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1D and 2D FFT-based convolution functions in Python, using numpy.fft
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from numpy.fft import fft, ifft, fft2, ifft2, fftshift | |
import numpy as np | |
def fft_convolve2d(x,y): | |
""" 2D convolution, using FFT""" | |
fr = fft2(x) | |
fr2 = fft2(np.flipud(np.fliplr(y))) | |
m,n = fr.shape | |
cc = np.real(ifft2(fr*fr2)) | |
cc = np.roll(cc, -m/2+1,axis=0) | |
cc = np.roll(cc, -n/2+1,axis=1) | |
return cc | |
def fft_convolve1d(x,y): #1d cross correlation, fft | |
""" 1D convolution, using FFT """ | |
fr=fft(x) | |
fr2=fft(np.flipud(y)) | |
cc=np.real(ifft(fr*fr2)) | |
return fftshift(cc) | |
if __name__ == "__main__": | |
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