diff options
Diffstat (limited to 'samples/python')
| -rw-r--r-- | samples/python/s022_fbp_cor.py | 98 |
1 files changed, 98 insertions, 0 deletions
diff --git a/samples/python/s022_fbp_cor.py b/samples/python/s022_fbp_cor.py new file mode 100644 index 0000000..eb2f56b --- /dev/null +++ b/samples/python/s022_fbp_cor.py @@ -0,0 +1,98 @@ +# ----------------------------------------------------------------------- +# Copyright: 2010-2016, iMinds-Vision Lab, University of Antwerp +# 2013-2016, CWI, Amsterdam +# +# Contact: astra@uantwerpen.be +# Website: http://www.astra-toolbox.com/ +# +# This file is part of the ASTRA Toolbox. +# +# +# The ASTRA Toolbox is free software: you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation, either version 3 of the License, or +# (at your option) any later version. +# +# The ASTRA Toolbox is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with the ASTRA Toolbox. If not, see <http://www.gnu.org/licenses/>. +# +# ----------------------------------------------------------------------- + +import astra +import numpy as np + +cor_shift = 3.6 + +vol_geom = astra.create_vol_geom(256, 256) +proj_geom = astra.create_proj_geom('parallel', 1.0, 256, np.linspace(0,np.pi,180,False)) + +# Projection geometry with shifted center of rotation +# We create this by shifting the detector center V[:,2:4] by a multiple of the detector +# orientation V[:,4:6]. +proj_geom_cor = astra.functions.geom_2vec(proj_geom) +V = proj_geom_cor['Vectors'] +V[:,2:4] = V[:,2:4] + cor_shift * V[:,4:6] + +# As before, create a sinogram from a phantom, using the shifted center of rotation +import scipy.io +P = scipy.io.loadmat('phantom.mat')['phantom256'] + +proj_id_cor = astra.create_projector('cuda',proj_geom_cor,vol_geom) +sinogram_id, sinogram = astra.create_sino(P, proj_id_cor) + +# Change the projection geometry metadata attached to the sinogram to standard geometry, +# and try to do a reconstruction, to show the misalignment artifacts caused by +# the shifted center of rotation +astra.data2d.change_geometry(sinogram_id, proj_geom) + +import pylab +pylab.gray() +pylab.figure(1) +pylab.imshow(P) +pylab.figure(2) +pylab.imshow(sinogram) + +# Create a data object for the reconstruction +rec_id = astra.data2d.create('-vol', vol_geom) + +# Set up the parameters for a reconstruction algorithm using the GPU +cfg = astra.astra_dict('FBP_CUDA') +cfg['ReconstructionDataId'] = rec_id +cfg['ProjectionDataId'] = sinogram_id +alg_id = astra.algorithm.create(cfg) +astra.algorithm.run(alg_id) + +# Get the result +rec = astra.data2d.get(rec_id) +pylab.figure(3) +pylab.imshow(rec) + +astra.algorithm.delete(alg_id) +astra.data2d.delete(rec_id) + +# Now change back to the proper, shifted geometry, and do another reconstruction +astra.data2d.change_geometry(sinogram_id, proj_geom_cor) +rec_id = astra.data2d.create('-vol', vol_geom) +cfg = astra.astra_dict('FBP_CUDA') +cfg['ReconstructionDataId'] = rec_id +cfg['ProjectionDataId'] = sinogram_id +alg_id = astra.algorithm.create(cfg) +astra.algorithm.run(alg_id) + +# Get the result +rec = astra.data2d.get(rec_id) +pylab.figure(4) +pylab.imshow(rec) +pylab.show() + + + +astra.data2d.delete(sinogram_id) +astra.projector.delete(proj_id_cor) +astra.algorithm.delete(alg_id) +astra.data2d.delete(rec_id) |