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Added perceptually uniform fire colormap #943

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merged 4 commits into from Oct 21, 2016

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jbednar commented Oct 20, 2016

The "hot" colormap that is the default for Image and other Raster types in Holoviews is highly perceptually nonuniform, which makes strange artifacts and makes it difficult to interpret data:

image

On my request, Peter Kovesi created a much better version he called linear_kryw_0_100_c71 (see http://peterkovesi.com/projects/colourmaps):

image

The new colormap (left) gives much smoother images that more faithfully represent the data:

image

This PR adds the new colormap, renamed "fire" for simplicity and to indicate the similarity to "hot". A subsequent PR should change the default colormap to "fire".

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jlstevens commented Oct 20, 2016

Looks good!

I'm just wondering if the formatting of the triples might look nicer if you aligned all the closing square brackets...

@jlstevens jlstevens added this to the v1.7.0 milestone Oct 20, 2016

jbednar added some commits Oct 20, 2016

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jbednar commented Oct 20, 2016

Ok, reformatted as suggested.

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philippjfr commented Oct 21, 2016

Looks good to me! For now matplotlib colormaps are used everywhere so you'll be able to reference it by name. In future we can decouple matplotlib colormaps from bokeh and switch from hot to fire in our defaults.

@philippjfr philippjfr merged commit 517e481 into master Oct 21, 2016

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@jbednar jbednar deleted the fire branch Oct 21, 2016

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