1 A method of presenting graphical or pictorial images in which the beam of a cathode-ray tube (CRT) is turned on as it moves from one position to another, thus creating a line. (The pen of a pen plotter may sometimes be operated in this way.) In a CRT the complete picture is created from a sequence of lines, which need to be regularly refreshed to ensure a flicker-free picture. The amount of information that can be displayed depends on the number of lines that can be drawn before the image needs to be refreshed. Compare raster-scan display.