openpiv_cxx.process.fft_correlate_images

openpiv_cxx.process.fft_correlate_images(image_a, image_b, window_size=32, overlap=16, correlation_method='circular', thread_count=1)

Standard FFT based cross-correlation of two images.

Parameters:

  • frame_a (ndarray) – A two dimensionional array containing grey levels of the first frame.

  • frame_b (ndarray) – A two dimensionional array containing grey levels of the second frame.

  • window_size (int) – The size of the (square) interrogation window, [default: 32 pix].

  • overlap (int) – The number of pixels by which two adjacent windows overlap, [default: 16 pix].

  • correlation_method (str) – Which correlation method to use where ‘circular’ is periodic (e.g. not padded) and ‘linear’ is padded to size 2*window_size.

  • thread_count (int) – The number of threads to use with values < 1 automatically setting thread_count to the maximum of concurrent threads - 1, [default: 1].

Returns:

corr – A three dimensional array with axis 0 being the two dimensional correlation matrix of an interrogation window.

Return type:

ndarray