COSINE WAVE ENCODED JOINT TRANSFORM CORRELATION

A cosine wave encoded joint transform correlation is proposed that can deliver excellent correlation performance in the presence of nonoverl apping noise or additive noise, and guarantee that the optical gain is less than unity-facilitating implementation. The method proposed uses three CCDs to capture the power spectra of the joint image, the refer ence-only image, and the input scene, and then extracts the cosine wav e information of the joint power spectrum using simple subtraction and division operations. The extracted cosine wave information is encoded onto the input SLM of the second optical setup, resulting in a high o ptical efficiency. The cosine wave encoded joint transform correlation is found to be similar to even-function correlations between the phas e-only Fourier-plane information of the reference and input images, wh ich resembles the correlation of the phase-only input scene informatio n with the phase-only filter using a reference image in the VanderLugt correlation arrangement. Computer simulations show that the cosine wa ve encoded joint transform correlation outperforms binary joint transf orm correlation when the targets are embedded in either nonoverlapping noise or scenes with additive noise; performance is maintained ever! when the target has a very low light contrast ratio in a severely nois e-corrupted input scene. (C) 1996 Society of Photo-Optical Instrumenta tion Engineers.