fg_al            4140 ext/gd/gd.c    	int fg_al, bg_al, al;
fg_al            4178 ext/gd/gd.c    	fg_al = gdImageAlpha(bg_img, _fg);
fg_al            4189 ext/gd/gd.c    		al = bg_al + (double) (fg_al - bg_al) / aa_steps * (i + 1);