Additional functions: the functions module

Additional functions for PyAstraToolbox.

astra.functions.add_noise_to_sino(sinogram_in, I0, seed=None)[source]

Adds Poisson noise to a sinogram.

Parameters:

  • sinogram_in (numpy.ndarray) – Sinogram to add noise to.

  • I0 (float) – Background intensity. Lower values lead to higher noise.

Returns:

numpy.ndarray – the sinogram with added noise.

astra.functions.clear()[source]

Clears all used memory of the ASTRA Toolbox.

Note

This is irreversible.

astra.functions.data_op(op, data, scalar, gpu_core, mask=None)[source]

Perform data operation on data.

Parameters:

  • op – Operation to perform.

  • data – Data to perform operation on.

  • scalar – Scalar argument to data operation.

  • gpu_core – GPU core to perform operation on.

  • mask – Optional mask.

astra.functions.geom_2vec(proj_geom)[source]

Returns a vector-based projection geometry from a basic projection geometry.

Parameters:

proj_geom (dict) – Projection geometry to convert

astra.functions.geom_postalignment(proj_geom, factor)[source]

Apply a postalignment to a vector-based projection geometry. Can be used to model the rotation axis offset.

For 2D geometries, the argument factor is a single float specifying the distance to shift the detector (measured in detector pixels).

For 3D geometries, factor can be a pair of floats specifying the horizontal resp. vertical distances to shift the detector. If only a single float is specified, this is treated as a horizontal shift.

Parameters:

  • proj_geom (dict) – input projection geometry

  • factor (float) – number of pixels to shift the detector

astra.functions.geom_size(geom, dim=None)[source]

Returns the size of a volume or sinogram, based on the projection or volume geometry.

Parameters:

  • geom – Geometry to calculate size from

  • dim (int) – Optional axis index to return

astra.functions.move_vol_geom(geom, pos, is_relative=False)[source]

Moves center of volume geometry to new position.

Parameters:

  • geom (dict) – Input volume geometry

  • pos (tuple) – Tuple (x,y[,z]) for new position, with the center of the image at (0,0[,0])

  • is_relative (bool) – Whether new position is relative to the old position

Returns:

dict – Volume geometry with the new center