VIDEO SYNTHESIZER FOR A DIGITAL VIDEO DISPLAY SYSTEM EMPLOYING A PLURALITY OF GRAYSCALE LEVELS DISPLAYED IN DISCRETE STEPS OF LUMINANCE

摘要

ABSTRACT OF THE DISCLOSUREA digital video display system wherein the variouscharacters to be displayed are displayed in the form ofimages of the complete character rather than the standarddot-matrix pattern of the prior art. A character genera-tor in the display system stores signals representing thevarious characters to be displayed which are retrieved fromstorage in response to a character code. The signals arein the form of a binary code having a sufficient number ofbits to represent a different number of levels of gray-scale or luminance values for the various picture elementsmaking up the character image. The binary codes thusretrieved from storage are supplied to a video synthesizerthat generates the video signal to display the characterimages which may be displayed in a number of differentmodes including white-on-black, black-on-white, black-on-gray, and white-on-gray as well as different combinationsof such modes to represent a cursor. The video synthesizercan generate output voltage levels in discrete stops forthe different luminances to be employed. The voltage out-put signals differ from level to level in accordance withthe 2.2 root of luminance.