JWST POPPY:docs

measure_strehl

poppy.measure_strehl(HDUlist_or_filename=None, ext=0, slice=0, center=None, display=True, verbose=True, cache_perfect=False)[source]

Estimate the Strehl ratio for a PSF.

This requires computing a simulated PSF with the same properties as the one under analysis.

Note that this calculation will not be very accurate unless both PSFs are well sampled, preferably several times better than Nyquist. See Roberts et al. 2004 SPIE 5490 for a discussion of the various possible pitfalls when calculating Strehl ratios.

Parameters:

HDUlist_or_filename : string

Either a fits.HDUList object or a filename of a FITS file on disk

ext : int

Extension in that FITS file

slice : int, optional

If that extension is a 3D datacube, which slice (plane) of that datacube to use

center : tuple

center to compute around. Default is image center. If the center is on the crosshairs between four pixels, then the mean of those four pixels is used. Otherwise, if the center is in a single pixel, then that pixel is used.

print_, display : bool

control whether to print the results or display plots on screen.

cache_perfect : bool

use caching for perfect images? greatly speeds up multiple calcs w/ same config

Returns:

strehl : float

Strehl ratio as a floating point number between 0.0 - 1.0

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