Color systems encodes values as hue, value and chroma mapped to category or magnitude. Munsell 1905; Brewer palettes (1994–) for maps; OKLCH in modern CSS.
In reports, ads and assignments it fits legends, brand systems, accessible data color. Skip it when rainbow defaults, or encoding two quantities in one hue.
Mistakes
- Failure modes 1 — rainbow defaults, or encoding two quantities in one hue
- 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 legends, brand systems, accessible data color.
- 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.
Color systems: honour hue, value and chroma mapped to category or magnitude, and switch when rainbow defaults, or encoding two quantities in one hue.