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.

CBS had its own “bulls eye” test pattern, and the ABC station in New York City featured the Empire State Building on its black-and-white test card in the early 1950s. Then, with color ...

He also finds the ability to stack multiple ColorBoxes and generate different signals with different test patterns, resolutions, or frame rates useful. It allows for flawless execution in the moment ...