Browse Prior Art Database

Color Normalization for Display Terminals

IP.com Disclosure Number: IPCOM000035154D
Original Publication Date: 1989-Jun-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 14K

Publishing Venue

IBM

Related People

Quarendon, P: AUTHOR [+2]

Abstract

In color graphics displays, the colors generated are not repeatable from terminal to terminal. In the technique disclosed, color correction tables are stored by each display and accessed when a particular display is attached to a host. In order to display specified colors, initial comparison with a standard set of colors is required. The correction tables depend on phosphor color and the gamma curve of each display. Correction for the former is stored at the factory and for the latter, which may vary with time, by user set-up.

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Color Normalization for Display Terminals

In color graphics displays, the colors generated are not repeatable from terminal to terminal. In the technique disclosed, color correction tables are stored by each display and accessed when a particular display is attached to a host. In order to display specified colors, initial comparison with a standard set of colors is required. The correction tables depend on phosphor color and the gamma curve of each display. Correction for the former is stored at the factory and for the latter, which may vary with time, by user set-up.

Colours generated by computer and displayed on conventional terminals are not usually accurately repeatable from terminal to terminal. As computer graphics is more widely used, it becomes more and more important to be able to produce a given color accurately and consistently. This is relevant in applications such as design and architecture.

There are two main reasons for color variation - the color of the basic phosphors and the gamma curve of the display.

This disclosure suggests alternative solutions. One is partly implemented in application software. The preferred solution is implemented entirely on the display device.

In the first embodiment, these effects are allowed for in the application software; usually by preparing appropriate video lookup tables (LUTs) and sending them to the device. This requires the software to have knowledge of the device in use. This knowledge is typically achieved by software control. Correction tables for different devices are stored on the host. When a particular device is attached, the appropriate tables are accessed.

The display device holds the correction tables and presents them to the software in response to an ENQUIRE function. The software then applies the corrections before sending LUTs to the display device.

In the second (preferred) embodiment the LUT entries passed from application program to the device would specify the color required for each stored pixel value in a device independent form. Th...