So, if you need to convert BGR (as $00BBGGRR) color to RGB (as $00RRGGBB) you can extract individual bytes of color and combine it. But let's do it without additional variables, as brain training.
Var 1: assembler
BSWAP - that's almost what we need. This command swap $AABBCCDD to $DDCCBBAA, later we can shift bytes right.
mov eax,AABBCC
bswap eax ; EAX = CCBBAA00