Foundations Color for Data Vis Benjamin Bach http://benjbach.me - - PowerPoint PPT Presentation

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Foundations Color for Data Vis Benjamin Bach http://benjbach.me - - PowerPoint PPT Presentation

Oct 27, 2022 302 likes •997 views

Foundations Color for Data Vis Benjamin Bach http://benjbach.me University of Edinburgh 2020 Outline What is color? Color in visualization Color Scales Sequential, diverging, categorical scales Rainbow color map Color blindness What is

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Foundations Color for Data Vis

Benjamin Bach http://benjbach.me University of Edinburgh 2020

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Outline

What is color? Color in visualization Color Scales Sequential, diverging, categorical scales Rainbow color map Color blindness

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What is Color?

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400-700nm ~120 million rods ~6 million cones

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Color Models

Subtractive Models Additive Models

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What is color?

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HSB Model: Hue, Saturation, Brightness

Color = (Brightness/Lightness, Saturation, Hue)

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HSB Color Picker

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Color in Visualization

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Visual Variables

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http://innovis.cpsc.ucalgary.ca/innovis/uploads/Publications/Publications/Carpendale_visual_variables.pdf

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Color Scales

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More examples of color scales (ColorBrewer)

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Colorbrewer.org

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Sequential Scales

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More examples of color scales (ColorBrewer)

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Sequential color scales

https://github.com/d3/d3-scale-chromatic

Single hue: Multi hue:

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Mapping color scales

Data value Linear Non-linear Stepwise

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Median Median

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Median Median

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8 18 10%

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10%

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Diverging Scales

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More examples of color scales (ColorBrewer)

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Diverging color scale

Multi hue:

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Categorical Scales

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More examples of color scales (ColorBrewer)

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I Want Hue

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Rainbow Color Maps

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More examples of color scales (ColorBrewer)

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http://innovis.cpsc.ucalgary.ca/innovis/uploads/Publications/Publications/Carpendale_visual_variables.pdf

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Rainbow: Diverging: Color Maps

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Rainbow Colormap

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Rainbow Colormap

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Color (mis)use

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Lightness perception of rainbow color maps

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Rainbow colormap

Pros:

  • Many different values
  • Compare similar values

Cons:

  • Colors hardly orderable
  • Introduces sharp jumps in values
  • Hides overall patterns
  • Overemphasizes certain values
  • Is not black/white nor colorblind save!
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Linear Rainbow map

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Color Blindness

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Protanopia Deuteranopia Tritanopia Normal vison

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"If a submitted manuscript happens to go to three male reviewers of Northern European descent, the chance that at least one will be color blind is 22 percent." 8% 0.5%

Protanopia Deuteranopia Tritanopia

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www.color-blindness.com

Normal Types of color blindness

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Colorblind safe palettes

Diverging Sequential Categorical Colorbrewer.org:

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Redundant encoding

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Further applications in DataVis

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Meaning of colors across cultures

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Take home messages:

  • Color = hue + lightness + saturation
  • Chose a color scale that fits your data
  • Avoid rainbow color palettes
  • Test your color palettes for colorblindness
  • Whatever increases accessibility for some

fraction of the population, increases accessibilty

  • verall.
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Further reading

  • Wong, Bang. "Points of view: Color blindness." (2011): 441.
  • Tamara Munzner: Visualization Analysis and Design, 2016;

Chapter 10: Map Color and Other Channels

  • https://www.color-blindness.com/types-of-color-blindness
  • Colin Ware: Information Visualization—Perception for Design,

2012