Cosine wave encoded joint transform correlation

Abstract

University of SussexIndustrial Informatics & ManufacturingSystems Research CentreSchool of Engineering, ENGG1Brighton, United Kingdom BN1 9QTAbstract. A cosine wave encoded joint transform correlation is pro-posed that can deliver excellent correlation performance in the presenceof nonoverlapping noise or additive noise, and guarantee that the opticalgain is less than unity—facilitating implementation. The method pro-posed uses three CCDs to capture the power spectra of the joint image,the reference-only image, and the input scene, and then extracts thecosine wave information of the joint power spectrum using simple sub-traction and division operations. The extracted cosine wave informationis encoded onto the input SLM of the second optical setup, resulting in ahigh optical efficiency. The cosine wave encoded joint transform corre-lation is found to be similar to even-function correlations between thephase-only Fourier-plane information of the reference and input images,which resembles the correlation of the phase-only input scene informa-tion with the phase-only filter using a reference image in the VanderLugtcorrelation arrangement. Computer simulations show that the cosinewave encoded joint transform correlation outperforms binary joint trans-form correlation when the targets are embedded in either nonoverlap-ping noise or scenes with additive noise; performance is maintainedeven when the target has a very low light contrast ratio in a severelynoise-corrupted input scene. © 1996 Society of Photo-Optical Instru-mentation Engineers.