ZScaleInterval#
- class astropy.visualization.ZScaleInterval(n_samples=1000, contrast=0.25, max_reject=0.5, min_npixels=5, krej=2.5, max_iterations=5)[source]#
Bases:
BaseInterval
Interval based on IRAF’s zscale.
Original implementation: spacetelescope/stsci.numdisplay
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 7.0:
nsamples
parameter is removed.- contrast
python:float
, optional The scaling factor (between 0 and 1) for determining the minimum and maximum value. Larger values decrease 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.
- n_samples
Methods Summary
__call__
(values[, clip, out])Transform values using this interval.
get_limits
(values)Return the minimum and maximum value in the interval based on the values provided.
Methods Documentation
- __call__(values, clip=True, out=None)#
Transform values using this interval.
The
vmin
andvmax
values are determined by theget_limits
method.The following transformation is then applied to the values:
\[{\rm result} = \frac{{\rm values} - v_{\rm min}} {v_{\rm max} - v_{\rm min}}\]If
clip
isTrue
(default), the result is then clipped to the [0:1] range.- Parameters:
- valuesnumpy:array_like
The input values.
- clipbool, optional
If
True
(default), values outside the [0:1] range are clipped to the [0:1] range.- out
ndarray
, optional If specified, the output values will be placed in this array (typically used for in-place calculations).
- Returns:
- result
ndarray
The transformed values.
- result