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Color Mapping Technique

IP.com Disclosure Number: IPCOM000037759D
Original Publication Date: 1989-Jun-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Lawless, JJ: AUTHOR

Abstract

A graphics color table uses a 5 bit per color Digital-to-Analog Converter (DAC) which provides 32 levels of intensity for each color gun. To drive the highest color intensity to the video screen a "1F' hex value would be loaded and to drive no intensity for a particular color, a "00' hex value would be loaded. An 8 bit per color DAC provides 256 levels of intensity for each color gun. To drive the highest color intensity to the video screen, an "FF" hex value would be loaded, and to drive no intensity for a particular color, a "00" hex value would be loaded.

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Color Mapping Technique

A graphics color table uses a 5 bit per color Digital-to-Analog Converter (DAC) which provides 32 levels of intensity for each color gun. To drive the highest color intensity to the video screen a "1F' hex value would be loaded and to drive no intensity for a particular color, a "00' hex value would be loaded. An 8 bit per color DAC provides 256 levels of intensity for each color gun. To drive the highest color intensity to the video screen, an "FF" hex value would be loaded, and to drive no intensity for a particular color, a "00" hex value would be loaded.

The problem is how to construct 8 bits of useful information when only 5 bits are provided. A quick and accurate algorithm to solve the problem is presented. By copying the 3 high order bits of the 5 bit per color load and using them as new 2 low order bits for the 8 bit per color load (Figs. 1 and 2), a close approximation to the original color hue is achieved.

Disclosed anonymously.

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