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Shading by Texture Variation

IP.com Disclosure Number: IPCOM000034456D
Original Publication Date: 1989-Feb-01
Included in the Prior Art Database: 2005-Jan-27
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Todd, SJP: AUTHOR [+2]

Abstract

This article describes a method that allows the number of different colors required to display a textured surface of an image-synthesized object to be reduced, thus facilitating output by low resolution visual devices. Background Solid texturing [*] is a convenient method to produce a random pattern effect on the surface of complicated shapes. In the simplest embodiment, a three-dimensional 'pseudo-fractal' scalar field is defined over the space occupied by the object, but is evaluated only at its surface. Ranges in value of the field are made to correspond to different colors that a lighting model program is subsequently applied to. This approach produces a large range of different colors from the interaction of texture and lighting which can be a problem for low color-resolution displays or limited-color printing processes.

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Shading by Texture Variation

This article describes a method that allows the number of different colors required to display a textured surface of an image-synthesized object to be reduced, thus facilitating output by low resolution visual devices. Background Solid texturing [*] is a convenient method to produce a random pattern effect on the surface of complicated shapes. In the simplest embodiment, a three- dimensional 'pseudo-fractal' scalar field is defined over the space occupied by the object, but is evaluated only at its surface. Ranges in value of the field are made to correspond to different colors that a lighting model program is subsequently applied to. This approach produces a large range of different colors from the interaction of texture and lighting which can be a problem for low color- resolution displays or limited-color printing processes. Solution A way to overcome this difficulty is to apply the lighting model calculations first . The resulting intensities are later used as the key to select texture values. Texture colors must now be chosen to give a spectrum between dark and light tones. The illusion of shading is thus recreated by subtle changes in the texture pattern itself. In effect, the texture is being used to produce a camouflaged halftoning. Thus shading that was produced by many color mixtures is now produced from a limited selection of stored texture patterns. One effect of the new process is that edges appear emphasized, because the...