gdImageGrayScale 4794 gd/gd.c        	if (gdImageGrayScale(im_src) == 1) {
gdImageGrayScale  656 gd/libgd/gd.h  int gdImageGrayScale(gdImagePtr src);
gdImageGrayScale   24 gd/libgd/gd_compat.h int gdImageGrayScale(gdImagePtr src);