dftups¶
- image_registration.fft_tools.dftups(inp, nor=None, noc=None, usfac=1, roff=0, coff=0)[source]¶
Translated from matlab:
Manuel Guizar - Dec 13, 2007
Modified from dftus, by J.R. Fienup 7/31/06
Upsampled DFT by matrix multiplies, can compute an upsampled DFT in just a small region.
This code is intended to provide the same result as if the following operations were performed:
Embed the array “in” in an array that is usfac times larger in each dimension. ifftshift to bring the center of the image to (1,1).
Take the FFT of the larger array
Extract an [nor, noc] region of the result. Starting with the [roff+1 coff+1] element.
It achieves this result by computing the DFT in the output array without the need to zeropad. Much faster and memory efficient than the zero-padded FFT approach if [nor noc] are much smaller than [nr*usfac nc*usfac]
- Parameters:
- usfacint
Upsampling factor (default usfac = 1)
- nor,nocint,int
Number of pixels in the output upsampled DFT, in units of upsampled pixels (default = size(in))
- roff, coffint, int
Row and column offsets, allow to shift the output array to a region of interest on the DFT (default = 0)