colormap_hess#

gammapy.visualization.colormap_hess(transition=0.5, width=0.1)[source]#

Colormap often used in H.E.S.S. collaboration publications.

This colormap goes black -> blue -> red -> yellow -> white.

A sharp blue -> red -> yellow transition is often used for significance images with a value of red at transition ~ 5 or transition ~ 7 so that the following effect is achieved:

  • black, blue: non-significant features, not well visible

  • red: features at the detection threshold transition

  • yellow, white: significant features, very well visible

The transition parameter is defined between 0 and 1. To calculate the value from data units an ImageNormalize instance should be used (see example below).

Parameters
transitionfloat

Value of the transition to red (between 0 and 1). Default is 0.5.

widthfloat

Width of the blue-red color transition (between 0 and 1). Default is 0.5.

Returns
colormapmatplotlib.colors.LinearSegmentedColormap

Colormap.

Examples

>>> from gammapy.visualization import colormap_hess
>>> from astropy.visualization.mpl_normalize import ImageNormalize
>>> from astropy.visualization import LinearStretch
>>> normalize = ImageNormalize(vmin=-5, vmax=15, stretch=LinearStretch())
>>> transition = normalize(5)
>>> cmap = colormap_hess(transition=transition)