Hi Andrew, A thought: is there a way to set the parameters for the sine gratings such as to produce a simple black and white grating? (ie. black for 6 pixels, white for six pixels, black for 6 pixels, white for six pixels, etc.) Thanks! Mark ====================================== The Vision Egg mailing list Archives: //www.freelists.org/archives/visionegg Website: http://www.visionegg.org/mailinglist.html