Perceptions of matplotlib colormaps

A look at which matplotlib colormaps are most perceptual, as well as which will print well to grayscale and be accessible to viewers with color deficiencies.

Transcript

1. Perceptions of matplotlib colormaps Kristen M. Thyng Texas A&M University July 10, 2014 Kristen M. Thyng (Texas A&M) SciPy 2014 July 10, 2014 1 / 15
2. CIELAB Color Model http://eschicleypega.blogspot.com Kristen M. Thyng (Texas A&M) SciPy 2014 July 10, 2014 2 / 15
3. Lightness of matplotlib Colormaps http://matplotlib.org/examples/color/colormaps reference.html Kristen M. Thyng (Texas A&M) SciPy 2014 July 10, 2014 3 / 15
4. Lightness of matplotlib Colormaps Kristen M. Thyng (Texas A&M) SciPy 2014 July 10, 2014 3 / 15
5. Lightness of matplotlib Colormaps http://matplotlib.org/examples/color/colormaps reference.html Kristen M. Thyng (Texas A&M) SciPy 2014 July 10, 2014 4 / 15
6. Lightness of matplotlib Colormaps Kristen M. Thyng (Texas A&M) SciPy 2014 July 10, 2014 4 / 15
7. Perceived Lightness: Weber-Fechner Law (and Stevens) 1 1 2 2 3 4 4 Additional Parts Black 8 Albers, J. (1975). Interaction of color. Yale University Press. Kristen M. Thyng (Texas A&M) SciPy 2014 July 10, 2014 5 / 15
8. Improvement to Binary Colormap? Kristen M. Thyng (Texas A&M) SciPy 2014 July 10, 2014 6 / 15
9. Improvement to Binary Colormap? Kristen M. Thyng (Texas A&M) SciPy 2014 July 10, 2014 6 / 15
10. Printing to Grayscale Lots of ways to convert to grayscale Gray = (Red * 0.2126 + Green * 0.7152 + Blue * 0.0722) (or similar∗) Use luminance ∗ http://www.tannerhelland.com/3643/grayscale-image-algorithm-vb6/ Kristen M. Thyng (Texas A&M) SciPy 2014 July 10, 2014 7 / 15
11. matplotlib Colormaps in Grey Scale Kristen M. Thyng (Texas A&M) SciPy 2014 July 10, 2014 8 / 15
12. matplotlib Colormaps in Grey Scale Kristen M. Thyng (Texas A&M) SciPy 2014 July 10, 2014 8 / 15
13. matplotlib Colormaps in Grey Scale Kristen M. Thyng (Texas A&M) SciPy 2014 July 10, 2014 8 / 15
14. matplotlib Colormaps in Grey Scale Kristen M. Thyng (Texas A&M) SciPy 2014 July 10, 2014 8 / 15
15. matplotlib Colormaps in Grey Scale Kristen M. Thyng (Texas A&M) SciPy 2014 July 10, 2014 8 / 15
16. Color Blindness Protanopia (2% male population, half mild form) Deuteranopia (6% male population, mostly mild form) http://www.color-blindness.com Kristen M. Thyng (Texas A&M) SciPy 2014 July 10, 2014 9 / 15
17. Color Blindness http://aspnetresources.com/tools/colorBlindness Kristen M. Thyng (Texas A&M) SciPy 2014 July 10, 2014 10 / 15
18. Color Blindness http://aspnetresources.com/tools/colorBlindness Kristen M. Thyng (Texas A&M) SciPy 2014 July 10, 2014 11 / 15
19. Color Blindness http://aspnetresources.com/tools/colorBlindness Kristen M. Thyng (Texas A&M) SciPy 2014 July 10, 2014 12 / 15
20. Color Blindness http://aspnetresources.com/tools/colorBlindness Kristen M. Thyng (Texas A&M) SciPy 2014 July 10, 2014 13 / 15
21. Recommendations Best colormap depends on application, but for form information, perceptual colormaps are best Perceptual colormaps monotonically increase with lightness Not clear (to me) what functional relationship with L is best Many ways to convert to grayscale — luminance is a good proxy to decide on a good map Most common color blindness problem is red-green — try to avoid for reaching audiences most effectively Kristen M. Thyng (Texas A&M) SciPy 2014 July 10, 2014 14 / 15
22. Resources All around helpful information on colormaps: Matteo Niccoli: http://mycarta.wordpress.com/2012/05/29/the- rainbow-is-dead-long-live-the-rainbow-series-outline/ Comparison of 7 methods of converting to grayscale: http://www.tannerhelland.com/3643/grayscale-image-algorithm-vb6/ Color blindness: http://www.color-blindness.com Link to slides: https://github.com/dmcdougall/scipy14-colormaps Kristen M. Thyng (Texas A&M) SciPy 2014 July 10, 2014 15 / 15