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109 lines
4.6 KiB
Matlab
109 lines
4.6 KiB
Matlab
% UNWRAP2D_FFT2 simple and very fast 2D phase unwrapping based on FT
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% integration of DIC signal (phase gradient)
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%
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% [phase, residues] = unwrap2D_fft2(img, empty_region=[], step=0, weights=[], polyfit_order=1)
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%
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% Inputs:
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% **img - either complex valued image or real valued phase gradient
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% *optional*
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% **empty_region - 2x1 or 1x1 vector, size of empty region assumed around edges for phase offset removal
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% **step - used to calculate finite difference gradient, 0 = analytical (default) expression
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% **polyfit_order -1 = dont assume anything about the removed phase,
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% subtract linear offset from each horizontal line separatelly
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% 0 = assume that removed degree of freedom is only a constant offset
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% 1 = assume that removed degree of freedom is a 2D plane
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% *returns*:
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% ++phase - unwrapped phase with subtracted phase ramp / offset
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% ++residues - calculated binary map of phase residuas
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%
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% See also: utils.findresidues, utils.remove_sinogram_ramp
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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 [phase, residues] = unwrap2D_fft2(img, empty_region, step, weights, polyfit_order)
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import utils.*
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import math.*
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if isreal(img)
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error('Complex-valued input array was expected')
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end
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if nargin < 3 || isempty(step)
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step = 0; % use analytical method
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end
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if nargin < 4 || isempty(weights)
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weights = 1;
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end
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if nargin < 5
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polyfit_order = 1; % subtract 2D plane
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end
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weights = max(0, min(1, single(weights))); % weights are assumed in range [0,1]
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img = weights .* img ./ (abs(img)+eps);
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clear weights
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padding = [64,64]; % padding to avoid periodic boundary artefacts
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if any(padding > 0)
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img = padarray(img,padding,'symmetric','both');
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img = smooth_edges(img, 5, [1,2]);
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end
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[dX,dY] = get_phase_gradient_2D(img, step, 0);
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clear img
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phase = real(get_img_int_2D(dX,dY));
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if any(padding > 0)
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% remove padding
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ind = {padding(1):size(phase,1)-padding(1)-1,padding(2):size(phase,2)-padding(2)-1, ':'};
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phase = phase(ind{:});
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end
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if exist('empty_region', 'var') && ~isempty(empty_region)
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phase = remove_sinogram_ramp(phase,empty_region, polyfit_order);
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end
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if nargout > 1
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residues = abs(findresidues(img)) > 0.1;
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end
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end
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