What looks like random blocks of color to the untrained eye is actually a carefully laid-out test pattern. For example, the colors yellow, cyan, green, magenta, red, blue actually goes from ...

Learn how to tweak your desktop or laptop display using free test patterns or the built-in utility in Windows or Mac OS X.

The test patterns can be downloaded from the AVFoundation page on Apple's website under Related Resources > Color Test Patterns, with complete instructions available in Apple's support document.