Update version to 1.3

1 files changed, 45 insertions, 0 deletions

diff --git a/samples/s009_projection_matrix.m b/samples/s009_projection_matrix.m
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+%------------------------------------------------------------------------
+% This file is part of the
+% All Scale Tomographic Reconstruction Antwerp Toolbox ("ASTRA-Toolbox")
+%
+% Copyright: iMinds-Vision Lab, University of Antwerp
+% License: Open Source under GPLv3
+% Contact: mailto:astra@ua.ac.be
+% Website: http://astra.ua.ac.be
+%------------------------------------------------------------------------
+
+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);
+
+% Generate the projection matrix for this projection model.
+% This creates a matrix W where entry w_{i,j} corresponds to the
+% contribution of volume element j to detector element i.
+matrix_id = astra_mex_projector('matrix', proj_id);
+
+% Get the projection matrix as a Matlab sparse matrix.
+W = astra_mex_matrix('get', matrix_id);
+
+
+% Manually use this projection matrix to do a projection:
+P = phantom(256)';
+s = W * P(:);
+s = reshape(s, [proj_geom.DetectorCount size(proj_geom.ProjectionAngles, 2)])';
+figure(1), imshow(s,[]);
+
+% Because Matlab's matrices are stored transposed in memory compared to C++,
+% reshaping them to a vector doesn't give the right ordering for multiplication
+% with W. We have to take the transpose of the input and output to get the same
+% results (up to numerical noise) as using the toolbox directly.
+
+% Each row of the projection matrix corresponds to a detector element.
+% Detector t for angle p is for row 1 + t + p*proj_geom.DetectorCount.
+% Each column corresponds to a volume pixel.
+% Pixel (x,y) corresponds to column 1 + x + y*vol_geom.GridColCount.
+
+
+astra_mex_projector('delete', proj_id);
+astra_mex_matrix('delete', matrix_id);