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Aspect Ratio Correction for PC Graphics On Large High Resolution Displays

IP.com Disclosure Number: IPCOM000037397D
Original Publication Date: 1989-Jan-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Blackard, JW: AUTHOR [+2]

Abstract

By modifying the bit map of a PC color graphics image, it is possible to map the color graphics image to a display of higher resolution and maintain the proportionate shapes of geometric objects in the image.

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Aspect Ratio Correction for PC Graphics On Large High Resolution Displays

By modifying the bit map of a PC color graphics image, it is possible to map the color graphics image to a display of higher resolution and maintain the proportionate shapes of geometric objects in the image.

A PC color graphics image is 640 x 200 pels (picture elements) with a pel aspect ratio of approximately 2.1:1. The high resolution display which was used for the emulation is an all-points-addressable (APA) display with a square pel ratio and a pel image greater than or equal to 1280 x 1024 pels. The problem is to modify the color graphics image and map it to the high resolution display with an aspect ratio of 1:1 so that geometric objects, such as circles, produced on the lower resolution display will maintain their proportionate shape when transferred to the high resolution screen.

The problem is solved by changing the aspect ratio of the image to the square 1:1 ratio characteristic of the high resolution display. Since the color graphics image was produced for a display with a 2.1:1 aspect ratio, the correction is made by mapping every 2 pels to a 4x4 pel box. Each PC display pel maps to a 2x4 pel box on the high resolution display. The new image is a 1280 x 800 pel resolution image which is then centered onto the high resolution display. The simplicity of the approach enables the programmer to easily code his design. In addition, this algorithm produces an image on the large high r...