BP_CUDA
This is a GPU implementation of a simple backprojection algorithm for 2D data sets. It takes projection data as input, and returns the backprojection of this data.
Supported geometries: parallel, parallel_vec, fanflat, fanflat_vec.
Configuration options
Name |
Description |
|---|---|
ProjectionDataId |
|
ReconstructionDataId |
ID of data object to store the result. The content of this data is overwritten. |
option.PixelSuperSampling |
Each pixel in the volume will be subdivided by this factor along each dimension. This should only be used if pixels in the volume are larger than the detector elements (default: 1). |
option.GPUindex |
The index of the GPU to use (default: 0). |
Example
import astra
import matplotlib.pyplot as plt
import numpy as np
# Create geometries and projector
N = 256
N_ANGLES = 180
det_spacing = 1.0
angles = np.linspace(0, np.pi, N_ANGLES)
proj_geom = astra.create_proj_geom('parallel', det_spacing, N, angles)
vol_geom = astra.create_vol_geom(N, N)
projector_id = astra.create_projector('cuda', proj_geom, vol_geom)
# Generate phantom image
phantom_id, phantom = astra.data2d.shepp_logan(vol_geom)
# Create forward projection
sinogram_id, sinogram = astra.create_sino(phantom_id, projector_id)
# Calculate backprojection
backprojection_id = astra.data2d.create('-vol', vol_geom)
cfg = astra.astra_dict('BP_CUDA')
cfg['ProjectionDataId'] = sinogram_id
cfg['ReconstructionDataId'] = backprojection_id
algorithm_id = astra.algorithm.create(cfg)
astra.algorithm.run(algorithm_id)
backprojection = astra.data2d.get(backprojection_id)
plt.imshow(backprojection, cmap='gray')
# Clean up
astra.data2d.delete([sinogram_id, backprojection_id, phantom_id])
astra.projector.delete(projector_id)
astra.algorithm.delete(algorithm_id)
%% Create phantom
N = 256;
phantom = phantom(N);
%% Create geometries and projector
det_spacing = 1.0;
N_ANGLES = 180;
angles = linspace(0, pi, N_ANGLES);
proj_geom = astra_create_proj_geom('parallel', det_spacing, N, angles);
vol_geom = astra_create_vol_geom(N, N);
projector_id = astra_create_projector('cuda', proj_geom, vol_geom);
%% Create forward projection
[sinogram_id, sinogram] = astra_create_sino(phantom, projector_id);
%% Calculate backprojection
backprojection_id = astra_mex_data2d('create', '-vol', vol_geom);
cfg = astra_struct('BP_CUDA');
cfg.ProjectionDataId = sinogram_id;
cfg.ReconstructionDataId = backprojection_id;
algorithm_id = astra_mex_algorithm('create', cfg);
astra_mex_algorithm('run', algorithm_id);
backprojection = astra_mex_data2d('get', backprojection_id);
imshow(backprojection, []);
%% Clean up
astra_mex_data2d('delete', sinogram_id, backprojection_id);
astra_mex_projector('delete', projector_id);
astra_mex_algorithm('delete', algorithm_id);