PIV: fft cross-correlation with large searchwindow

Liang

Hi! I am now compiling a PIV code, the problem with my FFT method is that when I use a small interogate window and a larger search window, I padded zeros of int_window in order to make the complex conjugate multiplication of fft of the two matrix. However, a problems occurs that I can substracted the mean of int_window in advance, but how about the demean and normalization factor of the search window? Here, what I am interested is the local mean and deviation of search window, which part would overlap with moving int_window when doing cross-corrleation via fft.

do I make myself understood? please help if you have used the same algorithm.