From 6daba723729971d103f87ed9b55ac758cd0667f7 Mon Sep 17 00:00:00 2001
From: xufuji456 <xufl@flatincbr.com>
Date: Sat, 9 Jul 2022 11:26:01 +0800
Subject: [PATCH] Feature: yuv to rgb formula

---
 app/src/main/cpp/yuv2rgb/yuv_2_rgb.cpp | 31 ++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/app/src/main/cpp/yuv2rgb/yuv_2_rgb.cpp b/app/src/main/cpp/yuv2rgb/yuv_2_rgb.cpp
index 9b891cf..044fcbc 100644
--- a/app/src/main/cpp/yuv2rgb/yuv_2_rgb.cpp
+++ b/app/src/main/cpp/yuv2rgb/yuv_2_rgb.cpp
@@ -4,6 +4,37 @@
 
 #include "yuv_to_rgb.h"
 
+// https://chromium.googlesource.com/libyuv/libyuv
+// https://mymusing.co/bt601-yuv-to-rgb-conversion-color/
+// https://www.color.org/chardata/rgb/rgb_registry.xalter
+
+// BT.601 YUV to RGB
+// R = 1.164 * (Y - 16) + 1.596 * (V - 128)
+// G = 1.164 * (Y - 16) - 0.392 * (U - 128) - 0.812 * (V - 128)
+// B = 1.164 * (Y - 16) + 2.016 * (U - 128)
+
+// Y = 0.257 * R + 0.504 * G + 0.098 * B + 16
+// U = -0.148 * R - 0.291 * G + 0.439 * B + 128
+// V = 0.439 * R - 0.368 * G - 0.072 * B + 128
+
+// BT.709 YUV to RGB
+// R = 1.1644 * (Y - 16) + 1.7928 * (V - 128)
+// G = 1.1644 * (Y - 16) - 0.2133 * (U - 128) - 0.533 * (V - 128)
+// B = 1.1644 * (Y - 16) + 2.1124 * (U - 128)
+
+// Y = 0.1826 * R + 0.6142 * G + 0.0620 * B + 16
+// U = -0.1006 * R - 0.3386 * G + 0.4392 * B + 128
+// V = 0.4392 * B - 0.3989 * G - 0.0403 * B + 128
+
+// BT.2020 YUV to RGB
+// R = Y - 16 + 1.4746 * (V - 128)
+// G = Y - 16 - 0.1645 * (U - 128) - 0.5713 * (V - 128)
+// B = Y - 16 + 1.881 * (U - 128)
+
+// Y = 0.2627 * R + 0.6780 * G + 0.0593 * B + 16
+// U = -0.1396 * R - 0.3604 * G + 0.5 * B + 128
+// V = 0.5 * R - 0.4598 * G - 0.0402 * B + 128
+
 static int range(int val) {
     if (val < 0) {
         return 0;