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- ZScaleInterval

# 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_samples `python: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.

    contrast `python: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_reject `python: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_npixels `python: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.

    krej `python:float`, optional

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

    max_iterations `python: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:
      values `ndarray`

        The image values.

    Returns:
      vmin, vmax `python:float`

        The mininium and maximum image value in the interval.