diff options
Diffstat (limited to 'media/libyuv/libyuv/util/yuvconstants.c')
| -rw-r--r-- | media/libyuv/libyuv/util/yuvconstants.c | 106 |
1 files changed, 106 insertions, 0 deletions
diff --git a/media/libyuv/libyuv/util/yuvconstants.c b/media/libyuv/libyuv/util/yuvconstants.c new file mode 100644 index 0000000000..bc0c0de28e --- /dev/null +++ b/media/libyuv/libyuv/util/yuvconstants.c @@ -0,0 +1,106 @@ +/* + * Copyright 2021 The LibYuv Project Authors. All rights reserved. + * + * Use of this source code is governed by a BSD-style license + * that can be found in the LICENSE file in the root of the source + * tree. An additional intellectual property rights grant can be found + * in the file PATENTS. All contributing project authors may + * be found in the AUTHORS file in the root of the source tree. + */ + +#include <math.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> + +// This utility computes values needed to generate yuvconstants based on +// white point values. +// The yuv formulas are tuned for 8 bit YUV channels. + +// See Also +// https://mymusing.co/bt601-yuv-to-rgb-conversion-color/ + +// BT.709 full range YUV to RGB reference +// R = Y + V * 1.5748 +// G = Y - U * 0.18732 - V * 0.46812 +// B = Y + U * 1.8556 +// KR = 0.2126 +// KB = 0.0722 + +// // Y contribution to R,G,B. Scale and bias. +// #define YG 16320 /* round(1.000 * 64 * 256 * 256 / 257) */ +// #define YB 32 /* 64 / 2 */ +// +// // U and V contributions to R,G,B. +// #define UB 113 /* round(1.77200 * 64) */ +// #define UG 22 /* round(0.34414 * 64) */ +// #define VG 46 /* round(0.71414 * 64) */ +// #define VR 90 /* round(1.40200 * 64) */ +// +// // Bias values to round, and subtract 128 from U and V. +// #define BB (-UB * 128 + YB) +// #define BG (UG * 128 + VG * 128 + YB) +// #define BR (-VR * 128 + YB) + +int main(int argc, const char* argv[]) { + if (argc < 3) { + printf("yuvconstants [KR] [KB]\n"); + printf(" e.g. yuvconstants 0.2126 0.0722\n"); + printf(" MC BT KR KB\n"); + printf(" 1 BT.709 KR = 0.2126; KB = 0.0722\n"); + printf(" 4 FCC KR = 0.30; KB = 0.11\n"); + printf(" 6 BT.601 KR = 0.299; KB = 0.114\n"); + printf(" 7 SMPTE 240M KR = 0.212; KB = 0.087\n"); + printf(" 9 BT.2020 KR = 0.2627; KB = 0.0593\n"); + return -1; + } + float kr = atof(argv[1]); + float kb = atof(argv[2]); + float kg = 1 - kr - kb; + + float vr = 2 * (1 - kr); + float ug = 2 * ((1 - kb) * kb / kg); + float vg = 2 * ((1 - kr) * kr / kg); + float ub = 2 * (1 - kb); + + printf("Full range\n"); + printf("R = Y + V * %5f\n", vr); + printf("G = Y - U * %6f - V * %6f\n", ug, vg); + printf("B = Y + U * %5f\n", ub); + + printf("KR = %4f; ", kr); + printf("KB = %4f\n", kb); + // printf("KG = %4f\n", kg); + // #define YG 16320 /* round(1.000 * 64 * 256 * 256 / 257) */ + // #define YB 32 /* 64 / 2 */ + // + // // U and V contributions to R,G,B. + + printf("UB %-3.0f /* round(%f * 64 = %8.4f) */\n", round(ub * 64), ub, ub * 64); + printf("UG %-3.0f /* round(%f * 64 = %8.4f) */\n", round(ug * 64), ug, ug * 64); + printf("VG %-3.0f /* round(%f * 64 = %8.4f) */\n", round(vg * 64), vg, vg * 64); + printf("VR %-3.0f /* round(%f * 64 = %8.4f) */\n", round(vr * 64), vr, vr * 64); + + vr = 255.f / 224.f * 2 * (1 - kr); + ug = 255.f / 224.f * 2 * ((1 - kb) * kb / kg); + vg = 255.f / 224.f * 2 * ((1 - kr) * kr / kg); + ub = 255.f / 224.f * 2 * (1 - kb); + + printf("\nLimited range\n"); + printf("R = (Y - 16) * 1.164 + V * %5f\n", vr); + printf("G = (Y - 16) * 1.164 - U * %6f - V * %6f\n", ug, vg); + printf("B = (Y - 16) * 1.164 + U * %5f\n", ub); + + // printf("KG = %4f\n", kg); + // #define YG 16320 /* round(1.000 * 64 * 256 * 256 / 257) */ + // #define YB 32 /* 64 / 2 */ + // + // // U and V contributions to R,G,B. + + printf("UB %-3.0f /* round(%f * 64 = %8.4f) */\n", round(ub * 64), ub, ub * 64); + printf("UG %-3.0f /* round(%f * 64 = %8.4f) */\n", round(ug * 64), ug, ug * 64); + printf("VG %-3.0f /* round(%f * 64 = %8.4f) */\n", round(vg * 64), vg, vg * 64); + printf("VR %-3.0f /* round(%f * 64 = %8.4f) */\n", round(vr * 64), vr, vr * 64); + + return 0; +} |