def get_distortion_residuals(self, mask_radius, spread):
"""Obtain residuals for experimental data and distortion corrected data
with respect to a simulated symmetric ring pattern.
Parameters
----------
mask_radius : int
Radius, in pixels, for a mask over the direct beam disc.
spread : float
Gaussian spread of each ring in the simulated pattern.
Returns
-------
diff_init : ElectronDiffraction2D
Difference between experimental data and simulated symmetric ring
pattern.
diff_end : ElectronDiffraction2D
Difference between distortion corrected data and simulated symmetric
ring pattern.
"""
# Check all required parameters are defined as attributes
if self.diffraction_pattern is None:
raise ValueError(
"This method requires an Au X-grating diffraction "
"pattern to be provided. Please update the "
"CalibrationDataLibrary.")
if self.affine_matrix is None:
raise ValueError(
"This method requires a distortion matrix to have "
"been determined. Use get_elliptical_distortion "
"to determine this matrix.")
# Set name for experimental data pattern
dpeg = self.diffraction_pattern
ringP = self.ring_params
size = dpeg.data.shape[0]
dpref = generate_ring_pattern(
image_size=size,
mask=True,
mask_radius=mask_radius,
scale=ringP[0],
amplitude=ringP[1],
spread=spread,
direct_beam_amplitude=ringP[3],
asymmetry=1,
rotation=ringP[5],
)
# Apply distortion corrections to experimental data
dpegs = stack_method([dpeg, dpeg, dpeg, dpeg])
dpegs = ElectronDiffraction2D(dpegs.data.reshape((2, 2, size, size)))
dpegs.apply_affine_transformation(self.affine_matrix,
preserve_range=True,
inplace=True)
# Calculate residuals to be returned
diff_init = ElectronDiffraction2D(dpeg.data - dpref.data)
diff_end = ElectronDiffraction2D(dpegs.inav[0, 0].data - dpref.data)
residuals = stack_method([diff_init, diff_end])
return ElectronDiffraction2D(residuals)
def ring_pattern(input_parameters):
x0 = input_parameters
ring_data = generate_ring_pattern(
image_size=256,
mask=True,
mask_radius=10,
scale=x0[0],
amplitude=x0[1],
spread=x0[2],
direct_beam_amplitude=x0[3],
asymmetry=x0[4],
rotation=x0[5],
)
return ElectronDiffraction2D(ring_data)
def test_generate_ring_pattern(input_parameters, known_values, reference_indices):
x0 = input_parameters
rings = generate_ring_pattern(
image_size=256,
mask=True,
mask_radius=10,
scale=x0[0],
amplitude=x0[1],
spread=x0[2],
direct_beam_amplitude=x0[3],
asymmetry=x0[4],
rotation=x0[5],
)
assert np.allclose(
known_values, rings[reference_indices[:, 0], reference_indices[:, 1]]
)