Phase-only correlation function by means of Hartley Transform

In image processing or pattern recognition, Fourier Transform is widely used for frequency-domain analysis. In particular, the Phase Only Correlation (POC) method demonstrates high robustness and accuracy in the pattern matching and the image registration. However, there is a disadvantage in required memory machine because of the calculation of 2D-FFT. In this case, Hartley transform can be a very good substitute for more commonly used Fourier transform when the real input data are concerned. The Hartley transform is similar to the Fourier transform, but it is free from the need to process complex numbers. It also has some distinctive features that make it an interesting choice when a greater efficiency in memory requirements is needed. In this paper we show the correspondence between the Phase-Only Correlation (POC) function obtained by means of FFT and by FHT.