put_3bytes        270 wrgif.c        	  put_3bytes(dinfo, GETJSAMPLE(colormap[0][i]) >> cshift);
put_3bytes        274 wrgif.c        	put_3bytes(dinfo, (i * 255 + (num_colors-1)/2) / (num_colors-1));
put_3bytes        278 wrgif.c              put_3bytes(dinfo, 0);