BLI Color: YUV to/from rgb colorspace option

This commit does two things:

- Adds an option to do the calculation in different color spaces (BT601
or BT709).
- Changes the default caluclation from legacy BT601 to BT709.

This affects several areas:

- UI areas (mainly scopes)
- ViewLevelsNode
- Several other nodes that use `COM_ConvertOperation.h`

2 files changed, 35 insertions, 11 deletions

diff --git a/source/blender/blenlib/BLI_math_color.h b/source/blender/blenlib/BLI_math_color.h
index 34fc52c12c0..72d29164988 100644
--- a/source/blender/blenlib/BLI_math_color.h
+++ b/source/blender/blenlib/BLI_math_color.h
@@ -51,6 +51,10 @@ extern "C" {
 #define BLI_YCC_ITU_BT709   1
 #define BLI_YCC_JFIF_0_255  2
 
+/* YUV */
+#define BLI_YUV_ITU_BT601   0
+#define BLI_YUV_ITU_BT709   1
+
 /******************* Conversion to RGB ********************/
 
 void hsv_to_rgb(float h, float s, float v, float *r, float *g, float *b);
@@ -58,14 +62,14 @@ void hsv_to_rgb_v(const float hsv[3], float r_rgb[3]);
 void hsl_to_rgb(float h, float c, float l, float *r, float *g, float *b);
 void hsl_to_rgb_v(const float hcl[3], float r_rgb[3]);
 void hex_to_rgb(char *hexcol, float *r, float *g, float *b);
-void yuv_to_rgb(float y, float u, float v, float *lr, float *lg, float *lb);
+void yuv_to_rgb(float y, float u, float v, float *lr, float *lg, float *lb, int colorspace);
 void ycc_to_rgb(float y, float cb, float cr, float *lr, float *lg, float *lb, int colorspace);
 void xyz_to_rgb(float x, float y, float z, float *r, float *g, float *b, int colorspace);
 void cpack_to_rgb(unsigned int col, float *r, float *g, float *b);
 
 /***************** Conversion from RGB ********************/
 
-void rgb_to_yuv(float r, float g, float b, float *ly, float *lu, float *lv);
+void rgb_to_yuv(float r, float g, float b, float *ly, float *lu, float *lv, int colorspace);
 void rgb_to_ycc(float r, float g, float b, float *ly, float *lcb, float *lcr, int colorspace);
 void rgb_to_hsv(float r, float g, float b, float *lh, float *ls, float *lv);
 void rgb_to_hsv_v(const float rgb[3], float r_hsv[3]);
@@ -164,4 +168,3 @@ void lift_gamma_gain_to_asc_cdl(float *lift, float *gamma, float *gain, float *o
 #endif
 
 #endif /* __BLI_MATH_COLOR_H__ */
-
diff --git a/source/blender/blenlib/intern/math_color.c b/source/blender/blenlib/intern/math_color.c
index 6d7d24c79c3..a091595bc6c 100644
--- a/source/blender/blenlib/intern/math_color.c
+++ b/source/blender/blenlib/intern/math_color.c
@@ -83,24 +83,45 @@ void hsl_to_rgb_v(const float hsl[3], float r_rgb[3])
 	hsl_to_rgb(hsl[0], hsl[1], hsl[2], &r_rgb[0], &r_rgb[1], &r_rgb[2]);
 }
 
-void rgb_to_yuv(float r, float g, float b, float *ly, float *lu, float *lv)
+void rgb_to_yuv(float r, float g, float b, float *ly, float *lu, float *lv, int colorspace)
 {
 	float y, u, v;
-	y = 0.299f * r + 0.587f * g + 0.114f * b;
-	u = -0.147f * r - 0.289f * g + 0.436f * b;
-	v = 0.615f * r - 0.515f * g - 0.100f * b;
+
+	switch (colorspace) {
+		case BLI_YUV_ITU_BT601:
+			y = 0.299f * r + 0.587f * g + 0.114f * b;
+			u = -0.147f * r - 0.289f * g + 0.436f * b;
+			v = 0.615f * r - 0.515f * g - 0.100f * b;
+			break;
+		case BLI_YUV_ITU_BT709:
+		default:
+			y = 0.2126f * r + 0.7152f * g + 0.0722f * b;
+			u = -0.09991f * r - 0.33609f * g + 0.436f * b;
+			v = 0.615f * r - 0.55861f * g - 0.05639f * b;
+			break;
+	}
 
 	*ly = y;
 	*lu = u;
 	*lv = v;
 }
 
-void yuv_to_rgb(float y, float u, float v, float *lr, float *lg, float *lb)
+void yuv_to_rgb(float y, float u, float v, float *lr, float *lg, float *lb, int colorspace)
 {
 	float r, g, b;
-	r = y + 1.140f * v;
-	g = y - 0.394f * u - 0.581f * v;
-	b = y + 2.032f * u;
+
+	switch (colorspace) {
+		case BLI_YUV_ITU_BT601:
+			r = y + 1.140f * v;
+			g = y - 0.394f * u - 0.581f * v;
+			b = y + 2.032f * u;
+			break;
+		case BLI_YUV_ITU_BT709:
+			r = y + 1.28033f * v;
+			g = y - 0.21482f * u - 0.38059f * v;
+			b = y + 2.12798f * u;
+			break;
+	}
 
 	*lr = r;
 	*lg = g;