Optical computations of cosine transforms

Utilizing the symmetrical properties of cosine transform, a coherent optical Fourier transform system has been modified to compute cosine transforms optically. The modification involves creating a symmetrical pattern at the input. Cosine transform is known to be useful for data compression and image coding especially when the image space-bandwidth product is finite. It is also attractive even when the image size becomes large but is not statistically stationary; in such case it should be processed in (M × M) stationary blocks of finite size.