Method for generating a subpixel mask for computer graphics system and apparatus thereof
First Claim
Patent Images
1. A method for generating an n×
- n subpixel mask of a pixel for antialiasing by receiving Δ
X and Δ
Y values of an edge having a slope and an initial value of a cross distance, the method comprising the steps of;
forming subblocks by dividing the pixel into n subblocks depending on the slope;
calculating a subblock coverage by;
determining a pair of reference points depending on the slope of the edge,calculating cross distances (de) defined by the distance from one of the reference points to an intersection point of the edge and a pixel boundary,subtracting a slope ratio value from a first cross distance after calculating a corresponding cross distance from the initial value of the first cross distance by an interpolation method and calculating slope ratio values of the formed subblocks, including calculating a slope ratio value (mk), by drawing a first line parallel to another pixel boundary line at the intersection point and then obtaining a distance from the first line to the edge, in the subblock units, and calculating the subblock coverage (hk) as hk =de-mk ; and
generating an n×
n subpixel mask depending on the calculated subblock coverage, whereby aliasing generated at the edge is removed.
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Abstract
In a computer graphics system, a method for generating a subpixel mask for polygon edges directly by an operation without using a look-up table, includes the steps of forming subblocks by dividing a pixel into n subpixels depending on the slope of the polygon edge, calculating subblock coverage which is a distance from the pixel boundary to the intersection point of n subblocks and polygon edge, and generating an n×n subpixel mask depending on the calculated subblock coverage. In an apparatus using the method, edge-generated aliasing is removed.
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Citations
16 Claims
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1. A method for generating an n×
- n subpixel mask of a pixel for antialiasing by receiving Δ
X and Δ
Y values of an edge having a slope and an initial value of a cross distance, the method comprising the steps of;forming subblocks by dividing the pixel into n subblocks depending on the slope; calculating a subblock coverage by; determining a pair of reference points depending on the slope of the edge, calculating cross distances (de) defined by the distance from one of the reference points to an intersection point of the edge and a pixel boundary, subtracting a slope ratio value from a first cross distance after calculating a corresponding cross distance from the initial value of the first cross distance by an interpolation method and calculating slope ratio values of the formed subblocks, including calculating a slope ratio value (mk), by drawing a first line parallel to another pixel boundary line at the intersection point and then obtaining a distance from the first line to the edge, in the subblock units, and calculating the subblock coverage (hk) as hk =de-mk ; and generating an n×
n subpixel mask depending on the calculated subblock coverage, whereby aliasing generated at the edge is removed. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
- n subpixel mask of a pixel for antialiasing by receiving Δ
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10. An apparatus for generating an n×
- n subpixel mask of a pixel for antialiasing in a computer graphics system by receiving Δ
X and Δ
Y values of an edge having a slope and an initial value of a cross distance, the apparatus comprising;a slope ratio value calculator for calculating a slope ratio value by selecting the Δ
X or the Δ
Y value depending on the slope;a cross distance interpolator for calculating the cross distance necessary for computing subblock coverage using an interpolation method, receiving the initial value of the cross distance, and selecting the initial value for use in computing the subblock coverage; a subblock coverage calculator for calculating the subblock coverage, receiving the slope ratio value output from said slope ratio value calculator and the cross distance output from said cross distance interpolator, wherein said subblock coverage calculator includes a plurality of subtractors for subtracting an output of said subblock coverage calculator from an output of said cross distance interpolator; data converting means receiving the subblock coverage output from said subblock coverage calculator for converting the subblock coverage into data for setting a subpixel mask; and a subpixel mask generator, receiving the data from said data converting means, for generating an n×
n subpixel mask depending on the slope and the cross distance output from said cross distance interpolator, whereby aliasing generated at the edge is removed. - View Dependent Claims (11, 12, 13, 14)
- n subpixel mask of a pixel for antialiasing in a computer graphics system by receiving Δ
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15. An apparatus for generating a subpixel mask of a computer graphics system wherein aliasing generated at triangle edges is removed, said apparatus comprising:
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a first edge processor for generating an n×
n subpixel mask for a pixel passing over a first edge by receiving the Δ
X1 and Δ
Y1 values of the first edge and an initial value of a cross distance;a second edge processor for generating an n×
n subpixel mask for a pixel passing over a second edge by receiving Δ
X2 and Δ
Y2 values of the second edge and the initial value of the cross distance;a third edge processor for generating an n×
n subpixel mask for a pixel passing over a third edge by receiving Δ
X3 and Δ
Y3 values of the third edge and the initial value of the cross distance; andan AND gate for performing an AND operation, receiving the outputs of said first, second, and third edge processors.
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16. A method for generating an n×
- n subpixel mask of a pixel for antialiasing by receiving Δ
X and Δ
Y values of an edge having a slope and an initial value of a cross distance, the method comprising;forming subblocks by dividing the pixel into n subblocks depending on the slope; calculating subblock coverage by subtracting a slope ratio value from a first cross distance after calculating a corresponding cross distance from the initial value of the first cross distance by an interpolation method and calculating slope ratio values of the formed subblocks; generating an n×
n subpixel mask depending on the calculated subblock coverage, whereby aliasing generated at the edge is removed;obtaining an error correction value by adding and sorting the subblock coverage; converting the subblock coverage and error correction value into data for setting a subpixel mask; and setting a subpixel mask depending on the magnitude of the slope, the data, and sign of the first cross distance.
- n subpixel mask of a pixel for antialiasing by receiving Δ
Specification