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Smooth Pel Scrolling in a Display System

IP.com Disclosure Number: IPCOM000037342D
Original Publication Date: 1989-Dec-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

DiNicola, P: AUTHOR [+3]

Abstract

In some types of all-points-addressable graphics display systems, where bit plane or lateral bit encoding techniques are used, currently available pel scrolling techniques which perform pel scrolling prior to determination of color information for a pel have the disadvantage that color information may be distorted since the color information is dependent upon the lateral position of digital information represented in the bit plane or linear encoding of logical pels.

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Smooth Pel Scrolling in a Display System

In some types of all-points-addressable graphics display systems, where bit plane or lateral bit encoding techniques are used, currently available pel scrolling techniques which perform pel scrolling prior to determination of color information for a pel have the disadvantage that color information may be distorted since the color information is dependent upon the lateral position of digital information represented in the bit plane or linear encoding of logical pels.

Scrolling is required when a screen viewport is smaller in size than an all- points-addressable graphics buffer. Scrolling side to side (commonly called panning) requires movement of the image on a stream on a dot-to-dot basis. This allows the viewport window boundary to be defined at any position on the screen.

The circuit shown in the figure provides a means for providing pel scrolling wherein scrolling information is added to the data screen at a point after bit plane image or lateral bit encoded hierarchy image has been determined and color added. Pel information stored in bit plane 12 is transferred to select color register 14 where color information is determined and added.

The output from select color register 14, which now represents a selected color, such as for example, green, is transmitted to serial- to-parallel converter 16 which provides deserialization of the pel data stream containing the single color information. For example, the serial-to-para...