Chapter 7 Basic accessibility for static visualizations

7.1 Accessible Text Accompanying the Visualization

  • Accessible Font
  • Embedded tags/styles
  • Large Text
  • High Contrast

7.2 Neurodivergence

  • Limited Visual Confusion

7.3 Low Vision

7.4 Color Vision Deficiency

7.4.1 Dual encoding (never just color)

7.4.2 Color palettes

7.5 Screen Reader Users

7.5.1 Alternative Text

In R, R Markdown:

  • fig.alt in code chunk (new, just for HTML output)

  • fig.cap in code chunk as backup

  • embedded images: write alt text between square brackets

  • New: ggplot2 v3.3.4 adds alt option in labs(), with plans to propagate to Rmd, Shiny

Writing good alt text for visualizations

7.5.2 Longer Descriptions

Longer descriptions: savonliquide package

7.5.3 Converting graphics to sound, touch, text, table

  • sonify package

  • tactileR package

  • BrailleR package

    • Note: set plot title, subtitle, caption using labs()

Accessible Data Science for the Blind Using R