tomopy.sim.project

Module for simulation of x-rays.

Functions:

angles(nang[, ang1, ang2])	Return uniformly distributed projection angles in radian.
project(obj, theta[, center, emission, pad, …])	Project x-rays through a given 3D object.
fan_to_para(tomo, dist, geom)	Convert fan-beam data to parallel-beam data.
para_to_fan(tomo, dist, geom)	Convert parallel-beam data to fan-beam data.
add_gaussian(tomo[, mean, std])	Add Gaussian noise.
add_poisson(tomo)	Add Poisson noise.
add_salt_pepper(tomo[, prob, val])	Add salt and pepper noise.
add_focal_spot_blur(tomo, spotsize)	Add focal spot blur.

tomopy.sim.project.angles(nang, ang1=0.0, ang2=180.0)

Return uniformly distributed projection angles in radian.

Parameters:

• nang (int, optional) – Number of projections.
• ang1 (float, optional) – First projection angle in degrees.
• ang2 (float, optional) – Last projection angle in degrees.

Returns:

array – Projection angles

tomopy.sim.project.project(obj, theta, center=None, emission=True, pad=True, sinogram_order=False, ncore=None, nchunk=None)

Project x-rays through a given 3D object.

Parameters:

• obj (ndarray) – Voxelized 3D object.
• theta (array) – Projection angles in radian.
• center (array, optional) – Location of rotation axis.
• emission (bool, optional) – Determines whether output data is emission or transmission type.
• pad (bool, optional) – Determines if the projection image width will be padded or not. If True, then the diagonal length of the object cross-section will be used for the output size of the projection image width.
• sinogram_order (bool, optional) – Determines whether output data is a stack of sinograms (True, y-axis first axis) or a stack of radiographs (False, theta first axis).
• ncore (int, optional) – Number of cores that will be assigned to jobs.
• nchunk (int, optional) – Chunk size for each core.

Returns:

ndarray – 3D tomographic data.

tomopy.sim.project.project2(objx, objy, theta, center=None, emission=True, pad=True, sinogram_order=False, axis=0, ncore=None, nchunk=None)

Project x-rays through a given 3D object.

Parameters:

• objx (ndarray) – (x, y) components of vector of a voxelized 3D object.
• theta (array) – Projection angles in radian.
• center (array, optional) – Location of rotation axis.
• emission (bool, optional) – Determines whether output data is emission or transmission type.
• pad (bool, optional) – Determines if the projection image width will be padded or not. If True, then the diagonal length of the object cross-section will be used for the output size of the projection image width.
• sinogram_order (bool, optional) – Determines whether output data is a stack of sinograms (True, y-axis first axis) or a stack of radiographs (False, theta first axis).
• ncore (int, optional) – Number of cores that will be assigned to jobs.
• nchunk (int, optional) – Chunk size for each core.

Returns:

ndarray – 3D tomographic data.

tomopy.sim.project.project3(objx, objy, objz, theta, center=None, emission=True, pad=True, sinogram_order=False, axis=0, ncore=None, nchunk=None)

Project x-rays through a given 3D object.

Parameters:

• objx (ndarray) – (x, y) components of vector of a voxelized 3D object.
• theta (array) – Projection angles in radian.
• center (array, optional) – Location of rotation axis.
• emission (bool, optional) – Determines whether output data is emission or transmission type.
• pad (bool, optional) – Determines if the projection image width will be padded or not. If True, then the diagonal length of the object cross-section will be used for the output size of the projection image width.
• sinogram_order (bool, optional) – Determines whether output data is a stack of sinograms (True, y-axis first axis) or a stack of radiographs (False, theta first axis).
• ncore (int, optional) – Number of cores that will be assigned to jobs.
• nchunk (int, optional) – Chunk size for each core.

Returns:

ndarray – 3D tomographic data.

tomopy.sim.project.fan_to_para(tomo, dist, geom)

Convert fan-beam data to parallel-beam data.

Warning

Not implemented yet.

Parameters:

• tomo (ndarray) – 3D tomographic data.
• dist (float) – Distance from fan-beam vertex to rotation center.
• geom (str) – Fan beam geometry. ‘arc’ or ‘line’.

Returns:

ndarray – Transformed 3D tomographic data.

tomopy.sim.project.para_to_fan(tomo, dist, geom)

Convert parallel-beam data to fan-beam data.

Warning

Not implemented yet.

Parameters:

• tomo (ndarray) – 3D tomographic data.
• dist (float) – Distance from fan-beam vertex to rotation center.
• geom (str) – Fan beam geometry. ‘arc’ or ‘line’.

Returns:

ndarray – Transformed 3D tomographic data.

tomopy.sim.project.add_gaussian(tomo, mean=0, std=None)

Add Gaussian noise.

Parameters:

• tomo (ndarray) – 3D tomographic data.
• mean (float, optional) – Mean of the Gaussian distribution.
• std (float, optional) – Standard deviation of the Gaussian distribution.

Returns:

ndarray – 3D tomographic data after Gaussian noise added.

tomopy.sim.project.add_poisson(tomo)

Add Poisson noise.

Parameters:tomo (ndarray) – 3D tomographic data. Returns:ndarray – 3D tomographic data after Poisson noise added.

tomopy.sim.project.add_salt_pepper(tomo, prob=0.01, val=None)

Add salt and pepper noise.

Parameters:

• tomo (ndarray) – 3D tomographic data.
• prob (float, optional) – Independent probability that each element of a pixel might be corrupted by the salt and pepper type noise.
• val (float, optional) – Value to be assigned to the corrupted pixels.

Returns:

ndarray – 3D tomographic data after salt and pepper noise added.

tomopy.sim.project.add_focal_spot_blur(tomo, spotsize)

Add focal spot blur.

Warning

Not implemented yet.

Parameters:

• tomo (ndarray) – 3D tomographic data.
• spotsize (float) – Focal spot size of circular x-ray source.