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 Title: |
US6329977:
Pre-filtered antialiased lines using distance functions
[ Derwent Title ]
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| Country: |
US United States of America
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| Inventor: |
McNamara, Robert S.; Portola Valley, CA
McCormack, Joel J.; Boulder, CO
Jouppi, Norman P.; Palo Alto, CA
Claffey, James T.; Groton, MA
Knittel, James M.; Groton, MA
Seiler, Larry D.; Boylston, MA
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| Assignee: |
Compaq Computer Corporation, Houston, TX
other patents from COMPAQ COMPUTER CORPORATION, INC. (755619) (approx. 2,058)
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| Published / Filed: |
2001-12-11
/ 1998-03-10
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| Application Number: |
US1998000037412
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| IPC Code: |
Advanced:
G06T 11/20;
G09G 5/20;
Core:
more...
IPC-7:
G06T 11/20;
G06T 11/40;
G09G 5/10;
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| ECLA Code: |
G06T11/20L; G09G5/20;
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| U.S. Class: |
Current:
345/589;
345/443;
345/611;
Original:
345/147;
345/443;
345/432;
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| Field of Search: |
345/441,443,147,505,509,419,436,425,514
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| Priority Number: |
| 1998-03-10 |
US1998000037412 |
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| Abstract: |
A computer graphics system renders an image on a display device using improved pre-filtering techniques that minimize aliasing artifacts in the image, particularly at the endpoints of lines. To anti-alias the image, a plurality of edges are placed near a line in the image. An edge function represents the edge. This edge function is multiplied by a scale factor to produce a distance function. This scale factor is the reciprocal of the Euclidean length of the line. The distance function is evaluated to determine the distance of selected pixels from each edge in units of pixels. These distances determine the intensity value for each selected pixel. Pixels on or beyond an edge, with respect to the line, are given a minimum intensity value; pixels inside all edges are given intensity values corresponding to their distances from the edge. An intensity function describing a relationship between pixel distances from the edges and their corresponding intensity values is developed. The intensity function can be implemented in a look-up table or approximated with hardware.
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| Attorney, Agent or Firm: |
Sherry, LeahOppenheimer, Wolff & Donnelly ;
McRoss, Loren H. ;
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| Primary / Asst. Examiners: |
Luu, Matthew; Harrison, Chante'
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| Maintenance Status: |
CC Certificate of Correction issued
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| INPADOC Legal Status: |
Show legal status actions
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| Family: |
None
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First Claim:
Show all 40 claims |
We claim:
1. A computerized method for rendering an image defined by pixels, comprising the steps of:
- placing a mask a predetermined distance outside of a line of the image, the mask including a plurality of edges which bound the line, each of the plurality of edges being defined by distance evaluators;
- selecting a pixel within the mask;
- determining a distance value representing a distance of the selected pixel from a corresponding edge of the mask; and
- determining an intensity value for the selected pixel based upon the distance value, the determined intensity value improving the perceived quality of the images by reducing aliasing artifacts when the selected pixel is intensified according to the determined intensity value.
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| Background / Summary: |
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| Drawing Descriptions: |
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| Description: |
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| Forward References: |
Show 17 U.S. patent(s) that reference this one
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| Foreign References: |
None
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| Other References: |
Feibush et al., "Synthetic Texturing Using Digital Filters", Cornell University, 1980.*
Pineda, Juan, "A Parallel Algorithm for Polygon Rasterization," Apollo Computer Inc., 1988, ACM #0-89791-275-6/88/008/0017.
Gupta et al., "Filtering Edges for Gray-Scale Displays," Carnegie-Mellon University, 1981, ACM #0-8971-045-1/81-0800-0001.
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