A simple projector using PyCUDA: the SimplePyCUDAProjector module

class nnfbp.SimplePyCUDAProjector.SimplePyCUDAProjector(recSize, angles)

Bases: object

Implementation of the projector interface using PyCUDA and pyfft.

A projector needs to implement:

• Forward projecting
• Back projecting
• Creating a FBP reconstruction with a custom filter

You can use this class as an abstracted weight matrix \(W\): multiplying an instance proj of this class by an image results in a forward projection of the image, and multiplying proj.T by a sinogram results in a backprojection of the sinogram:

proj = SimplePyCUDAProjector(...)
fp = proj*image
bp = proj.T*sinogram

Parameters:

• recSize (int) – Width/height of the reconstruction volume. (only 2D squares are supported)
• angles (numpy.ndarray) – Array with angles in radians.

backProject(sinogram=None, returnResult=True, clipCircle=False, singleAngle=None)

Backproject a sinogram.

Parameters:

• sinogram (numpy.ndarray) – The sinogram data. If None, use existing data on the GPU.
• returnResult (bool) – Whether to return the result as a numpy.ndarray, or simply keep in on the GPU.
• clipCircle (bool) – Whether to only reconstruct the unit disk.
• singleAngle (int) – Only reconstruct using this angle. None if you want to reconstruct normally, using all angles.

Returns:

numpy.ndarray – The backprojection.

calcNextPowerOfTwo(val)

Calculated the power of two larger than val. Used internally.

filterSinogram(filt, sinogram)

Filter a sinogram sino with filter filt. Used internally.

forwProject(image=None, returnResult=True)

Forward project an image.

Parameters:

• image (numpy.ndarray) – The image data. If None, use existing data on the GPU.
• returnResult (bool) – Whether to return the result as a numpy.ndarray, or simply keep in on the GPU.

Returns:

numpy.ndarray – The forward projection.

reconstructWithFilter(sinogram, filt, clipCircle=False, returnResult=True)

Create a FBP reconstruction of the sinogram with a custom filter

Parameters:

• sinogram (numpy.ndarray) – The sinogram data
• filt (numpy.ndarray) – 1D custom filter

Returns:

numpy.ndarray – The reconstruction.

class nnfbp.SimplePyCUDAProjector.SimplePyCUDAProjectorTranspose(parentProj)

Implements the proj.T functionality.

Do not use directly, since it can be accessed as member .T of an SimplePyCUDAProjector object.