Method and apparatus for anti-aliasing scan conversion
Methods and apparatuses for anti-aliasing scan conversion. In one aspect of the invention, an exemplary method to scan convert an image on a data processing system includes: sampling the image in a first direction to generate first signals for points along a second line in a second direction using a closed form solution for a convolution integral with a first kernel; and weighting the first signals for the points according to a second kernel in the second direction to generate a second signal for a pixel. In one example according to this aspect, the closed form solution is tabulated in a look up table. After entries are looked up from the look up table according to the image along a first line in the first direction on a first point of the points, the entries are combined to generate one of the first signals for the first point.
1. A method to scan convert an image on a data processing system, the method comprising:
evaluating a closed form solution for a convolution integral using a first kernel convolved with the image in a first direction to generate first signals;
after generating the first signals using the closed form solution, supersampling the first signals to produce points along lines in a second direction using vectorized operations, the second direction being the same direction for storing pixels of a displayed image in a vectorized circuit; and
computing weighted sums of the points according to a second kernel in the second direction to generate the pixels of the displayed image in the second direction.
2. A method as in claim 1 wherein the closed form solution is tabulated in a look up table.
3. A method as in claim 2 wherein said evaluating comprises:
looking up entries from the look up table according to the image along a first line in the first direction, the first line being on a first point of the points; and
combining the entries to generate one of the first signals for the first point.
4. A method as in claim 1 wherein the closed form solution is a solution to an integral of the first kernel.
5. A method as in claim 1 wherein the closed form solution is a solution to a convolution integral of a signal with the first kernel.
6. A method as in claim 5 wherein the first kernel is a piecewise function.
7. A method as in claim 1 wherein the first signals include no contribution from a kernel that is a function of a position along the second direction.
8. The method of claim 1 , wherein the first direction is a vertical direction of a display and the second direction is a horizontal direction of the display.
9. A machine readable medium containing executable computer program instructions which when executed by a data processing system cause said system to perform a method to scan convert an image on the data processing system, the method comprising:
evaluating a closed form solution for a convolution integral using a first kernel convolved with the image in a first direction to generate first signals;
after generating the first signals using the closed form solution, supersampling the first signals to produce points along lines in a second direction using vectorized operations, the second direction being the same direction for storing pixels of a displayed image in a vectorized circuit; and
computing weighted sums of the points according to a second kernel in the second direction to generate the pixels of the displayed image in the second direction.
10. A medium as in claim 9 wherein the closed form solution is tabulated in a look up table.
11. A medium as in claim 10 wherein said evaluating comprises:
looking up entries from the look up table according to the image along a first line in the first direction, the first line being on a first point of the points; and
combining the entries to generate one of the first signals for the first point.
12. A medium as in claim 9 wherein the closed form solution is a solution to an integral of the first kernel.
13. A medium as in claim 9 wherein the closed form solution is a solution to a convolution integral of a signal with the first kernel.
14. A medium as in claim 13 wherein the first kernel is a piecewise function.
15. A medium as in claim 9 wherein the first signals include no contribution from a kernel that is a function of a position along the second direction.
16. A data processing system to scan convert an image, the data processing system comprising:
data storage;
a processor coupled to the data storage, wherein the processor is operative to evaluate a closed form solution for a convolution integral using a first kernel convolved with the image in a first direction to generate first signals,
wherein the processor is operative to supersample the first signals to produce points along lines in a second direction using vectorized operations after the first signals are generated, the second direction being the same direction for storing pixels of a displayed image in a vectorized circuit,
and wherein the processor is further operative to compute weighted sums of the points according to a second kernel in the second direction to generate pixels of the displayed image in the second direction.
17. A data processing system as in claim 16 wherein the closed form solution is tabulated in a look up table.
18. A data processing system as in claim 17 wherein
the processor is operative to look up entries from the look up table according to the image along a first line in the first direction, the first line being on a first point of the points,
and the processor is operative to further combine the entries to generate one of the first signals for the first point.
19. A data processing system as in claim 16 wherein the closed form solution is a solution to an integral of the first kernel.
20. A data processing system as in claim 16 wherein the closed form solution is a solution to a convolution integral of a signal with the first kernel.
21. A data processing system as in claim 20 wherein the first kernel is a piecewise function.