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Colorblindness Simulation with JavaScript.


Around 4% of humans have some form of colorblindness. Since that's a significant portion of your web site traffic, it's probably worth doing some testing for how your site would look to those users. One way is the simulate.js from For each image in an array of images, this JavaScript adds a new canvas element with shifted colors. Below is an example usage for Deuteranope type vision. The script also includes functions for Protanope and Tritanope type vision.

var images = scope.getElementsByTagName("img");
for (var i = 0; i < images.length; i++) {
  Color.Vision.Simulate(images[i], {
    type: "Deuteranope",
    callback: function(canvas) {

Below is the script in action: the fruit bowl and rainbow images are shown normally, and below each is simulated with deuteranopia, protanopia finally tritanopia.

Alessi fruit bowl, filled by Dirk Ingo Franke / CC 1.0 Public Domain Rainbow from Budapest by Takkk / CC 3.0

The canvas element seems a tad unreliable - refresh the page once or twice to get the new images to load. It also can't be added when Codepen.


Tags: accessibility code javascript

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