Two weeks ago I wrote an article about Protanope Tools and how you can translate diagrams to make them more readable for colorblind people. This time we have closer look at the algorithms behind the two color translations.

To understand the how and why of the two color translations we first have look at the RGB color system. The acronym RGB encodes the colors Red, Green and Blue and is used on computer system color displays to—well— display colors.

Concerning red-green color blindness the first two channels (Red/Green) are sometimes not of great help. These two channels are encoding the color axis which gives a red-green colorblind person the most problems in distinguishing different shades. Therefore we are looking for a simple way to transform those two channels.

Red-Green Color Blindness Color Translation Algorithms

• Red-Green to Blue-Yellow Translation
  
  • R -> B
  • G -> G
  • G -> R

• Red-Green to Green-Magenta Translation
  
  • R -> R
  • G -> G
  • R -> B

The two translation formulas are held very simple but not less effective. They have only one major flaw: the blue channel is completely thrown out and in both cases replaced by the red channel. So you lose a third of the information in the image, all the blue information, except that if you are red-green colorblind you gain a lot of information that was previously lost in the red and green channels.

As Peter, the owner of Protanope Tools, puts it:

I say this is a strength because the simplicity makes it easy to understand exactly what’s happening, so if you know you’re going to lose all the blue information at least that won’t take you by surprise.

Thanks Peter for the information about your simple color translation algorithms you shared with us.