fg_bl            4139 ext/gd/gd.c    	int rd, gr, bl, fg_rd, fg_gr, fg_bl, bg_rd, bg_gr, bg_bl;
fg_bl            4177 ext/gd/gd.c    	fg_bl = gdImageBlue (bg_img, _fg);
fg_bl            4188 ext/gd/gd.c    		bl = bg_bl + (double) (fg_bl - bg_bl) / aa_steps * (i + 1);