Browse Prior Art Database

Digital Color Encoding

IP.com Disclosure Number: IPCOM000043697D
Original Publication Date: 1984-Sep-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Milling, PE: AUTHOR [+2]

Abstract

In digital color displays the color hue information is coded in a composite video signal by a phase shift from the phase of the color burst signal (3.58 MHz). The phase shift of 0Πcorresponds to yellow green, and a phase shift of -90Πcorresponds to red with a slight blue tinge. For color alphanumeric and 320 x 200-pel (picture element) color graphic modes, the colors are obtained by multiplexing onto the video signal a phase-shifted version of the color burst signal. Described herein is an alternate method of obtaining the phase-shifted color signal by shifting out a pattern of 1 and 0 (black/white) video dots at the color burst frequency of 3.58 MHz. Since in the 640 x 200-pel graphic mode, the dot rate is 14.

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Digital Color Encoding

In digital color displays the color hue information is coded in a composite video signal by a phase shift from the phase of the color burst signal (3.58 MHz). The phase shift of 0OE corresponds to yellow green, and a phase shift of -90OE corresponds to red with a slight blue tinge. For color alphanumeric and 320 x 200-pel (picture element) color graphic modes, the colors are obtained by multiplexing onto the video signal a phase-shifted version of the color burst signal. Described herein is an alternate method of obtaining the phase-shifted color signal by shifting out a pattern of 1 and 0 (black/white) video dots at the color burst frequency of 3.58 MHz. Since in the 640 x 200-pel graphic mode, the dot rate is 14.3 MHz, consecutive patterns of 4 bits can be used to create consecutive color pels on a display for an effective resolution of 160 x 200 pels. A unique color is obtained from each of the 16 possible patterns of 4 bits, as shown in the figure.

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