PowerStretch

class astropy.visualization.PowerStretch(a)

Bases: BaseStretch

A power stretch.

The stretch is given by:

\[y = x^a\]

Parameters:

afloat

The power index (see the above formula). a must be greater than 0.

Attributes Summary

inverse	A stretch object that performs the inverse operation.
power	Deprecated since version 6.0.

Methods Summary

__call__(values[, clip, out, invalid])

Transform values using this stretch.

Attributes Documentation

inverse

A stretch object that performs the inverse operation.

power

Deprecated since version 6.0: The power attribute is deprecated and may be removed in a future version. Use a instead.

Methods Documentation

__call__(values, clip=True, out=None, invalid=None)

Transform values using this stretch.

Parameters:

valuesarray_like

The input values, which should already be normalized to the [0:1] range.

clipbool, optional

If True (default), values outside the [0:1] range are clipped to the [0:1] range.

outndarray, optional

If specified, the output values will be placed in this array (typically used for in-place calculations).

invalidNone or float, optional

Value to assign NaN values generated by this class. NaNs in the input values array are not changed. This option is generally used with matplotlib normalization classes, where the invalid value should map to the matplotlib colormap “under” value (i.e., any finite value < 0). If None, then NaN values are not replaced. This keyword has no effect if clip=True.

Returns:

resultndarray

The transformed values.