Colour-blind safe palette and a no-colour-alone rule #56

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opened 2026-08-31 17:30:07 +02:00 by robert · 0 comments

robert commented

2026-08-31 17:30:07 +02:00

(Migrated from git.butzei.de)

Goal

The Time 2 has 64 colours after years of black and white, which makes it easy to start encoding meaning in colour alone. Roughly 8% of men have a colour vision deficiency, and this is far cheaper as a rule from day one than as a retrofit across three views.

Acceptance criteria

Palette chosen and documented in docs/DESIGN.md, checked against deuteranopia, protanopia and tritanopia simulation
No state is signalled by colour alone - every colour cue paired with shape, position or text
Red/green never used as the sole distinction between two states
Verified specifically for: GPS quality, speed source, off-route state, HR zones, sensor alerts
Contrast checked on e-paper in direct sunlight, not only on the emulator
Palette defined as named constants in one header, not scattered literals

Files

watchapp/src/c/palette.h
docs/DESIGN.md

Notes

HR zones are the obvious trap: they are conventionally five colours and nothing else.

## Goal The Time 2 has 64 colours after years of black and white, which makes it easy to start encoding meaning in colour alone. Roughly 8% of men have a colour vision deficiency, and this is far cheaper as a rule from day one than as a retrofit across three views. ## Acceptance criteria - [ ] Palette chosen and documented in `docs/DESIGN.md`, checked against deuteranopia, protanopia and tritanopia simulation - [ ] **No state is signalled by colour alone** - every colour cue paired with shape, position or text - [ ] Red/green never used as the sole distinction between two states - [ ] Verified specifically for: GPS quality, speed source, off-route state, HR zones, sensor alerts - [ ] Contrast checked on e-paper in direct sunlight, not only on the emulator - [ ] Palette defined as named constants in one header, not scattered literals ## Files - `watchapp/src/c/palette.h` - `docs/DESIGN.md` ## Notes HR zones are the obvious trap: they are conventionally five colours and nothing else.