The Litton magnetooptic spatial light modulator has a periodic structure which produces a replicated Fourier transform under coherent illumination. As a result, this modulator is not responsive to edge enhancement by the conventional means of a centered dc blocking spot in the transform plane of a coherent optical processor. Alternative spatial filtering masks for edge enhancement are described, which produce output images having dark edges on a light background as well as masks which produce bright edges on a dark background. Adjustable edge widths can be achieved. Both bright and dark edges can be produced in the same output image. One edge enhancement method requires no spatial filter mask.