We describe some basic optical image-processing operations with acousto-optic ͑AO͒ Bragg diffraction. Instead of using frequency-plane filters, we place an AO cell behind the object. We then realize experimentally one-dimensional edge enhancement, which utilizes a high-pass filtering effect in the undiffracted order from the AO cell. A numerical simulation compares well with the experimental results. With two AO cells oriented orthogonally to each other, a second-order mixed derivative operation, evident from the four-corner enhancement of a square, is also demonstrated.

Basic real-time programmable image-processing operations are accomplished by use of acousto-optic ͑AO͒ cells. Instead of frequency-plane filters, the AO cells are placed directly behind the object. The onedimensional edge-enhancement results with one AO cell can be improved by use of two AO cells that are placed in tandem with contrapropagating sound. The dominant second-derivative operation obtained from the transfer function of the undiffracted order works like a one-dimensional Laplacian operator that enables improved edge enhancement.

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