The chart is composed of several features, each designed for a specific test: •
Large white circle: Allows for image geometry adjustments (image should be centered with the circles being perfectly round). •
Vertical stripe boxes: A grating with a resolution of 200
Television Lines (TVL), a measurement of image resolution on analogue TV systems, allowing adjustment of horizontal linearity and geometry. •
Horizontal stripe boxes: A grating, allowing adjustment of vertical linearity. •
Grayscale steps: Evaluating
gamma and transfer characteristics, they allow for contrast and brightness adjustments (at least 6 to 8 steps should be visible) •
Concentric circles: Allow to test cathode-ray beam sharpness and focus •
Resolution wedges: The gradually expanding lines near the center, labeled with periodic indications of the corresponding
spatial frequency, allow checking of image resolution. •
Border arrows: Allow for
overscan adjustments. •
Numbers: Going from 200 to 800, they correspond to TV Lines (TVL). Used with early monochrome TV systems, this chart was useful in measuring image resolution, determined by inspection of the image as displayed on a CRT. On such systems an important measure is the limiting horizontal resolution, affected by hardware and transmission quality (vertical resolution is fixed and determined by the video standard used, usually
525 lines or
625 lines). ==Usage==