% -----------------------------------------------------------------------
% This file is part of the ASTRA Toolbox
% 
% Copyright: 2010-2021, imec Vision Lab, University of Antwerp
%            2014-2021, CWI, Amsterdam
% License: Open Source under GPLv3
% Contact: astra@astra-toolbox.com
% Website: http://www.astra-toolbox.com/
% -----------------------------------------------------------------------

vol_geom = astra_create_vol_geom(256, 256);
proj_geom = astra_create_proj_geom('parallel', 1.0, 384, linspace2(0,pi,180));

% For CPU-based algorithms, a "projector" object specifies the projection
% model used. In this case, we use the "strip" model.
proj_id = astra_create_projector('strip', proj_geom, vol_geom);

% Create a sinogram from a phantom
P = phantom(256);
[sinogram_id, sinogram] = astra_create_sino(P, proj_id);
figure(1); imshow(P, []);
figure(2); imshow(sinogram, []);

astra_mex_data2d('delete', sinogram_id);

% We now re-create the sinogram data object as we would do when loading
% an external sinogram
sinogram_id = astra_mex_data2d('create', '-sino', proj_geom, sinogram);

% Create a data object for the reconstruction
rec_id = astra_mex_data2d('create', '-vol', vol_geom);

% Set up the parameters for a reconstruction algorithm using the CPU
% The main difference with the configuration of a GPU algorithm is the
% extra ProjectorId setting.
cfg = astra_struct('SIRT');
cfg.ReconstructionDataId = rec_id;
cfg.ProjectionDataId = sinogram_id;
cfg.ProjectorId = proj_id;

% Available algorithms:
% ART, SART, SIRT, CGLS, FBP


% Create the algorithm object from the configuration structure
alg_id = astra_mex_algorithm('create', cfg);

% Run 20 iterations of the algorithm
% This will have a runtime in the order of 10 seconds.
astra_mex_algorithm('iterate', alg_id, 20);

% Get the result
rec = astra_mex_data2d('get', rec_id);
figure(3); imshow(rec, []);

% Clean up. 
astra_mex_projector('delete', proj_id);
astra_mex_algorithm('delete', alg_id);
astra_mex_data2d('delete', rec_id);
astra_mex_data2d('delete', sinogram_id);