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117 lines
8.8 KiB
Matlab
117 lines
8.8 KiB
Matlab
% ACCELERATE_GRADIENTS use the Nesterov's Accelerated Gradient method
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%
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% cache = accelerate_gradients(self, par, cache, iter)
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%
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% ** self structure containing inputs: e.g. current reconstruction results, data, mask, positions, pixel size, ..
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% ** par structure containing parameters for the engines
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% ** cache structure with precalculated values to avoid unnecessary overhead
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% ** iter number of the current iteration
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%
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% returns:
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% ** self updated structure containing inputs
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% ** cache structure with precalculated values - stores the previous accelerated gradients updates
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%
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% Academic License Agreement
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%
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% Source Code
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%
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% Introduction
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% • This license agreement sets forth the terms and conditions under which the PAUL SCHERRER INSTITUT (PSI), CH-5232 Villigen-PSI, Switzerland (hereafter "LICENSOR")
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% will grant you (hereafter "LICENSEE") a royalty-free, non-exclusive license for academic, non-commercial purposes only (hereafter "LICENSE") to use the cSAXS
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% ptychography MATLAB package computer software program and associated documentation furnished hereunder (hereafter "PROGRAM").
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%
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% Terms and Conditions of the LICENSE
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% 1. LICENSOR grants to LICENSEE a royalty-free, non-exclusive license to use the PROGRAM for academic, non-commercial purposes, upon the terms and conditions
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% hereinafter set out and until termination of this license as set forth below.
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% 2. LICENSEE acknowledges that the PROGRAM is a research tool still in the development stage. The PROGRAM is provided without any related services, improvements
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% or warranties from LICENSOR and that the LICENSE is entered into in order to enable others to utilize the PROGRAM in their academic activities. It is the
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% LICENSEE’s responsibility to ensure its proper use and the correctness of the results.”
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% 3. THE PROGRAM IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR
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% A PARTICULAR PURPOSE AND NONINFRINGEMENT OF ANY PATENTS, COPYRIGHTS, TRADEMARKS OR OTHER RIGHTS. IN NO EVENT SHALL THE LICENSOR, THE AUTHORS OR THE COPYRIGHT
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% HOLDERS BE LIABLE FOR ANY CLAIM, DIRECT, INDIRECT OR CONSEQUENTIAL DAMAGES OR OTHER LIABILITY ARISING FROM, OUT OF OR IN CONNECTION WITH THE PROGRAM OR THE USE
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% OF THE PROGRAM OR OTHER DEALINGS IN THE PROGRAM.
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% 4. LICENSEE agrees that it will use the PROGRAM and any modifications, improvements, or derivatives of PROGRAM that LICENSEE may create (collectively,
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% "IMPROVEMENTS") solely for academic, non-commercial purposes and that any copy of PROGRAM or derivatives thereof shall be distributed only under the same
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% license as PROGRAM. The terms "academic, non-commercial", as used in this Agreement, mean academic or other scholarly research which (a) is not undertaken for
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% profit, or (b) is not intended to produce works, services, or data for commercial use, or (c) is neither conducted, nor funded, by a person or an entity engaged
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% in the commercial use, application or exploitation of works similar to the PROGRAM.
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% 5. LICENSEE agrees that it shall make the following acknowledgement in any publication resulting from the use of the PROGRAM or any translation of the code into
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% another computing language:
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% "Data processing was carried out using the cSAXS ptychography MATLAB package developed by the Science IT and the coherent X-ray scattering (CXS) groups, Paul
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% Scherrer Institut, Switzerland."
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%
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% Additionally, any publication using the package, or any translation of the code into another computing language should cite for difference map:
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% P. Thibault, M. Dierolf, A. Menzel, O. Bunk, C. David, F. Pfeiffer, High-resolution scanning X-ray diffraction microscopy, Science 321, 379–382 (2008).
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% (doi: 10.1126/science.1158573),
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% for mixed coherent modes:
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% P. Thibault and A. Menzel, Reconstructing state mixtures from diffraction measurements, Nature 494, 68–71 (2013). (doi: 10.1038/nature11806),
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% for LSQ-ML method
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% M. Odstrcil, A. Menzel, M.G. Sicairos, Iterative least-squares solver for generalized maximum-likelihood ptychography, Optics Express, 2018
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% for OPRP method
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% M. Odstrcil, P. Baksh, S. A. Boden, R. Card, J. E. Chad, J. G. Frey, W. S. Brocklesby, "Ptychographic coherent diffractive imaging with orthogonal probe relaxation." Optics express 24.8 (2016): 8360-8369
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% and/or for multislice:
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% E. H. R. Tsai, I. Usov, A. Diaz, A. Menzel, and M. Guizar-Sicairos, X-ray ptychography with extended depth of field, Opt. Express 24, 29089–29108 (2016).
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% 6. Except for the above-mentioned acknowledgment, LICENSEE shall not use the PROGRAM title or the names or logos of LICENSOR, nor any adaptation thereof, nor the
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% names of any of its employees or laboratories, in any advertising, promotional or sales material without prior written consent obtained from LICENSOR in each case.
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% 7. Ownership of all rights, including copyright in the PROGRAM and in any material associated therewith, shall at all times remain with LICENSOR, and LICENSEE
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% agrees to preserve same. LICENSEE agrees not to use any portion of the PROGRAM or of any IMPROVEMENTS in any machine-readable form outside the PROGRAM, nor to
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% make any copies except for its internal use, without prior written consent of LICENSOR. LICENSEE agrees to place the following copyright notice on any such copies:
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% © All rights reserved. PAUL SCHERRER INSTITUT, Switzerland, Laboratory for Macromolecules and Bioimaging, 2017.
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% 8. The LICENSE shall not be construed to confer any rights upon LICENSEE by implication or otherwise except as specifically set forth herein.
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% 9. DISCLAIMER: LICENSEE shall be aware that Phase Focus Limited of Sheffield, UK has an international portfolio of patents and pending applications which relate
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% to ptychography and that the PROGRAM may be capable of being used in circumstances which may fall within the claims of one or more of the Phase Focus patents,
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% in particular of patent with international application number PCT/GB2005/001464. The LICENSOR explicitly declares not to indemnify the users of the software
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% in case Phase Focus or any other third party will open a legal action against the LICENSEE due to the use of the program.
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% 10. This Agreement shall be governed by the material laws of Switzerland and any dispute arising out of this Agreement or use of the PROGRAM shall be brought before
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% the courts of Zürich, Switzerland.
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%
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function [self,cache] = accelerate_gradients(self, par, cache, iter)
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%% accelerated gradients extension, tries to look ahead in direction of the last update
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if iter == par.accelerated_gradients_start
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cache.object_prev = {self.object, self.object};
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cache.probe_prev = {self.probe, self.probe};
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for ii = 1:length(cache.illum_sum_0)
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cache.update_weights{ii} = cache.illum_sum_0{ii}.^2 ./ (cache.illum_sum_0{ii}.^2 + 0.1*cache.MAX_ILLUM(ii)^2);
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end
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elseif iter > par.accelerated_gradients_start
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object_start = max(par.object_change_start, par.accelerated_gradients_start);
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probe_start = max(par.probe_change_start, par.accelerated_gradients_start);
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cache.object_prev{1} = cache.object_prev{2};
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cache.object_prev{2} = self.object;
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cache.probe_prev{1} = cache.probe_prev{2};
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cache.probe_prev{2} = self.probe;
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% accelerate the object reconstructions
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if iter > par.object_change_start
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beta = (iter-object_start+1)/(iter-object_start+3);
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for ii = 1:size(self.object,1)
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for layer = 1:size(self.object,2)
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if ii == 1 && utils.verbose() > 3
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plotting.smart_figure(555)
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update = cache.update_weights{ii}.* (self.object{ii,layer} - cache.object_prev{1}{ii,layer});
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plotting.imagesc3D(update)
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title('Acceleration step in the Nesterov method')
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axis xy off
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utils.verbose(0, 'Norm of accelerated gradient = %g', math.norm2(update) )
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drawnow
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end
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self.object{ii,layer} = self.object{ii,layer} + ...
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beta*cache.update_weights{ii}.*(self.object{ii,layer} - cache.object_prev{1}{ii,layer});
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end
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end
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end
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% accelerate only the first OPR mode of the probe
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if iter > par.probe_change_start
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beta = (iter-probe_start+1)/(iter-probe_start+3);
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for ii = 1:numel(self.probe)
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self.probe{ii}(:,:,:,1) = self.probe{ii}(:,:,:,1) + ...
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beta.*(self.probe{ii}(:,:,:,1) - cache.probe_prev{1}{ii}(:,:,:,1));
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end
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end
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end
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end |