Bottom-up watershed dataflow method and region-specific segmentation based on historic data to identify patches on a touch sensor panel

• US 10,175,805 B2
• Filed: 03/25/2011
• Issued: 01/08/2019
• Est. Priority Date: 06/13/2007
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Westerman, Wayne Carl, Strickon, Joshua A.
• Primary Examiner(s): Boyd, Jonathan
• Application Number:
  US13/072,623
• Publication Number:
  US 20110169763A1
• Time in Patent Office: 2,846 Days
• Field of Search: 345156, 345173-178, 178 18- 20
• CPC Class Codes: G06F 3/038 Control and interface arrangements therefor, e.g. drivers or device-embedded control circuitry
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• CPC Class Codes: G06F 3/0488 using a touch-screen or digitiser, e.g. input of commands through traced gestures
• CPC Class Codes: G06T 7/11 Region-based segmentation
• CPC Class Codes: G06T 7/155 involving morphological operators

Abstract

The application of a watershed algorithm to pixels and their touch values obtained from a scan of a touch sensor panel to determine patches corresponding to images of touch is disclosed. Prior to applying the watershed algorithm, background pixels having little or no touch values can be eliminated. A primary merge algorithm can then merge adjacent patches together when the saddle point between them is shallow as compared to the peak represented by the patches. However, if two candidate patches for merging have a total number of pixels below a certain threshold, these two patches may not be merged under the assumption that the patches might have been caused by different fingertips. Conversely, if two candidate patches for merging have a total number of pixels above a certain threshold, these two patches can be merged under the assumption that the patches were caused by a single thumb or palm.

Claims

1. A method for merging touch patches in an image of touch generated on a touch sensor panel, comprising:

identifying a plurality of touch patches, each touch patch comprising a plurality of touch pixels;

identifying a saddle point between two non-overlapping touch patches, the saddle point having an associated touch value; and

merging the two touch patches when;

the touch value of the saddle point is within a predetermined magnitude of a peak touch value of at least one of the two touch patches, wherein determining whether the touch value of the saddle point is within a predetermined magnitude of a peak touch value of at least one of the two touch patches includes determining a ratio of the touch value of the saddle point to at least one peak touch value of the two touch patches, and

a number of touch pixels in at least one of the two touch patches is greater than a predetermined threshold.

2. The method of claim 1, wherein the touch value of the saddle point is a maximum touch value of a touch pixel among a group of touch pixels along a shared border between the two touch patches.

3. The method of claim 1, further comprising lowering the predetermined threshold if one of the two touch patches is smaller than the other and the smaller patch is substantially aligned with the larger patch.

4. The method of claim 3, further comprising determining whether the smaller patch is substantially aligned with the larger patch by determining whether x-coordinates of the patches are within a predetermined range.

5. A non-transitory computer-readable storage medium storing program code for merging touch patches in an image of touch generated on a touch sensor panel, the program code for causing performance of a method comprising:

identifying a plurality of touch patches, each touch patch comprising a plurality of touch pixels;

identifying a saddle point between two non-overlapping touch patches, the saddle point having an associated touch value; and

merging the two touch patches when;

the touch value of the saddle point is within a predetermined magnitude of a peak touch value of at least one of the two touch patches, wherein determining whether the touch value of the saddle point is within a predetermined magnitude of a peak touch value of at least one of the two touch patches includes determining a ratio of the touch value of the saddle point to at least one peak touch value of the two touch patches, and

a number of touch pixels in at least one of the two touch patches is greater than a predetermined threshold.

6. The non-transitory computer-readable storage medium of claim 5, wherein the touch value of the saddle point is a maximum touch value of a touch pixel among a group of touch pixels along a shared border between the two touch patches.

7. The non-transitory computer-readable storage medium of claim 5, the method further comprising lowering the predetermined threshold if one of the two patches is smaller than the other, and the smaller patch is substantially aligned with the larger patch.

8. The non-transitory computer-readable storage medium of claim 7, the method further comprising determining whether the smaller patch is substantially aligned with the larger patch by determining whether x-coordinates of the patches are within a predetermined range.

9. A touch-sensitive device comprising the non-transitory computer-readable storage medium of claim 5.

10. A touch-sensitive device, comprising:

a touch sensor panel; and

a panel processor for merging touch patches in an image of touch generated on the touch sensor panel, the panel processor programmed for;

identifying a plurality of touch patches, each touch patch comprising a plurality of touch pixels,

identifying a saddle point between two non-overlapping touch patches, the saddle point having an associated touch value, and

merging the two touch patches when;

the touch value of the saddle point is within a predetermined magnitude of a peak touch value of at least one of the two touch patches, wherein determining whether the touch value of the saddle point is within a predetermined magnitude of a peak touch value of at least one of the two touch patches includes determining a ratio of the touch value of the saddle point to at least one peak touch value of the two touch patches, and

a number of touch pixels in at least one of the two touch patches is greater than a predetermined threshold.

11. The touch-sensitive device of claim 10, wherein the touch value of the saddle point is a maximum touch value of a touch pixel among a group of touch pixels along a shared border between the two touch patches.

12. The touch-sensitive device of claim 10, the panel processor further programmed for lowering the predetermined threshold if one of the two touch patches is smaller than the other, and the smaller patch is substantially aligned with the larger patch.

13. The touch-sensitive device of claim 12, the panel processor further programmed for determining whether the smaller patch is substantially aligned with the larger patch by determining whether x-coordinates of the patches are within a predetermined range.