Manipulate Colors With jQuery: xcolor
xcolor is a jQuery plugin which allows you to perform many different manipulations on colors.
First of all, it can parse and convert colors between different formats with methods like getRGB(), getHSV() or getHEX().
Another powerful feature is extracting or combining colors (like red + blue would result in purple).
Also, it can generate complementary colors, lighten/darken them, find analogous/monochromatic colors of an item and much more.
The plugin comes with other functions where the most interesting one is: isReadable which performs a readability test for a text on a given background.
Tip: To perform the same actions on the server-side, the author also has a PHP class with very similar features.
Compatibility: All Major Browsers