Free tool
Your page, seen differently
About one man in twelve, and one woman in two hundred, perceive colours differently, eyes blur with age, and everyone has squinted at a phone in the sun. Pick a filter and compare with the normal view.
What to look for
01
Colour alone
Links only recognisable by their colour, red “error” and green “success”, a chart legend in red and green: in deuteranopia, all of it becomes the same khaki.
Add an underline, an icon, a word.
02
Contrast
Under the cataract and sun filters, pale grey text and white text on photos are the first to go.
Check your colours with our contrast tool.
03
Size and structure
Under the blur, can you still find the headings, the buttons, the phone number? Large, well-spaced elements survive.
Text of at least 16 px is a good start.
How the filters work
Colour blindness filters apply the matrices published by Machado, Oliveira and Fernandes (2009), which recompute each colour as the cones concerned would perceive it. Achromatopsia shows luminance only. Low vision is a blur; cataracts, a blur with a yellow veil and less contrast; the sun, a strong washing out of the screen. Everything happens in your browser, on a copy of the page without its scripts.
