int ImageCopyMerge (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)
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. The portion defined will be copied onto the x,y coordinates, dst_x and dst_y. The two images will be merged according to pct which can range from 0 to 100. When pct = 0, no action is taken, when 100 this function behaves identically to ImageCopy().
Note: This function was added in PHP 4.0.6