Colorblind Simulator

How to use it

1. Upload an image, or pick a test color and click Apply color to fill the canvas.
2. Compare the original view with the protanopia, deuteranopia and tritanopia panels.
3. Look for pairs that collapse into the same color - those are the combinations you should not rely on.
4. Clear the canvas and try another sample as needed.

Common use cases

• Checking UI palettes - verify that success and error states stay distinguishable without hue cues.
• Reviewing charts - confirm that adjacent series in a chart remain separable for colorblind readers.
• Auditing brand assets - see how a logo or banner renders under the three most common deficiency types.
• Choosing text backgrounds - make sure contrast survives, not just hue differences.

Why it stays private

Images are drawn to a local canvas and transformed pixel by pixel in your browser. Nothing is uploaded, so screenshots of unreleased products are safe to test.

FAQ

Q: How accurate is the simulation? A: It uses published RGB-to-LMS approximation matrices for the three deficiency types. It models the common red/green/blue-yellow deficiencies reasonably well, but individual vision varies, so treat it as a design aid rather than a clinical rendering.

Q: Which color space does it operate in? A: The transform is applied directly to sRGB canvas pixel values. This matches how most design-facing simulators work, though it is a simplification of full spectral modeling.

Q: Can it handle large images? A: Images are scaled into a 320 by 240 canvas before simulation, which keeps the pixel loop fast and the comparison panels aligned. Downscaling preserves color relationships well enough for palette checks.