If you find this work useful please cite
Peter Kovesi. Good Colour Maps: How to Design Them.
arXiv:1509.03700 [cs.GR] 2015

Summary

This website presents a collection of colour maps that have been designed to have uniform perceptual contrast over their whole range.

Many colour maps provided by vendors have highly uneven perceptual contrast over their range. Colour maps may have points of locally high colour contrast leading to the perception of false anomalies in your data when there is none. Conversely colour maps may also have 'flat spots' of low perceptual contrast that prevent you from seeing features in the data.

To illustrate this the colour maps shown below are rendered on a test image consisting of a sine wave superimposed on a ramp function. The amplitude of the sine wave is modulated from its full value at the top of the image to 0 at the bottom.

What we are hoping to see is the sine wave uniformly visible across the image from left to right. We also want the contrast level, the distance down the image, at which the sine wave remains discernible to be uniform across the image. At the very bottom of the image, where the sine wave amplitude is 0, we just have a linear ramp which simply reproduces the colour map. Given that the underlying data is a featureless ramp we should not perceive any identifiable features across the bottom of the image.

At the top row of the test image the sine wave amplitude from peak to trough is 10% of the total data range. It is not unusual for the sine wave pattern to completely disappear in parts of some vendor colour maps. On the other hand the perceptually uniform colour maps exhibit no false features and the sine wave pattern is uniformly visible across the full width of the test image.

More Information

• The test image: Information about the colour map test image including links to download it in various formats.
• Theory behind the construction of these colour maps.
• Software: MATLAB code that was used to generate and analyse these colour maps.
• User Guide

Note the colour maps presented here are intended for the display of data that varies over a continuous range. For data sets containing a limited set of categorical values it is suggested that you refer to the work by Cynthia Brewer at www.colorbrewer2.org

Download

These colour maps are released under the Creative Commons BY License. A summary of the conditions can be found here. Basically, you are free to use these colour maps in anyway you wish as long as you give appropriate credit.

If you find this work useful please cite:
Peter Kovesi. Good Colour Maps: How to Design Them.
arXiv:1509.03700 [cs.GR] 2015

It seems my new hobby is collecting colour map formats! Let me know of any other formats I should generate. This XKCD Cartoon seems to apply here.

Please note that I have not been able to test all these file formats as I do not have access to all these packages. If you encounter any problems please let me know. Any other feedback you might have would also be appreciated.

Acknowledgments

This work was supported by the Centre for Exploration Targeting, School of Earth Sciences at The University of Western Australia.

I am indebted to Tom Horrocks for his help in generating the ArcGIS style file.

Organisation of the Colour Maps

The colour maps are organised according to the attributes: Linear, Diverging, Rainbow, Cyclic, and Isoluminant.

Linear colour maps are intended for general use and have colour lightness values that increase or decrease linearly over the colour map's range.

Diverging colour maps are suitable where the data being displayed has a well defined reference value and we are interested in differentiating values that lie above, or below, the reference value. The centre point of the colour map will be white, black or grey. It should be noted that, in general, diverging colour maps have a small perceptual flat spot at the centre. The exception being linear-diverging maps which avoid this problem.

Rainbow colour maps are widely used but often misused. It is suggested that they be avoided because they have reversals in the lightness gradient at yellow and red which can upset a viewer's perceptual ordering of the colours in the colour map. However, they are attractive and perhaps can have a legitimate use where the main aim is to differentiate data values rather than communicate a data ordering. I believe the two rainbow colour maps presented here have minimal badness though they do have localised perceptual flat spots at yellow and red.

Cyclic colour maps have colours that are matched at each end. They are intended for the presentation of data that is cyclic such as orientation values or angular phase data. They require particular care in their design (the standard colour circle is not a good map).

Isoluminant colour maps are constructed from colours of equal perceptual lightness. These colour maps are designed for use with relief shading. On their own these colour maps are not very useful because features in the data are very hard to discern. However, when used in conjunction with relief shading their constant lightness means that the colour map does not induce an independent shading pattern that will interfere with, or even hide, the structures induced by the relief shading. The relief shading provides the structural information and the colours provide the data classification information.

Colour Blind colour maps. These are not designed to be merely 'colour blind safe'. These maps have been constructed to lie within either the 2D model of protanopic/deuteranopic colour space, or the 2D model of tritanopic colour space. Hopefully by working within these colour spaces people who are colour blind will be able to share a common perceptual interpretation of data with those who have normal colour vision. It also ensures maximal use of the available colour spaces, and allows chroma and lightness to be properly used in the design of colour maps. I would value any feedback on the usefulness, or otherwise, of these maps.
* Conference presentation describing the design of these colour maps

Colour map naming convention

I devised the following naming convention to allow semi-automatic naming of colour maps in a way that described their key characteristics. However the resulting names are too complex, too long to type, impossible to remember, and I do not use them!

In practice I simply refer to the colour maps by a number prefixed by one or two characters to indicate whether the map is linear (l), diverging (d), rainbow (r), cyclic(c), isoluminant (i) or colour blind (cb). Thus, for example, the linear greyscale is 'l1' or 'cet-l1', the heat colour map is 'l3' or 'cet-l3' and the blue-white-red diverging map is 'd1' or 'cet-d1' etc, etc. In the visual catalogue shown further below you will see each colour map with both its simple and complex names.

Anyway, here is the description of the complex naming scheme.

• A colour map may have more than one attribute. For example, diverging-linear or cyclic-isoluminant.
• Lightness values can range from 0 to 100. For linear colour maps the two lightness values indicate the first and last lightness values in the map. For diverging colour maps the second value indicates the lightness value of the centre point of the colour map (unless it is a diverging-linear colour map). For cyclic and rainbow colour maps the two values indicate the minimum and maximum lightness values. Isoluminant colour maps have only one lightness value.
• The string of characters indicating the nominal hue sequence uses the following code

  r - red	g - green	b - blue
  c - cyan	m - magenta	y - yellow
  o - orange	v - violet
  k - black	w - white	j - grey

  ('j' rhymes with grey). Thus a 'heat' style colour map would be indicated by the string 'kryw'. If the colour map is predominantly one colour then the full name of that colour may be used. Note these codes are mainly used to indicate the hues of the colour map independent of the lightness/darkness and saturation of the colours.
• Mean chroma/saturation is an indication of vividness of the colour map. A value of 0 corresponds to a grey scale. A value of 50 or more will indicate a vivid colour map.
• Depending on whether a cyclic colour map is being used to render data that is cyclic over 360 or 180 degrees a cyclic shift of 25% may be applied.

Linear Colour Maps

CET-L1:   linear_grey_0-100_c0_n256

CET-L2:   linear_grey_10-95_c0_n256

CET-L3:   linear_kryw_0-100_c71_n256

CET-L4:   linear_kry_0-97_c73_n256

CET-L5:   linear_kgy_5-95_c69_n256

CET-L6:   linear_kbc_5-95_c73_n256

CET-L7:   linear_bmw_5-95_c86_n256

CET-L8:   linear_bmy_10-95_c71_n256

CET-L9:   linear_bgyw_20-98_c66_n256

CET-L10:   linear_gow_60-85_c27_n256

CET-L11:   linear_gow_65-90_c35_n256

CET-L12:   linear_blue_95-50_c20_n256

CET-L13:   linear_ternary-red_0-50_c52_n256

CET-L14:   linear_ternary-green_0-46_c42_n256

CET-L15:   linear_ternary-blue_0-44_c57_n256

CET-L16:   linear_kbgyw_5-98_c62_n256

CET-L17:   linear_worb_100-25_c53_n256

CET-L18:   linear_wyor_100-45_c55_n256

CET-L19:   linear_wcmr_100-45_c42_n256

Diverging Colour Maps

CET-D1:   diverging_bwr_40-95_c42_n256

CET-D1A:   diverging_bwr_20-95_c54_n256

CET-D2:   diverging_gwv_55-95_c39_n256

CET-D3:   diverging_gwr_55-95_c38_n256

CET-D4:   diverging_bkr_55-10_c35_n256

CET-D6:   diverging_bky_60-10_c30_n256

CET-D7:   diverging-linear_bjy_30-90_c45_n256

CET-D8:   diverging-linear_bjr_30-55_c53_n256

CET-D9:   diverging_bwr_55-98_c37_n256

CET-D10:   diverging_cwm_80-100_c22_n256

CET-D13:   diverging_bwg_20-95_c41_n256

CET-R3:   diverging-rainbow_bgymr_45-85_c67_n256

Rainbow Colour Maps

CET-R1:   rainbow_bgyrm_35-85_c69_n256

CET-R2:   rainbow_bgyr_35-85_c72_n256

Cyclic Colour Maps

CET-C1:   cyclic_mrybm_35-75_c68_n256

CET-C2:   cyclic_mygbm_30-95_c78_n256

CET-C3:   cyclic_rwbkr_15-85_c43_n256

CET-C4:   cyclic_wrwbw_40-90_c42_n256

CET-C5:   cyclic_grey_15-85_c0_n256

Isoluminant Colour Maps

CET-I1:   isoluminant_cgo_70_c39_n256

CET-I2:   isoluminant_cgo_80_c38_n256

CET-I3:   isoluminant_cm_70_c39_n256

CET-D11:   diverging-isoluminant_cjo_70_c25_n256

CET-D12:   diverging-isoluminant_cjm_75_c23_n256

Colour Maps for the Colour Blind

CET-CBL1:   linear-protanopic-deuteranopic_kbjyw_5-95_c25_n256

CET-CBL2:   linear-protanopic-deuteranopic_kbw_5-98_c40_n256

CET-CBD1:   diverging-protanopic-deuteranopic_bwy_60-95_c32_n256

CET-CBC1:   cyclic-protanopic-deuteranopic_bwyk_16-96_c31_n256

CET-CBC2:   cyclic-protanopic-deuteranopic_wywb_55-96_c33_n256

CET-CBTL1:   linear-tritanopic_krjcw_5-98_c46_n256

CET-CBTL2:   linear-tritanopic_krjcw_5-95_c24_n256

CET-CBTD1:   diverging-tritanopic_cwr_75-98_c20_n256

CET-CBTC1:   cyclic-tritanopic_cwrk_40-100_c20_n256

CET-CBTC2:   cyclic-tritanopic_wrwc_70-100_c20_n256