Green–red simulation
Green–Red Color Blindness Simulator: Find the Collision, Then Fix the Cue
Quick answer
A simulator shows where red and green stop carrying distinct information.
Upload the real design, compare both protan and deutan views, and look for labels, states, lines, or regions that merge. If meaning disappears, keep the colors if you like—but add a second cue such as text, shape, pattern, position, or line style.
Run the image simulatorThe five-minute audit
- Use a representative image. Include the real chart legend, error message, selected state, map route, or status control—not a palette swatch alone.
- Check protan and deutan separately. “Red-green” covers different deficiencies. A design can fail in one view more clearly than the other.
- Find the lost job. Ask what the color was supposed to communicate: category, urgency, direction, selection, or change.
- Add one non-color cue. Label it, change its shape, add a pattern, move it, or give it a distinct line style.
- Simulate again. The repaired version should preserve the same meaning even when its colors converge.
Common collisions and the fastest repair
Red error / green success
Add an icon and a plain-language status: “Error” or “Saved.” Do not make the user infer the state from color.
Red series / green series
Label lines directly and use a solid line for one series and a dashed line for the other.
Red route / green route
Use different stroke patterns or symbols at regular intervals, then repeat the distinction in the legend.
Green selected / red blocked
Pair selection with a check mark and blocked state with a lock or stop icon plus text.
Read the output without relying on the simulated colors
Our simulator produces Original, Simulated, and Difference views. The Difference view converts pixel change into brightness, so you can locate altered regions without depending on the same red and green signals under review.
Read each Difference map on its own. It is auto-scaled for that result, so its brightness is useful for locating change inside one image—not for ranking absolute change between two cards.
What the simulator cannot tell you
A simulation is a model-based preview, not a diagnosis and not an accessibility pass or fail. People with the same named deficiency can perceive colors differently, and displays and lighting change the result.
Use a separate contrast checker for text and interface contrast. When the decision affects safety, education, work, or another high-impact setting, include people with color vision deficiencies in the review.
Original field note
Use “meaning survived” as the stopping rule.
Do not keep adjusting colors until every simulated image looks dramatically different. Stop when a person can identify the same category, state, route, or trend without needing the color name. That makes the audit about the information the design carries, not about chasing a particular shade.