mirror of
https://github.com/c-sooyoung/fold_slice.git
synced 2026-09-17 17:29:09 +09:00
115 lines
4.6 KiB
Matlab
115 lines
4.6 KiB
Matlab
% IMSHIFT_FFT will apply shift with subpixel accuracy that can be different for each frame.
|
||
%
|
||
% img = imshift_fft(img, x,y, apply_fft = true, weights = [])
|
||
%
|
||
% Inputs:
|
||
% **img - input image stack, can be complex valued
|
||
% **x, y - shifts in number of pixels
|
||
% **apply_fft , if false, then images will be assumed to be in fourier space
|
||
% **weights - 0<W<=1 apply importance weighting to avoid noise in low reliability regions
|
||
% returns:
|
||
% ++img - shifted image stack
|
||
|
||
%*-----------------------------------------------------------------------*
|
||
%| |
|
||
%| 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 = imshift_fft(img, x,y, apply_fft, weights)
|
||
|
||
|
||
if nargin < 3
|
||
y = x(:,2); % x can be either Nx1 or Nx2 vector
|
||
x = x(:,1);
|
||
end
|
||
if nargin < 4
|
||
apply_fft = true; % if false, assume that img is already fft transformed
|
||
end
|
||
if nargin < 5
|
||
weights = []; % weights prevents amplitifaction of noise in low reliability regions
|
||
end
|
||
if ~isempty(weights) && ~isscalar(weights)
|
||
eps_ = 1e2*eps(ones(1,'like',img));
|
||
weights = max(eps_, weights); % avoid dividing by zero
|
||
end
|
||
|
||
if all(x==0) && all(y==0)
|
||
return
|
||
end
|
||
|
||
if ~isempty(weights) && ~isscalar(weights) && apply_fft
|
||
img = img .* weights;
|
||
end
|
||
|
||
if all(x==0) % shift only along one axis -> faster
|
||
img = utils.imshift_fft_ax(img, y,1, apply_fft);
|
||
elseif all(y==0)
|
||
img = utils.imshift_fft_ax(img, x,2, apply_fft);
|
||
else
|
||
%% 2D FFT SHIFTING
|
||
real_img = isreal(img);
|
||
Np = size(img);
|
||
|
||
|
||
if apply_fft
|
||
img = math.fft2_partial(img);
|
||
end
|
||
|
||
xgrid = ifftshift(-fix(Np(2)/2):ceil(Np(2)/2)-1)/Np(2);
|
||
X = reshape((x(:)*xgrid)',1,Np(2),[]);
|
||
X = exp((-2i*pi)*X);
|
||
img = bsxfun(@times, img,X);
|
||
ygrid = ifftshift(-fix(Np(1)/2):ceil(Np(1)/2)-1)/Np(1);
|
||
Y = reshape((y(:)*ygrid)',Np(1),1,[]);
|
||
Y = exp((-2i*pi)*Y);
|
||
img = bsxfun(@times, img,Y);
|
||
|
||
if apply_fft
|
||
img = math.ifft2_partial(img);
|
||
end
|
||
if real_img
|
||
img = real(img);
|
||
end
|
||
end
|
||
|
||
|
||
if ~isempty(weights) && ~isscalar(weights) && apply_fft
|
||
weights = utils.imshift_fft(weights, x,y); %% weights needs to be shifted as well
|
||
img = img ./ weights;
|
||
end
|
||
|
||
|
||
end
|