Video Test Patterns
Video test patterns are used as a technical reference, in order to analyse and maintain the qualities of a video signal.
The most common patterns are color bars, such as the ones shown in this illustration.
A lot of information can be gleaned from viewing test patterns on a well-calibrated video monitor, but to analyse the signal in detail, a waveform monitor and/or vectorscope should be used.
There are two ways to view the technical characteristics of a video signal: As a waveform representation (left) and as a vector representation (right). To save space these two views can be overlaid (as in the first example next to the color bars).
See more examples of test patterns with waveform/vectorscope displays.