KjsCAC help you checking if the use of two colors is accessible for "normal" persons or for dichromat ones.
For 3.x version of KjsCAC, the version of KJSEmbed will be a 3.x one.
For 4.x version of KjsCAC, the version of KJSEmbed will be a 4.x one.
For other similar softwares go to the WAT-C website.
It is from this softwares that I got inspiration for KjsCAC.
The contrast and brigthness difference algorithm used is based on
the Web Content Accessibility Guidelines.
The dichromat simulation code is from an algorithm described by Hans Brettel,
Francoise Vienot and John Mollon in a paper which appeared in the "Journal
of the Optical Society of America V14", #10 pp2647.
This tool is in GPL v2 license or later version.