Blue Green Red (BGR) byte ordering exists in a few image processing libraries "for historical reasons", mostly because it seems to have been a Microsoft standard.
Does anyone know the historical reason?
Color spectrum is almost always read as "Red Green Blue" in English.
I can't think of any byte ordering argument that would favor one over the other. OpenGL and earlier HW graphics tended to be either ARGB or RGBA (iirc). Intel little-endian doesn't seem to make any difference in a 4byte structure
The only blue first reason I can think of is that broadcast uses YUV and U is blue-green and V is red-green.