poppy.measure_strehl(HDUlist_or_filename=None, ext=0, center=None, display=True, print_=True, cache_perfect=False)[source] [edit on github]

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, ext : string, int

Same as above

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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