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91 lines
3.7 KiB
Matlab
91 lines
3.7 KiB
Matlab
%PROP2FOCUS propagate img to focus
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% prop2focus uses 'phase detection autofocus' to find the focus
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%
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% img... complex-valued object
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% lam... wavelength
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% dx... pixel size
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%
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% optional parameters
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% d_start... initial guess of propagation distance to focus
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% fov... crop to fov and apodize edges
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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 [ d, img_prop ] = prop2focus(img, lam, dx, varargin)
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import utils.*
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img_sz = size(img);
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% defaults
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fov = img_sz(1)*0.6;
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d_start = 0;
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% parse the variable input arguments vararg = cell(0,0);
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for ind = 1:2:length(varargin)
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name = varargin{ind};
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value = varargin{ind+1};
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switch lower(name)
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case 'd_start'
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d_start = value;
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case 'fov'
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fov = value;
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otherwise
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error('Unknown parameter %s', name)
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end
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end
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% prepare fov mask with apodization
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fov_mask = fftshift(fract_hanning_pad(img_sz, round(fov*1.2), round(fov)));
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img = img.*fov_mask;
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% create masks for autofocus
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mask = fract_hanning_pad(img_sz,round(img_sz(1)/5),round(img_sz(1)/5*0.9));
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mask1 = abs(shiftpp2(fftshift(mask),round(img_sz(1)/20),0));
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mask2 = abs(shiftpp2(fftshift(mask),-round(img_sz(1)/20),0));
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% minimize difference between the 2 images
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fun = @(d)sum(sum(abs(abs(fft2(ifftshift(fftshift(fft2(prop_free_nf(img,lam,d,dx))).*mask2)))-(abs(fft2(ifftshift(fftshift(fft2(prop_free_nf(img,lam,d,dx))).*mask1)))))));
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d = fminsearch(fun,d_start);
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% propagate to focus
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img_prop = prop_free_nf(img, lam, d, dx);
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end
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