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81 lines
3.3 KiB
Matlab
81 lines
3.3 KiB
Matlab
% INTERPOLATEFT_3D Computes 3D interpolated image using Fourier transform, i.e. dirichlet
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% interpolation. Computes the FT and then adjusts the size by zero padding
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% or cropping then it computes the IFT. A real valued input may have
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% residual imaginary components, which is given by numerical precision of
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% the FT and IFT.
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%
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% imout = interpolateFT_3D(im,outsize, fourier_mask)
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%
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% Inputs
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% **im - Input real/complex 3D volume
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% **outsize - Output size of array [ny nx nz]
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% **fourier_mask - if provided, apply mask in fourier space. ifftn( mask * fftn(im))
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% *returns*
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% ++imout - Output real/complex 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 [ imout ] = interpolateFT_3D(im,outsize, fourier_mask)
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Nout = outsize;
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Nin = size(im);
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if all(Nout == Nin) && nargin < 3
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imout = im;
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return
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end
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imFT = fftshift(fftn(im));
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imout = utils.crop_pad_3D(imFT, outsize);
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if nargin > 2
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% if provided, apply fourier mask, NOT FFTSHIFTED !!
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imout = imout .* fourier_mask;
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end
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imout = ifftn(ifftshift(imout))*(Nout(1)*Nout(2)*Nout(3)/(Nin(1)*Nin(2)*Nin(3)));
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if isreal(im)
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imout = real(imout);
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end
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