A quick accessibility check on a design
Run a screenshot of the interface through the three approximation matrices and see whether the red-green information is still distinguishable.
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Guide
The colour vision page has a “challenge” and a “simulator”. The challenge is 16 questions, eight red-green and eight blue-yellow, with the patterns generated locally on a canvas; the simulator reads an image you upload, scales its longest side to at most 720 px, then applies the three RGB approximation matrices for colour blindness and outputs the original and the simulations as PNGs.
Updated 2026-09-272 min read
The image simulation uploads nothing: the original is drawn onto a canvas and the pixels are transformed by matrix, with the output produced as a local data: PNG.
Run a screenshot of the interface through the three approximation matrices and see whether the red-green information is still distinguishable.
Switch between the original and the simulated result on the same image to feel the difference directly.
Sixteen red-green and blue-yellow patterns with the two families scored separately, which works well for a demonstration.
No — that requires an examination by an eye specialist under standard conditions.
Uploaded images and generated patterns stay in the browser and are never uploaded; nothing but local settings is stored.
Updated 2026-09-27
Generated color-vision plates plus simulation of three types of color blindness on your images (for fun, not diagnosis)
16 plates in total: 8 red-green and 8 blue-yellow confusion colours. Every image is generated randomly and hides a two-digit number among the dots — pick the number you see.
Tips: turn your screen brightness above 70%, switch off eye-care / night mode and sit about 60cm from the screen.