hyperspy.misc.holography.reconstruct module

hyperspy.misc.holography.reconstruct.aperture_function(r, apradius, rsmooth)

A smooth aperture function that decays from apradius-rsmooth to apradius+rsmooth.

Parameters:
  • r (ndarray) – Array of input data (e.g. frequencies)
  • apradius (float) – Radius (center) of the smooth aperture. Decay starts at apradius - rsmooth.
  • rsmooth (float) – Smoothness in halfwidth. rsmooth = 1 will cause a decay from 1 to 0 over 2 pixel.
hyperspy.misc.holography.reconstruct.estimate_sideband_position(holo_data, holo_sampling, central_band_mask_radius=None, sb='lower')

Finds the position of the sideband and returns its position.

Parameters:
  • holo_data (ndarray) – The data of the hologram.
  • holo_sampling (tuple) – The sampling rate in both image directions.
  • central_band_mask_radius (float, optional) – The aperture radius used to mask out the centerband.
  • sb (str, optional) – Chooses which sideband is taken. ‘lower’ or ‘upper’
Returns:
Return type:

Tuple of the sideband position (y, x), referred to the unshifted FFT.
hyperspy.misc.holography.reconstruct.estimate_sideband_size(sb_position, holo_shape, sb_size_ratio=0.5)

Estimates the size of sideband filter

Parameters:
  • holo_shape (array_like) – Holographic data array
  • sb_position (tuple) – The sideband position (y, x), referred to the non-shifted FFT.
  • sb_size_ratio (float, optional) – Size of sideband as a fraction of the distance to central band
Returns:

sb_size – Size of sideband filter
Return type:

float
hyperspy.misc.holography.reconstruct.freq_array(shape, sampling)

Makes up a frequency array.

Parameters:
  • shape (tuple) – The shape of the array.
  • sampling (tuple) – The sampling rates of the array.
Returns:
Return type:

Array of the frequencies.
hyperspy.misc.holography.reconstruct.reconstruct(holo_data, holo_sampling, sb_size, sb_position, sb_smoothness, output_shape=None, plotting=False)

Core function for holographic reconstruction.

Parameters:
  • holo_data (array_like) – Holographic data array
  • holo_sampling (tuple) – Sampling rate of the hologram in y and x direction.
  • sb_size (float) – Size of the sideband filter in pixel.
  • sb_position (tuple) – Sideband position in pixel.
  • sb_smoothness (float) – Smoothness of the aperture in pixel.
  • output_shape (tuple, optional) – New output shape.
  • plotting (boolean) – Plots the masked sideband used for reconstruction.
Returns:

wav – Reconstructed electron wave
Return type:

nparray