openpiv.pyprocess.correlate_windows

static pyprocess.correlate_windows(window_a, window_b, corr_method='fft', nfftx=None, nffty=None)

Compute correlation function between two interrogation windows.

Use the correlation theorem to speed up the computation of the correlation function.

Parameters :

window_a : 2d np.ndarray

a two dimensions array for the first interrogation window

window_b : 2d np.ndarray

a two dimensions array for the second interrogation window

corr_method : string

one of the two methods currently implemented: ‘fft’ or ‘direct’

nfftx : int

a size of the 2D FFT in x-direction, [default: 2 x windows_a.shape[0] is recommended]

nffty : int

a size of the 2D FFT in y-direction, [default: 2 x windows_a.shape[1] is recommended]

Returns :

corr : 2d np.ndarray

a two dimensions array with the correlation function