CosineBellWindow

class photutils.psf_matching.CosineBellWindow(alpha)

Bases: SplitCosineBellWindow

Class to define a 2D cosine bell window function.

This window equals 1.0 only at the exact center point and smoothly tapers to 0.0. The taper begins immediately from the center (no inner plateau) and extends outward over a fraction alpha of the maximum radius.

Use this window when you want to preserve the very center of an image while applying a gentle taper that starts relatively far from the edges. It provides less artifact suppression than TukeyWindow for the same alpha value because the taper region is positioned differently.

Parameters:

alphafloat, optional

The percentage of array values that are tapered. Must be between 0.0 and 1.0, inclusive. When alpha=1, this becomes a HanningWindow.

Notes

Equivalent to SplitCosineBellWindow(alpha=alpha, beta=0.0).

Examples

import matplotlib.pyplot as plt
from photutils.psf_matching import CosineBellWindow

taper = CosineBellWindow(alpha=0.3)
data = taper((101, 101))
fig, ax = plt.subplots()
axim = ax.imshow(data, origin='lower')
fig.colorbar(axim)

(Source code, png, hires.png, pdf, svg)

A 1D cut across the image center:

import matplotlib.pyplot as plt
from photutils.psf_matching import CosineBellWindow

taper = CosineBellWindow(alpha=0.3)
data = taper((101, 101))
fig, ax = plt.subplots()
ax.plot(data[50, :])

(Source code, png, hires.png, pdf, svg)

Methods Summary

__call__(shape)

Generate the window function for the given shape.

Methods Documentation

__call__(shape)

Generate the window function for the given shape.

Parameters:

shapetuple of int

The size of the output array along each axis.

Returns:

result2D ndarray

The window function as a 2D array.