Test patterns are visual images used in television broadcasting to help calibrate and adjust the quality of the picture. They typically feature geometric shapes, colors, and grayscale gradients, allowing technicians to assess aspects like color accuracy, contrast, and resolution. These patterns are essential for ensuring that viewers receive a clear and consistent image. Commonly seen during the initial setup of a TV or when a broadcast is temporarily interrupted, test patterns serve as a standard reference for both broadcast engineers and viewers alike.