By Donna Poulton
Before the 1960s (and color TV), most television stations turned off all programming at midnight. After 12:00 p.m., and until early in the morning, the only image you could tune into was the test pattern. The dominant and most famous test pattern was the grey scale pattern known as the “Indian Head.” It was introduced by RCA in 1939 and became “an important icon in the 1940s.” It was such a popular image that it was also used in Canada, Rhodesia, Venezuela and Sweden…and Poland (see below).
Technicians quickly glanced at the “Indian Head” to assess focus. If it was slightly blurred, they then used the lines and numbers for fine-tuning.