Application of unnormalized and phase correlation techniques on infrared images

Abstract

Accurate and unambiguous measurement of relative displacement between two images is important in a large number of practical applications. Comparison of a real-time captured image with a stored reference image is one such example. Comparison of two sensed images acquired within a short and accurately known time interval can be used to measure the velocity to height ratio of a moving imaging system. Accurate superposition of two images acquired at different times and their consequent, point by point subtraction, calls for attention to changes which have occurred over time in the real-time scenario. All such applications require measurement of the displacement vector to accuracies within a small fraction of pixel. The phase correlation method is based on the fact that most of the information about the relative displacement vector is contained in the phase of their cross-power spectrum.