double alpha_max= alpha_mean + thresh;
for (i=0; i<3; i++)
MUST( alpha_min <= alpha[i] && alpha[i] <= alpha_max,
+ MP(p);
MRGB(here);MRGB(background);MRGB(foreground);MI(fg_extra);
MF(alpha_min); MI(i);MF(alpha[i]);MF(alpha_max) );
+ if ( -1e-5 < alpha_mean && alpha_mean <= 0.0 ) alpha_mean= 0.0;
+ if (1.0 <= alpha_mean && alpha_mean <= 1.0+1e-5) alpha_mean= 1.0;
+
MUST( 0 <= alpha_mean &&
- (fg_extra ? alpha_mean < 0.999 : alpha_mean >= 1.0),
+ (fg_extra ? (alpha_mean < 0.999) : (alpha_mean <= 1.0)),
+ MP(p);
MRGB(here);MRGB(background);MRGB(foreground);MI(fg_extra);
MF(alpha_mean); MF(alpha[0]);MF(alpha[1]);MF(alpha[2]); );