PHP Manual . ... PHP 4 >= 4.0.6) ImageCopyMergeGray -- Copy and merge part of an image with gray scale . int ImageCopyMergeGray ( resource dst_im, resource src_im, int dst_x, int dst_y, int src_x, int src_y, int src_w, int src_h, int pct) . ImageCopyMergeGray() copy a part of src_im onto dst_im starting at the x,y coordinates src_x , src_y with a width of src_w and a height of src_h . ... When pct = 0, no action is taken, when 100 this function behaves identically to ImageCopy() . ...