Method and apparatus for antialiasing by gamma corrected area calculation
AssigneeMicrosoft Corporation
InventorsCarroll Philip Gossett, Derek Bosch, Shouchern Alex Yen
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Abstract
A novel technique and apparatus for antialiasing in a computer graphics system is presented. The invention provides antialiasing by gamma corrected area calculation wherein the pixel coverage area is efficiently determined using cross products of the end points of line edges and the corners of the pixels. Gamma correction is advantageously achieved using linear interpolation of a Bézier curve representation of the gamma correction curve by application of the de Casteljau algorithm to programmable coefficients. The invention further provides for alpha blending of the gamma corrected area calculation for each pixel and adjustment of the area calculation for pixels with end points.
Claims22
A method of antialiasing a pixel partially covered by a line segment having first and second edges in a computer graphics system having a display comprised of a plurality of pixels having a boundary, said method comprising:
- determining a first area of pixel coverage by the line segment extending from said first edge;
- determining a second area of pixel coverage by the line segment extending from said second edge;
- determining a total area of pixel coverage from said first and second areas of pixel coverage;
- and
- determining a gamma corrected value from said total area of pixel coverage.
A system for antialiasing a pixel partially covered by a line segment having first and second edges, in a computer graphics system having a display comprised of a plurality of pixels having a boundary, said system comprising:
- first area determining logic for determining a first area of pixel coverage by the line segment extending from the first edge;
- second area determining logic for determining a second area of pixel coverage by the line segment extending from the second edge;
- total area determining logic for determining a total area of pixel coverage from the first and second areas of pixel coverage;
- and
- value determining logic for determining a gamma corrected value from said total area of pixel coverage.
Dependencies are inferred from the claim text.