#define SF_COLOR_ILUM_GREEN 19969L
The SF_COLOR_ILUM_[component] define the fixed point luminance vector values for red, green, and blue. To convert colors into black and white, the balance red, green, and blue fixed point coefficient of 10112, 19969, and 2687, respectively, is used. Here, The Green luminance fixed point vector value 19969 is used.
The standard NTSC weights of 9798, 19235, 3735 are NOT used, as they are only applicable to RGB colors in a gamma 2.2 color space.
The fixed point values must be divided by 32768 to produce the correct result.
Render_Color.h