Color Oracle is a free colour blindness simulator for Window, Mac and Linux. It takes the guesswork out of designing for colour blindness by showing you in real time what people with common colour vision impairments will see.

Color Oracle simulates deuteranopia, protanopia and tritanopia. These are extreme forms of colour blindness – most color deficient viewers are seeing more colours. Therefore, if you design your art for people with extreme colour blindness, it will also be easily readable by those with minor colour blindness and "normal" vision.

The number of people affected by colour deficient vision is difficult to measure. Depending on the literature, one can find percentages between 1% and 12%. What is certain, however, is that colour vision deficiency almost exclusively affects males. Color Oracle uses the following numbers:

  • Deuteranopia or deuteranomoly: 5% of all males.
  • Protanopia or protanomaly: 2.5% of all males.
  • Tritanopia: Less than 0.3% of women and men.