#define ALPHA_DIFFERENCE STD_ALPHA
#define COLOR_DIFFERENCE(mx, Sc, Sa, Dc, Da) (STD_BLEND(mx,Sc,Sa,Dc,Da) + \
(mabs(Sc * Da - Dc * Sa) / mx))
#define ALPHA_DIFFERENCE STD_ALPHA
#define COLOR_DIFFERENCE(mx, Sc, Sa, Dc, Da) (STD_BLEND(mx,Sc,Sa,Dc,Da) + \
(mabs(Sc * Da - Dc * Sa) / mx))