ZScaleInterval

class astropy.visualization.ZScaleInterval(n_samples=1000, contrast=0.25, max_reject=0.5, min_npixels=5, krej=2.5, max_iterations=5)

Bases: BaseInterval

Interval based on IRAF’s zscale.

https://iraf.net/forum/viewtopic.php?showtopic=134139

Original implementation: https://github.com/spacetelescope/stsci.numdisplay/blob/master/lib/stsci/numdisplay/zscale.py

Licensed under a 3-clause BSD style license (see AURA_LICENSE.rst).

Parameters:

n_samplespython:int, optional

The number of points in the array to sample for determining scaling factors. Defaults to 1000.

Changed in version 5.2: n_samples replaces the deprecated nsamples argument, which will be removed in the future.

contrastpython:float, optional

The scaling factor (between 0 and 1) for determining the minimum and maximum value. Larger values increase the difference between the minimum and maximum values used for display. Defaults to 0.25.

max_rejectpython:float, optional

If more than max_reject * npixels pixels are rejected, then the returned values are the minimum and maximum of the data. Defaults to 0.5.

min_npixelspython:int, optional

If there are less than min_npixels pixels remaining after the pixel rejection, then the returned values are the minimum and maximum of the data. Defaults to 5.

krejpython:float, optional

The number of sigma used for the rejection. Defaults to 2.5.

max_iterationspython:int, optional

The maximum number of iterations for the rejection. Defaults to 5.

Attributes Summary

nsamples

Deprecated since version 5.2.

Methods Summary

get_limits(values)

Return the minimum and maximum value in the interval based on the values provided.

Attributes Documentation

nsamples

Deprecated since version 5.2: The nsamples attribute is deprecated and may be removed in a future version. Use n_samples instead.

Methods Documentation

get_limits(values)

Return the minimum and maximum value in the interval based on the values provided.

Parameters:

valuesndarray

The image values.

Returns:

vmin, vmaxpython:float

The mininium and maximum image value in the interval.