The patterns were really calibration tools for engineers, helping the TV technicians adjust the quality of the transmission and you at home could adjust your rabbit ears.

You might have seen images of old TVs with a series of colorful bars, called a test pattern. What were these for, and are ...

In short, the black bars appear because the video's aspect ratio doesn't match your TV's. While companies like LG have released 21:9 TVs in the past, they have never really caught on.