = 1.961; |
| break; |
| case AVCOL_TRC_GAMMA22: |
| case AVCOL_TRC_IEC61966_2_1: |
| gamma = 2.2; |
| break; |
| case AVCOL_TRC_GAMMA28: |
| gamma = 2.8; |
| break; |
| case AVCOL_TRC_LINEAR: |
| gamma = 1.0; |
| break; |
| default: |
| gamma = 0.0; // Unknown value representation |
| } |
| return gamma; |
| } |
| |
| #define BT709_alpha 1.099296826809442 |
| #define BT709_beta 0.018053968510807 |
| |
| static double avpriv_trc_bt709(double Lc) |
| { |
| const double a = BT709_alpha; |
| const double b = BT709_beta; |
| |
| return (0.0 > Lc) ? 0.0 |
| : ( b > Lc) ? 4.500 * Lc |
| : a * pow(Lc, 0.45) - (a - 1.0); |
| } |
| |
| static double avpriv_trc_gamma22(double Lc) |
| { |
| return (0.0 > Lc) ? 0.0 : pow(Lc, 1.0/ 2.2); |
| } |
| |
| static double avpriv_trc_gamma28(double Lc) |
| { |
| return (0.0 > Lc) ? 0.0 : pow(Lc, 1.0/ 2.8); |
| } |
| |
| static double avpriv_trc_smpte240M(double Lc) |
| { |
| const double a = 1.1115; |
| const double b = 0.0228; |
| |
| return (0.0 > Lc) ? 0.0 |
| : ( b > Lc) ? 4.000 * Lc |
| : a * pow(Lc, 0.45) - (a - 1.0); |
| } |
| |
| static double avpriv_trc_linear(double Lc) |
| { |
| return Lc; |
| } |
| |
| static double avpriv_trc_log(double Lc) |
| { |
| return (0.01 > Lc) ? 0.0 : 1.0 + log10(Lc) / 2.0; |
| } |
| |
| static double avpriv_trc_log_sqrt(double Lc) |
| { |
| // sqrt(10) / 1000 |
| return (0.00316227766 > Lc) ? 0.0 : 1.0 + log10(Lc) / 2.5; |
| } |
| |
| static double avpriv_trc_iec61966_2_4(double Lc) |
| { |
| const double a = BT709_alpha; |
| const double b = BT709_beta; |
| |
| return (-b >= Lc) ? -a * pow(-Lc, 0.45) + (a - 1.0) |
| : ( b > Lc) ? 4.500 * Lc |
| : a * pow( Lc, 0.45) - (a - 1.0); |
| } |
| |
| static double avpriv_trc_bt1361(double Lc) |
| { |
| const double a = BT709_alpha; |
| const double b = BT709_beta; |
| |
| return (-0.0045 >= Lc) ? -(a * pow(-4.0 * Lc, 0.45) + (a - 1.0)) / 4.0 |
| : ( b > Lc) ? 4.500 * Lc |
| : a * pow( Lc, 0.45) - (a - 1.0); |
| } |
| |
| static double avpriv_trc_iec61966_2_1(double Lc) |
| { |
| const double a = 1.055; |
| const double b = 0.0031308; |
| |
| return (0.0 > Lc) ? 0.0 |
| : ( b > Lc) ? 12.92 * Lc |
| : a * pow(Lc, 1.0 / 2.4) - (a - 1.0); |
| } |
| |
| static double avpriv_trc_smpte_st2084(double Lc) |
| { |
| const double c1 = 3424.0 / 4096.0; // c3-c2 + 1 |
| const double c2 = 32.0 * 2413.0 / 4096.0; |
| const double c3 = 32.0 * 2392.0 / 4096.0; |
| const double m = 128.0 * 2523.0 / 4096.0; |
| const double n = 0.25 * 2610.0 / 4096.0; |
| const double L = Lc / 10000.0; |
| const double Ln = pow(L, n); |
| |
| return (0.0 > Lc) ? 0.0 |
| : pow((c1 + c2 * Ln) / (1.0 + c3 * Ln), m); |
| |
| } |
| |
| static double avpriv_trc_smpte_st428_1(double Lc) |
| { |
| return (0.0 > Lc) ? 0.0 |
| : pow(48.0 * Lc / 52.37, 1.0 / 2.6); |
| } |
| |
| avpriv_trc_function avpriv_get_trc_function_from_trc(enum AVColorTransferCharacteristic trc) |
| { |
| avpriv_trc_function func = NULL; |
| switch (trc) { |
| case AVCOL_TRC_BT709: |
| case AVCOL_TRC_SMPTE170M: |
| case AVCOL_TRC_BT2020_10: |
| case AVCOL_TRC_BT2020_12: |
| func = avpriv_trc_bt709; |
| break; |
| |
| case AVCOL_TRC_GAMMA22: |
| func = avpriv_trc_gamma22; |
| break; |
| case AVCOL_TRC_GAMMA28: |
| func = avpriv_trc_gamma28; |
| break; |
| |
| case AVCOL_TRC_SMPTE240M: |
| func = avpriv_trc_smpte240M; |
| break; |
| |
| case AVCOL_TRC_LINEAR: |
| func = avpriv_trc_linear; |
| break; |
| |
| case AVCOL_TRC_LOG: |
| func = avpriv_trc_log; |
| break; |
| |
| case AVCOL_TRC_LOG_SQRT: |
| func = avpriv_trc_log_sqrt; |
| break; |
| |
| case AVCOL_TRC_IEC61966_2_4: |
| func = avpriv_trc_iec61966_2_4; |
| break; |
| |
| case AVCOL_TRC_BT1361_ECG: |
| func = avpriv_trc_bt1361; |
| break; |
| |
| case AVCOL_TRC_IEC61966_2_1: |
| func = avpriv_trc_iec61966_2_1; |
| break; |
| |
| case AVCOL_TRC_SMPTEST2084: |
| func = avpriv_trc_smpte_st2084; |
| break; |
| |
| case AVCOL_TRC_SMPTEST428_1: |
| func = avpriv_trc_smpte_st428_1; |
| break; |
| |
| case AVCOL_TRC_RESERVED0: |
| case AVCOL_TRC_UNSPECIFIED: |
| case AVCOL_TRC_RESERVED: |
| default: |
| break; |
| } |
| return func; |
| } |