Illumination sensitivity of joint transform correlators using differential processing: computer simulation and experimental studies

Differential and binary differential joint-transform correlators are found to be associated with high tolerance to illumination variation of the reference and target. This makes them suitable for illumination-independent pattern recognition applications. Computer simulation results show that a tolerance limit as high as an amplitude ratio of 0.25 between the target and the reference image can be attained. As a refinement to the above mentioned techniques, we suggest the use of isotropic difference operators. We also present some experimental results For the differential type JTCs. (C) 1998 Elsevier Science B.V.