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106 lines
3.7 KiB
Matlab
106 lines
3.7 KiB
Matlab
% IMSHIFT_FFT_AX will apply subpixel shift that can be different for each
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% frame along one dimension only
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% If apply_fft == false, then images will be assumed to be in fourier space
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%
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% Inputs:
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% **img - inputs ndim array to be shifted along ax-th dimension
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% **ax - axis along which the array will be shifted
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% **shift - Nx1 vector of shifts, positive direction is up
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% **apply_fft = false - if the img is already after fft, default is false
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% *returns*:
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% ++img - shifted image / volume
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%*-----------------------------------------------------------------------*
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%| |
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%| Except where otherwise noted, this work is licensed under a |
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%| Creative Commons Attribution-NonCommercial-ShareAlike 4.0 |
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%| International (CC BY-NC-SA 4.0) license. |
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%| |
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%| Copyright (c) 2017 by Paul Scherrer Institute (http://www.psi.ch) |
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%| |
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%| Author: CXS group, PSI |
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%*-----------------------------------------------------------------------*
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% You may use this code with the following provisions:
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%
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% If the code is fully or partially redistributed, or rewritten in another
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% computing language this notice should be included in the redistribution.
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%
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% If this code, or subfunctions or parts of it, is used for research in a
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% publication or if it is fully or partially rewritten for another
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% computing language the authors and institution should be acknowledged
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% in written form in the publication: “Data processing was carried out
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% using the “cSAXS matlab package” developed by the CXS group,
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% Paul Scherrer Institut, Switzerland.”
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% Variations on the latter text can be incorporated upon discussion with
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% the CXS group if needed to more specifically reflect the use of the package
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% for the published work.
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%
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% A publication that focuses on describing features, or parameters, that
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% are already existing in the code should be first discussed with the
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% authors.
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%
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% This code and subroutines are part of a continuous development, they
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% are provided “as they are” without guarantees or liability on part
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% of PSI or the authors. It is the user responsibility to ensure its
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% proper use and the correctness of the results.
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function img = imshift_fft_ax(img, shift, ax, apply_fft)
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if nargin < 4
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apply_fft = true;
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end
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if all(shift == 0)
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return
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end
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isReal = isreal(img);
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Npix = size(img);
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if ndims(img) == 3
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Np = [1,1,Npix(3)];
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else
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Np = Npix;
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Np(ax) = 1;
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end
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Ng = ones(1,3);
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if ax > ndims(img)
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Npix(ax) = 1;
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end
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Ng(ax) = Npix(ax);
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if isscalar(shift)
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shift = shift .* ones(Np);
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end
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grid = ifftshift(-fix(Npix(ax)/2):ceil(Npix(ax)/2)-1)/Npix(ax);
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X = bsxfun(@times, reshape(shift,Np), reshape(grid,Ng));
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X = exp((-2i*pi)*X);
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if apply_fft
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img = math.fft_partial(img, ax, 1+mod(ax, ndims(img)) );
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end
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img = bsxfun(@times, img,X);
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if apply_fft
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img = math.ifft_partial(img, ax, 1+mod(ax, ndims(img)) );
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end
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if isReal
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img = real(img);
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end
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end
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