A test card, also known as a test pattern or start-u.p/closedown test, is a television test signal, typically broadcast at times when the transmitter is active but no program is being broadcast. Used since the earliest TV broadcasts, test cards were originally physical cards at which a television camera was pointed, and such cards are still often used for calibration, alignment, and matching of cameras and camcorders. Test cards typically contain a set of patterns to enable television cameras and receivers to be adjusted to show the picture correctly.
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