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Gamma-Correcting Digital-To-Analog Converter

IP.com Disclosure Number: IPCOM000064751D
Original Publication Date: 1985-Sep-01
Included in the Prior Art Database: 2005-Feb-19

Publishing Venue

IBM

Related People

Authors:
Miessler, MH [+details]

Abstract

In a digital-to-analog converter (DAC) for generating an eight grey level video for a CRT display, three current switches, selected by three digital input signals, provide a DAC with eight linear steps. An additional current switch operated when any one of the inputs is active generates an additional output current added to the linear DAC output. This gives an approximator to gamma correction by providing an increased initial step. In high-speed digital-to-analog conversion of video signals the problem is to achieve fast response and at the same time have an adjustable, non-linear, transfer function to compensate for the effect of the CRT gamma. This disclosure offers a solution by approximating a non-linear transfer curve by a step combined with a linear section.