make_sigmoid_mask

make_sigmoid_mask#

ptyrad.utils.math_ops.make_sigmoid_mask(Npix, relative_radius=0.6666666666666666, relative_width=0.2, center=None)[source]#

Create a 2D circular mask with a sigmoid transition.

Parameters:

  • Npix (int) – Size of the square mask (Npix x Npix).

  • relative_radius (float) – Relative radius of the circular mask where the sigmoid equals 0.5, as a fraction of the image size.

  • relative_width (float) – Relative width of the sigmoid transition, as a fraction of the image size.

  • center (Optional[Tuple[float, float]]) – (y, x) coordinates of the center of the circle. Defaults to the center of the image.

Returns:

A 2D circular mask with a sigmoid transition.

Return type:

torch.Tensor

Notes

  • The default relative_radius=2/3 is inspired by its use in abTEM to reduce edge artifacts in diffraction patterns. It sets an antialias cutoff frequency at 2/3 of the simulated kMax. https://abtem.readthedocs.io/en/latest/user_guide/appendix/antialiasing.html

  • The relative_width controls the steepness of the sigmoid transition. Smaller values result in sharper transitions, while larger values produce smoother transitions.

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