Anti-aliasing of a graphical object

• US 8,294,730 B2
• Filed: 09/04/2007
• Issued: 10/23/2012
• Est. Priority Date: 09/04/2007
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Tremblay, Christopher
• Primary Examiner(s): Hajnik, Daniel F
• Assistant Examiner(s): Prendergast, Roberta D
• Application Number:
  US11/899,033
• Publication Number:
  US 20090058880A1
• Time in Patent Office: 1,876 Days
• Field of Search: 345/426, 345/611, 345/613, 345/614, 345/615, 345/441, 345/442
• 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 5/70 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 using one or more processors of an apparatus to execute:

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

sampling, in a single sampling operation, an edge portion of the two-dimensional aliased version of the element in the two-dimensional field;

calculating a curve, using the one or more processors, based on the sampled edge portion that approximates but does not overlap the sampled 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 sampled edge portion of the aliased version of the element; and

rendering an anti-aliased version of the sampled 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 the three-dimensional graphical object is a polygon.

3. The method of claim 2, wherein the sampled 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 sampled 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 sampled 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 sampled edge portion of the aliased version of the element.

6. 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.

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

8. 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 in two dimensions an aliased version of an element of a three-dimensional graphical object in a two-dimensional field comprising a plurality of pixels, to sample, in a single sampling operation, one or more edges of the two-dimensional aliased version of the element in the two-dimensional field, to calculate one or more curves based on the sampled edge portion approximating but not overlapping the one or more sampled 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 and on the calculating of the one or more curves approximating the one or more sampled edges.

9. The device of claim 8, wherein the device is configured to render the anti-aliased version of the element on the display.

10. The device of claim 8, wherein the anti-aliased version of the element comprises a plurality of anti-aliased edges.

11. The device of claim 10, wherein each edge of the anti-aliased version of the element is anti-aliased.

12. The device of claim 8, wherein the device comprises a portable media player.

13. A method for rendering graphical data, the method comprising using one or more processors of an apparatus to execute:

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

sampling, in a single sampling operation, the common, two-dimensional aliased edge of the pair of three-dimensional graphical elements in the two-dimensional field of pixels;

computing a curve, using the one or more processors, based on the sampled, aliased edge that approximates but does not overlap the sampled, aliased edge between the pair of three-dimensional graphical elements; and

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

14. The method of claim 13, comprising displaying the anti-aliased versions of the pair of three-dimensional graphical elements.

15. The method of claim 13, 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.

16. The method of claim 15, wherein the rendered color of each pixel of the subset of pixels is a blend of colors from each of the pair of three-dimensional graphical elements.

17. The method of claim 16, 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.

18. The method of claim 13, wherein the pair of three-dimensional graphical elements comprise two polygons.

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

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

instructions for sampling, in a single sampling operation, a jagged edge portion of at least one polygon of the two-dimensional aliased version of the plurality of polygons in the two-dimensional field;

instructions for calculating a curve based on the sampled, jagged edge portion that approximates but does not overlap the sampled, 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 sampled, jagged edge portion; and

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

20. The one or more non-transitory, tangible, machine-readable media of claim 19, 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 sampled, jagged edge portion to a display.

21. The one or more non-transitory, tangible, machine-readable media of claim 19, wherein the one or more non-transitory, tangible, machine-readable media comprises a flash memory device.

22. The one or more non-transitory, tangible, machine-readable media of claim 19, wherein the one or more non-transitory, tangible, machine-readable media comprises a hard disk drive.