Test the palette with a color-vision simulator
For charts that rely on color differences, use color-vision simulation on the chosen palette to improve accessibility and mitigate undetected color collisions for readers with color-vision deficiency.
- purpose:refine
- basis:heuristic
- quality:accessibility
- lever:encoding
- needs:color-vision-deficiency
- polish:palette
advice
Simulate color-vision deficiencies
Test the palette with a color-vision simulator before publishing. For example, preview the same colors under different types of colorblindness and revise color pairs that collapse together.
reason
Why simulation is necessary
A palette can look distinct to the designer and still fail for readers with color-vision deficiencies. Simulation exposes those collisions before the chart is published.
Mechanism: Viewing the palette through color-vision simulations shows whether readers who perceive color differently can still distinguish the encoded differences.
Evidence: The post recommends checking whether chosen colors can be distinguished by colorblind people and lists simulators that show how colors appear for different types of colorblindness (https://www.datawrapper.de/blog/colorguide">Muth, 2018).
context
Use when color differences carry meaning
- User Goal: Keep color-coded distinctions readable for more readers.
- Task: Validate whether series, categories, or value steps remain separable.
- Data: Any data encoded with multiple meaningful colors.
- Chart Setting: The chart depends on color differences to communicate distinctions.
- Audience: Readers may include people with different types of color-vision deficiency.
- Success Criterion: The encoded colors remain distinguishable in simulation.
exceptions
Do not use when color is not carrying the distinction
Break it when: The chart does not rely on color differences for interpretation. Why: There are no meaningful color distinctions to validate.
costs
Tradeoffs of simulation review
Sacrifice: You add a review step to the palette workflow.
Risk: A palette that looks fine in normal vision may merge in simulated views.
Mitigation: Run the simulation while choosing colors, not only at the end.
mistakes
Common misuse of accessible palettes
Mistake: Judging the palette only in normal vision. Why it fails: It hides color collisions that some readers will experience.
check
Check whether colors collapse in simulation
Failure Sign: Two or more encoded colors become hard to tell apart in the simulation.
Quick Check: Run the palette through one color-vision simulator.
Stronger Test: Check the palette under multiple simulated types of colorblindness.
fix
Fix color collisions
- Replace colors that merge under simulation.
- Increase separation between colors that become similar.
- Re-run the simulator after each palette revision.