A popular test card in the US, which you can still see in some digitizations of black-and-white era recordings, is RCA's "Indian Head" card, named after the lin

A popular test card in the US, which you can still see in some digitizations of black-and-white era recordings, is RCA's "Indian Head" card, named after the line drawing at the top for subjective sharpness checking: https://upload.wikimedia.org/wikipedia/commons/1/1b/RCA_Indian_Head_test_pattern.JPG https://upload.wikimedia.org/wikipedia/commons/1/1b/RCA_Indi... I'm rather fond of that test pattern because it was usually generated by a dedicated piece of hardware that scanned a CRT beam across a metal plate with the image on it. This was to produce a more reliable source image than the more common practice of pointing a camera at a test card in the studio - and is an odd predecessor to today's test-pattern generators.