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Overall Gamma Correction for Halftone Displays

IP.com Disclosure Number: IPCOM000062357D
Original Publication Date: 1986-Nov-01
Included in the Prior Art Database: 2005-Mar-09

Publishing Venue

IBM

Related People

Authors:
Chase, BD [+details]

Abstract

In a graphics display for halftone images, the grey levels are arranged so that the eye perceives them as being equally distributed in steps from black to white. For a display gamma of n the digital data to be displayed is preprocessed using a power law with the reciprocal of the display gamma as the exponent to provide visually corrected display intensity with an overall gamma of one to match that of the eye. In the case of a display with no grey level capability the pels used are simply on or off and the overall effect tends to be somewhat granular, although this depends on the pel density. In the case where the display has a small number of grey levels available, say, between 4 and 16, then halftoning can still be used such that by varying the dot density all intermediate grey levels can be represented.