Another interesting type of image processing that involves a special type of image intensity filtering is edge enhancement. In this configuration, the image of an object is recorded and then read out in a conventional two-beam coupling geometry. However, depending on the ratio between the signal (or object) and reference beam intensities (Is0/Ir0), either an exact replica of the object (left, Is0/Ir0 = 0.1) or an edge-enhanced image (right, Is0/Ir0 =20) are obtained.H. Ono et al., Appl. Phys. Lett. 79, 895 (2001)