mirror of
https://github.com/c-sooyoung/fold_slice.git
synced 2026-09-17 23:39:08 +09:00
84 lines
3.6 KiB
Matlab
84 lines
3.6 KiB
Matlab
% IMRESCALE_FFT subpixel precision rescaling based on multiplication by a
|
||
% matrix of fourier transformation, fast only for small arrays
|
||
% Inputs:
|
||
% **img - 2D or stack of 2D images
|
||
% **scale - scaling factor
|
||
% *returns*:
|
||
% ++img - 2D or stack of 2D images scaled by factor scale
|
||
|
||
%*-----------------------------------------------------------------------*
|
||
%| |
|
||
%| Except where otherwise noted, this work is licensed under a |
|
||
%| Creative Commons Attribution-NonCommercial-ShareAlike 4.0 |
|
||
%| International (CC BY-NC-SA 4.0) license. |
|
||
%| |
|
||
%| Copyright (c) 2017 by Paul Scherrer Institute (http://www.psi.ch) |
|
||
%| |
|
||
%| Author: CXS group, PSI |
|
||
%*-----------------------------------------------------------------------*
|
||
% You may use this code with the following provisions:
|
||
%
|
||
% If the code is fully or partially redistributed, or rewritten in another
|
||
% computing language this notice should be included in the redistribution.
|
||
%
|
||
% If this code, or subfunctions or parts of it, is used for research in a
|
||
% publication or if it is fully or partially rewritten for another
|
||
% computing language the authors and institution should be acknowledged
|
||
% in written form in the publication: “Data processing was carried out
|
||
% using the “cSAXS matlab package” developed by the CXS group,
|
||
% Paul Scherrer Institut, Switzerland.”
|
||
% Variations on the latter text can be incorporated upon discussion with
|
||
% the CXS group if needed to more specifically reflect the use of the package
|
||
% for the published work.
|
||
%
|
||
% A publication that focuses on describing features, or parameters, that
|
||
% are already existing in the code should be first discussed with the
|
||
% authors.
|
||
%
|
||
% This code and subroutines are part of a continuous development, they
|
||
% are provided “as they are” without guarantees or liability on part
|
||
% of PSI or the authors. It is the user responsibility to ensure its
|
||
% proper use and the correctness of the results.
|
||
|
||
|
||
|
||
function img_rescale = imrescale_fft(img, scale)
|
||
|
||
if scale == 1 || isnan(scale)
|
||
img_rescale = img;
|
||
return
|
||
end
|
||
|
||
|
||
N = size(img);
|
||
|
||
for i = 1:2
|
||
if N(1) ~= N(2) || i == 1
|
||
ind_x = real(zeros(N(i),1, 'like', img));
|
||
ind_x(:) = (0:N(i)-1)/N(i)-0.5;
|
||
grid = ind_x*ind_x';
|
||
grid = -2i*pi*N(i)/scale*grid;
|
||
W{i} = exp(grid)'/N(i); % matrix of fourier transformation
|
||
else
|
||
W{2} = W{1};
|
||
end
|
||
end
|
||
|
||
fimg = fftshift(fft2(fftshift(img)));
|
||
|
||
if size(img,3) > 1
|
||
fimg2 = W{1}*reshape(fimg,N(1),[]);
|
||
fimg2 = reshape(fimg2, N(1),N(2),[]);
|
||
fimg2 = permute(fimg2, [2,1,3]);
|
||
fimg2 = reshape(fimg2, N(2),[]);
|
||
img_rescale = (W{1}*fimg2); % rescale and fft back
|
||
img_rescale = reshape(img_rescale, N(2),N(1),[]);
|
||
img_rescale = permute(img_rescale, [2,1,3]);
|
||
else
|
||
fimg2 = W{1}*fimg;
|
||
img_rescale = (W{2}*fimg2.').';
|
||
end
|
||
|
||
end
|
||
|