color

https://github.com/halostatue/color

Color is a Ruby library to provide basic RGB, CMYK, HSL, and other colourspace manipulation support to applications that require it. It also provides 152 named RGB colours (184 with spelling variations) that are commonly supported in HTML, SVG, and X11 applications. A technique for generating monochromatic contrasting palettes is also included. The Color library performs purely mathematical manipulation of the colours based on colour theory without reference to colour profiles (such as sRGB or Adobe RGB). For most purposes, when working with RGB and HSL colour spaces, this won't matter. Absolute colour spaces (like CIE L*a*b* and XYZ) and cannot be reliably converted to relative colour spaces (like RGB) without colour profiles. Color 1.8 adds an alpha parameter to all <tt>#css_rgba</tt> calls, fixes a bug exposed by new constant lookup semantics in Ruby 2, and ensures that <tt>Color.equivalent?</tt> can only be called on Color instances. Barring bugs introduced in this release, this (really) is the last version of color that supports Ruby 1.8, so make sure that your gem specification is set properly (to <tt>~> 1.8</tt>) if that matters for your application. This version will no longer be supported one year after the release of color 2.0.