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 (default = 0.5): Value of the transition to red (between 0 and 1).
widthfloat (default = 0.5): Width of the blue-red color transition (between 0 and 1).

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)