A "test pattern" is a visual image used in television broadcasting to help technicians adjust and calibrate equipment. These patterns often feature geometric shapes, lines, and colors that can be analyzed for clarity and alignment. They are typically displayed when a channel is not broadcasting regular programming. Test patterns were commonly used in the early days of television, especially before the advent of 24-hour broadcasting. One famous example is the Indian Head test pattern, which featured a Native American chief's profile and was used in the United States. Today, test patterns are less common due to digital technology and automated systems.