Transforms

The Transform holds all the forward, inverse and adjoint transforms between an image space and some other (e.g. Fourier) space. Users should use this class to wrap their own transformations to ensure they work with the forward.ForwardOperator and mcmc.PxMCMC classes. The SphericalWaveletTransform class is an example.

class transforms.Transform

Base class to wrap transformations.

forward()

e.g. spherical image to spherical harmonics. Implemented by user in custom child class.

inverse()

e.g. spherical harmonics to spherical image. Implemented by user in custom child class.

forward_adjoint()

e.g. spherical harmonics to spherical image. Implemented by user in custom child class.

inverse_adjoint()

e.g. spherical image to spherical harmonics. Implemented by user in custom child class.

class transforms.IdentityTransform

Identity transform i.e. does nothing

class transforms.SphericalWaveletTransform(L, B, J_min, dirs=1, spin=0, harmonic=False)

Spherical wavelet transforms

Parameters
  • L (int) – angular bandlimit

  • B (float) – wavelet scale parameter

  • J_min (int) – minimum wavelet scale

  • dirs (int) – azimuthal bandlimit for directional wavelets

  • spin (int) – spin number of spherical signal

  • harmonic (bool) – inputs and outputs in spherical harmonic space

forward(X)

Transform image to spherical wavelet space.

Parameters

X – spherical image as a 1D array

Returns

1D array of spherical wavelet coefficients

inverse(X)

Transform spherical wavelet to image space.

Parameters

X – 1D array of spherical wavelet coefficients

Returns

spherical image as a 1D array

inverse_adjoint(X)

Adjoint transform image to spherical wavelet space.

Parameters

X – spherical image as a 1D array

Returns

1D array of spherical wavelet coefficients

forward_adjoint(X)

Transform spherical wavelet to image space.

Parameters

X – 1D array of spherical wavelet coefficients

Returns

spherical image as a 1D array