Colour Blindness Simulator
Simulate colour blindness and low vision on an image or a screenshot, then test the WCAG contrast of every colour pair in your palette.
Everything is created in your browser: no image or colour is sent to a server.
About this tool
This simulator shows how an image, a screenshot or a palette looks with different colour vision: protanopia, deuteranopia and tritanopia, their milder forms (protanomaly, deuteranomaly, tritanomaly) with a severity slider, achromatopsia and blurred low vision. The maths uses the matrices published by Machado, Oliveira and Fernandes (2009), applied in linear RGB. Compare the original and the simulation side by side, with a before and after slider or in a grid of every vision type.
For a palette, the tool builds the WCAG 2 contrast matrix of every colour pair: AA and AAA levels for normal and large text, plus the 3:1 threshold for graphical objects, with a text preview on each background. The matrix can be recalculated for each vision type and flags colours that become hard to tell apart. Export the simulations as PNG and the matrix as CSV. Your images stay in your browser.
- Protanopia, deuteranopia and tritanopia
- Milder forms with a severity slider
- Achromatopsia and low vision (blur)
- Side by side, before and after slider and grid
- WCAG AA and AAA contrast matrix for the palette
- PNG export of simulations and CSV of the matrix
How to use it
- Drop an image, paste a screenshot or switch to the Palette tab.
- Choose a vision type and, for the milder forms, the severity.
- Compare with the before and after slider or the grid of every vision.
- Export the simulation as PNG or the contrast matrix as CSV.