Abstract : We described a joint transform correlator (JTC) that used multiple input images encoded in the spatial domain. This allowed various combinations of cross correlations between input images to be performed. We extended the theory of a JTC to multiple inputs, and provided experimental results for four inputs with an optically-addressed spatial light modulator in the Fourier plane. We proposed a system to perform multiwavelet feature extraction. For multiwavelet scales, the output consisted of 4m-1 correlation results, one of which is the desired result. Using conventional optics, the space and bandwidth product for wavelet feature extraction can be made the same as for a two input joint-transform correlator.