A few years ago I worked with a client that was color blind.

Eight percent of Caucasian men are color blind, this is made of mostly Deuteranope (Green-blind), follow by Protanope (Red-blind) and very rarely Tritanopia (Blue-blind). What is even more rare is Monochromatic, total color blindness.

My client was the totally color blind. He saw in shades of greys and I can only wonder how the world looks through his eyes.

That was a huge problem to him. From little things like depending on his wife to dress to go work every morning, to more dangerous one, like not knowing if a traffic signal was red or green when he was travelling in a place where the traffic lights where horizontal instead of vertical.

And of course he sent me to talk to his wife when I arrived at his office with pantone samples.

Although I did study color theory and light physics is something that always interest me, I must confess that until then I’ve had never really though about color blindness. You could say I was a bad designer.

Joseph Albers said:

Every perception of color is an illusion…we do not see colors as they really are. In our perception they alter one another.

What is color bliness

A normal color vision person is capable of perceiving all three primary colors of light: Red, Green, and Blue.

Color blindness is the complete inability to perceive one or more of the three primary colors of light.

With color deficient vision, it is more difficult to discriminate all three dimensions of color: hue, value, and chroma. The severity of color vision deficiencies ranges from a little difficulty in distinguishing similar hues to the inability to perceive any color at all. But all people with color-deficient vision can perceive differences in value and most can see a fairly wide range of hues.

In general, if the Red value is greater than the Blue, it appears in the yellows group, and if Red is less than Blue it appears in the Blues group. A color generally appears neutral when Green equals Blue, more or less regardless of the value for Red.

Syntax highliting

Last week I’ve been involved in implementing syntax highlighting on Patternfly.

There are lots of themes and although it’s almost never an issue for color blind users, to proof this concept I decided to create one for this blog.

With that in mind and using colors picked from Googles Material Design color pallete, I came up with this theme:


<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
    <title>A Tiny Page</title>
    <link href="css/styles.css" rel="stylesheet" media="screen, print">  
  </head><!-- real comment -->
    <script language="javascript" type="text/javascript">
          function changeHeight(h) {
            var tds = document.getElementsByTagName("td");
            for(var i = 0; i < tds.length; i++) { 
              tds[i].setAttribute("height", h + "px");
    <p>Testing page</p>


import java.util.Map;
import java.util.TreeSet;

public class GetEnv {
   * let's test generics
   * @param args the command line arguments
  public static void main(String[] args) {
    // get a map of environment variables
    Map<String, String> env = System.getenv();
    // build a sorted set out of the keys and iterate
    for(String k: new TreeSet<String>(env.keySet())) {
      System.out.printf("%s = %s\n", k, env.get(k));

Side by side, the first image is the original, second is a Protanopia view, next is a Deuteranopia view and last is Monochromatic.

color theme comparison

This blog is based on jekyll and it has built in support for syntax highlighting thanks to Pygments. In case you want to use this colorblind friendly theme for Pygments, the source is here.

How to test it

There are several tools to test color blind images. After trying a few of them, I found that these two come in handy:

1. Photoshop

To test images, Adobe Photoshop under View > Proof Setup > Color Blindness, has an option to view images with Green-blind or Red-blind filters.

adobe photoshop view option as color blind

2. Chrome

On the browser, Spectrum is an excellent plugin for Chrome to test your colors.

Spectrum to test color blind on the browser

The translator

Last year, while doing the first steps with my startup Outclass, we’ve been invited to a pre acceleration program called Startup SC. We share that experience with other startups, one of them was True Vision.

They have wichcraft a way to “translate” colors for color blind people. A small device is plug into your TV or computer, the user sets up it up and it adjust hue and saturation of the image. They even developed a mobile app.

Until all devices come with this kind of solutions as default there will be a need to always test colors.