fix [#27746] Black and White Render doesn't work and/or Saves as a Blank screen

convert to grayscale when saving renders rather then only writing the red channel.

2 files changed, 6 insertions, 0 deletions

diff --git a/source/blender/blenlib/BLI_math_color.h b/source/blender/blenlib/BLI_math_color.h
index fe09706cb3d..a6a1238a064 100644
--- a/source/blender/blenlib/BLI_math_color.h
+++ b/source/blender/blenlib/BLI_math_color.h
@@ -70,6 +70,7 @@ unsigned int rgb_to_cpack(float r, float g, float b);
 unsigned int hsv_to_cpack(float h, float s, float v);
 
 float rgb_to_grayscale(float rgb[3]);
+unsigned char rgb_to_grayscale_byte(unsigned char rgb[3]);
 
 /***************** Profile Transformations ********************/
 
diff --git a/source/blender/blenlib/intern/math_color.c b/source/blender/blenlib/intern/math_color.c
index ef1d5da56d8..93143eb7db3 100644
--- a/source/blender/blenlib/intern/math_color.c
+++ b/source/blender/blenlib/intern/math_color.c
@@ -488,6 +488,11 @@ float rgb_to_grayscale(float rgb[3])
 	return 0.3f*rgb[0] + 0.58f*rgb[1] + 0.12f*rgb[2];
 }
 
+unsigned char rgb_to_grayscale_byte(unsigned char rgb[3])
+{
+	return (76*(unsigned short)rgb[0] + 148*(unsigned short)rgb[1] + 31*(unsigned short)rgb[2]) / 255;
+}
+
 /* ********************************* lift/gamma/gain / ASC-CDL conversion ********************************* */
 
 void lift_gamma_gain_to_asc_cdl(float *lift, float *gamma, float *gain, float *offset, float *slope, float *power)