Optical encoding of color three-dimensional correlation

Three-dimensional (3D) correlation of color images, considering the color distribution as the third dimension, has been shown to be useful for color pattern recognition tasks. Nevertheless, 3D correlation cannot be directly performed on an optical correlator, that can only process two-dimensional (2D) signals. We propose a method to encode 3D functions onto 2D ones in such a way that the Fourier transform and correlation of these signals, that can be optically performed, encode the 3D Fourier transform and correlation of the 3D signals. The theory for the encoding is given and experimental results obtained in an optical correlator are shown. © 2002 Published by Elsevier Science B.V.