Function stbi__compute_y_16

include/stb/stb_image.h:1803–1806

// nothing
#else
static stbi__uint16 stbi__compute_y_16(int r, int g, int b)
{
   return (stbi__uint16) (((r*77) + (g*150) +  (29*b)) >> 8);
}
#endif

#if defined(STBI_NO_PNG) && defined(STBI_NO_PSD)