A simple projector using the CPU: the SimpleCPUProjector module

class nnfbp.SimpleCPUProjector.Projector(recSize, angles)

Bases: object

Implementation of the projector interface using the CPU.

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 = Projector(...)
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(sino)

Backproject a sinogram.

Parameters:sinogram (numpy.ndarray) – The sinogram data Returns:numpy.ndarray – The backprojection.

calcNextPowerOfTwo(val)

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

filterSinogram(filt, sino)

Filter a sinogram sino with filter filt. Used internally.

forwProject(image)

Forward project an image.

Parameters:image (numpy.ndarray) – The image data. Returns:numpy.ndarray – The forward projection.

reconstructWithFilter(sinogram, filt)

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.SimpleCPUProjector.ProjectorTranspose(parentProj)

Implements the proj.T functionality.

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