Abstract
Color image recognition by optical correlation techniques is an attractive topic since most real objects consist of spectral as well as shape information. Previous work on color image correlation has been carried out by Shi,1 Ishii and Murata,2 and Yu and Chao.3 All this work was based on coherent optical processing and therefore suffers from the stringent alignment requirements of the spatial filter. To overcome this difficulty, Mu et al.4 introduced an incoherent technique using a Fresnel holographic filter (FHP) to obtain color image correlation. However, most spatial light modulators have monochrome displays and so cannot be applied to the real-time input of a color image. Recently Yu et al.5 used a color liquid crystal television (LCTV) in a coherent optical correlator, but the spatial phase variations of the LCTV severely disrupted coherent optical processing. In this paper we employ a color LCTV in an incoherent correlator with a multiwavelength FHF to achieve real-time input. It has the advantages of no color crosstalk, much relaxed alignment requirements for the spatial filter, and that the spatial phase variation of the LCTV has no influence at all.
© 1992 Optical Society of America
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