Accessible viz encodes values as redundant channels: position, pattern, label, not hue alone. Ishihara plates 1917; WCAG 2 contrast; Okabe–Ito palettes for deuteranopia.
In reports, ads and assignments it fits public dashboards, exams, print in grey, legal slides. Skip it when relying on red/green alone to mean bad/good.
Mistakes
- Failure modes 1 — relying on red/green alone to mean bad/good
- Failure modes 2 — 3-D pies and perspective bars
- Failure modes 3 — Dual axes that fake a correlation
- Failure modes 4 — Truncated axes that shout a small delta
- Failure modes 5 — Legend only, no direct labels
- Failure modes 6 — Missing source, unit or period
Fixes
- Fixes 1 — Return to public dashboards, exams, print in grey, legal slides.
- Fixes 2 — Flat, one axis, direct labels.
- Fixes 3 — Color-blind-safe palette plus pattern.
- Fixes 4 — Rewrite the title as a claim and add a source line.
Accessible viz: honour redundant channels: position, pattern, label, not hue alone, and switch when relying on red/green alone to mean bad/good.