Anti-aliasing of a graphical object

• US 20090058880A1
• Filed: 09/04/2007
• Published: 03/05/2009
• Est. Priority Date: 09/04/2007
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Tremblay, Christopher
• Granted Patent: US 8,294,730 B2
• Time in Patent Office: Days
• US Class Current: 345/611
• CPC Class Codes: G06T 11/203 Drawing of straight lines or curves
• CPC Class Codes: G06T 15/503 Blending, e.g. for anti-aliasing
• CPC Class Codes: G06T 2200/12 involving antialiasing
• CPC Class Codes: G06T 2207/20192 Edge enhancement; Edge preservation
• CPC Class Codes: G06T 5/002 Denoising; Smoothing noise processing or correction adapted to be used in an image pickup device containing and electronic image sensor H04N23/81, H04N25/60 - H04N25/67
• CPC Class Codes: G06T 5/70 Denoising; Smoothing
• CPC Class Codes: G09G 2320/02 Improving the quality of display appearance
• CPC Class Codes: G09G 5/00 Control arrangements or circuits for visual indicators common to cathode-ray tube indicators and other visual indicators image data processing or generation, in general G06T

Abstract

A method for rendering graphical data is provided. In one embodiment, the method includes rendering an aliased version of one or more polygons and sampling one or more edges of the aliased polygons. The method also includes calculating a curve that approximates the edge portion and intersects a set of pixels, determining the proportional areas of the pixels located between the curve and the aliased edge portion, and rendering an anti-aliased version of the edge portion based on the proportional areas. Various devices, machine-readable media, and other methods for anti-aliasing of a graphical object are also provided.

Claims

1. A method for rendering graphical data, the method comprising:

rendering an aliased version of an element of a graphical object in a two-dimensional field comprising a plurality of pixels;

sampling an edge portion of the aliased version of the element;

calculating a curve that approximates the edge portion and intersects a first subset of pixels;

determining the respective proportional areas of each pixel of the first subset of pixels that is located between the curve and the edge portion of the aliased version of the element; and

rendering an anti-aliased version of the edge portion based at least in part on the magnitudes of the respective proportional areas.

2. The method of claim 1, wherein the element of a graphical object is a polygon.

3. The method of claim 2, wherein the edge portion divides a second subset of pixels within the aliased version of the polygon from a third subset of pixels external to the aliased version of the polygon, and wherein the second and third subsets of pixels respectively comprise first and second colors different from one another.

4. The method of claim 3, wherein rendering the anti-aliased version of the edge portion comprises rendering at least one pixel of the first subset of pixels in a color blend of the first and second colors, and wherein the proportions of the first and second colors in the color blend for the at least one pixel of the first subset of pixels is based on the respective proportional area of the at least one pixel that is located between the curve and the edge portion of the aliased version of the polygon.

5. The method of claim 1, wherein calculating the curve comprises calculating a linear curve that approximates the edge portion of the aliased version of the element.

6. The method of claim 1, wherein the graphical object is a three-dimensional object.

7. The method of claim 1, wherein rendering the aliased version of the element comprises displaying the aliased version of the element on a display of a device.

8. The method of claim 1, wherein rendering the anti-aliased version of the edge portion comprises displaying the anti-aliased version of the edge portion on a display of a device.

9. A device comprising:

a housing;

a display disposed in the housing;

a memory device disposed in the housing, the memory device including executable application instructions stored therein; and

a processor disposed in the housing and configured to execute the application instructions stored in the memory device;

wherein the device is configured to render an aliased version of an element of a graphical object, to sample one or more edges of the aliased version of the element, and to render an anti-aliased version of the element based on the sampling of the one or more edges.

10. The device of claim 9, wherein the device is configured to render the anti-aliased version of the element on the display.

11. The device of claim 9, wherein the anti-aliased version of the element comprises a plurality of anti-aliased edges.

12. The device of claim 11, wherein each edge of the anti-aliased version of the element is anti-aliased.

13. The device of claim 9, wherein the device comprises a portable media player.

14. A method for rendering graphical data, the method comprising:

rendering aliased versions of two graphical elements in a two-dimensional field of pixels such that the two graphical elements include a common, aliased edge;

computing a curve that approximates the aliased edge between the two graphical elements; and

rendering anti-aliased versions of the two graphical elements based at least in part on adjusting a subset of pixels intersected by the curve.

15. The method of claim 14, comprising displaying the anti-aliased versions of the two graphical elements.

16. The method of claim 14, wherein adjusting a subset of pixels comprises rendering each pixel of the subset of pixels in a color different from those of any adjoining pixel that is not intersected by the curve.

17. The method of claim 16, wherein the rendered color of each pixel of the subset of pixels is a blend of colors from each of the two graphical elements.

18. The method of claim 17, wherein the rendered color of at least one pixel of the subset of pixels is a blend of two different colors of two pixels adjacent to the at least one pixel and not intersected by the curve.

19. The method of claim 14, wherein the two graphical elements comprise two polygons.

20. One or more tangible, machine-readable media having application instructions encoded thereon, the application instructions comprising:

instructions for rendering an aliased version of a plurality of polygons of one or more graphical objects in a two-dimensional field comprising a plurality of pixels, the aliased version comprising a plurality of jagged edges;

instructions for sampling a jagged edge portion of at least one polygon of the aliased version of the plurality of polygons;

instructions for calculating a curve that approximates the jagged edge portion and intersects a subset of pixels;

instructions for determining the respective proportional areas of each pixel of the subset of pixels that is located between the curve and the jagged edge portion; and

instructions for rendering an smoothed version of the edge portion based at least in part on the magnitudes of the respective proportional areas.

21. The one or more tangible, machine-readable media of claim 20, wherein the application instructions comprise instructions for outputting the aliased version of the plurality of polygons and/or instructions for outputting the smoothed version of the edge portion to a display.

22. The one or more tangible, machine-readable media of claim 20, wherein the one or more tangible, machine-readable media comprises a flash memory device.

23. The one or more tangible, machine-readable media of claim 20, wherein the one or more tangible, machine-readable media comprises a hard disk drive.