Input classification for multi-touch systems

1. A computer implemented method, comprising:

receiving data describing a first region of contact with a touch sensitive display and a second region of contact with the touch sensitive display;

determining at least one characteristic of the first region of contact;

based on the at least one characteristic of the first region of contact, determining that the first region of contact corresponds to intended touch input provided by a user's body part or stylus;

determining at least one characteristic of the second region of contact;

based on the at least one characteristic of the second region of contact, determining that the second region of contact corresponds to incidental touch input provided by a user's resting body part comprising:

determining a perimeter corresponding to the second region of contact:

determining an area corresponding to the second region of contact;

determining a ratio of the determined perimeter to the determined area;

comparing the determined ratio to a threshold;

based on comparing the determined ratio to the threshold, determining that the determined ratio is greater than the threshold;

based on the determination that the determined ratio is greater than the threshold, determining that the second region of contact corresponds to incidental touch input; and

based on the determination that the first region of contact corresponds to intended touch input and the second region of contact corresponds to incidental touch input, updating the touch sensitive display by responding to the first region of contact as touch input while ignoring the second region of contact.

2. The method of claim 1 :

wherein determining the at least one characteristic of the first region of contact comprises determining a first area of the first region of contact;

wherein determining that the first region of contact corresponds to intended touch input comprises determining that the first region of contact corresponds to intended touch input based on the first area of the first region of contact;

wherein determining the at least one characteristic of the second region of contact comprises determining a second area of the second region of contact; and

wherein determining that the second region of contact corresponds to incidental touch input comprises determining that the second region of contact corresponds to incidental touch input based on the second area of the second region of contact.

3. The method of claim 2 :

wherein determining that the first region of contact corresponds to intended touch input based on the first area of the first region of contact comprises:

comparing the first area of the first contact region to a threshold;

based on comparing the first area of the first contact region to the threshold, determining that the first area is less than the threshold; and

based on the determination that the first area is less than the threshold, determining that the first region of contact corresponds to intended touch input; and

wherein determining that the second region of contact corresponds to incidental touch input based on the second area of the second region of contact comprises:

comparing the second area of the second contact region to the threshold;

based on comparing the second area of the second contact region to the threshold, determining that the second area is greater than the threshold; and

based on the determination that the second area is greater than the threshold, determining that the second region of contact corresponds to incidental touch input.

4. The method of claim 1 :

wherein determining the at least one characteristic of the second region of contact comprises determining an ellipse that surrounds the second region of contact, the ellipse having a major axis and a minor axis; and

wherein determining that the second region of contact corresponds to incidental touch input comprises determining that the second region of contact corresponds to incidental touch input based on the determined ellipse.

5. The method of claim 4 , wherein determining that the second region of contact corresponds to incidental touch input based on the determined ellipse comprises:

determining a ratio of the major axis of the ellipse to the minor axis of the ellipse;

comparing the determined ratio to a threshold;

based on comparing the determined ratio to the threshold, determining that the determined ratio is greater than the threshold; and

based on the determination that the determined ratio is greater than the threshold, determining that the second region of contact corresponds to incidental touch input.

6. The method of claim 1 , wherein determining that the second region of contact corresponds to incidental touch input comprises:

determining an area of the second region of contact;

determining an ellipse that surrounds the second region of contact, the ellipse having a major axis and a minor axis;

determining a first ratio of the major axis of the ellipse to the minor axis of the ellipse;

determining a total capacitance corresponding to the second region of contact; and

determining that the second region of contact corresponds to incidental touch input based on the determined area of the second region of contact, the first ratio of the major axis of the ellipse to the minor axis of the ellipse, and the total capacitance corresponding to the second region of contact.

7. The method of claim 1 :

wherein determining the at least one characteristic of the second region of contact comprises determining a capacitance corresponding to the second region of contact; and

wherein determining that the second region of contact corresponds to incidental touch input comprises determining that the second region of contact corresponds to incidental touch input based on the determined capacitance.

8. The method of claim 7 , wherein determining that the second region of contact corresponds to incidental touch input based on the determined capacitance comprises:

comparing the determined capacitance of the second contact region to a threshold;

based on comparing the determined capacitance of the second contact region to the threshold, determining that the capacitance is greater than the threshold; and

based on the determination that the capacitance is greater than the threshold, determining that the second region of contact corresponds to incidental touch input.

9. A system comprising:

one or more computers configured to perform operations comprising:

receiving data describing a first region of contact with a touch sensitive display and a second region of contact with the touch sensitive display;

determining at least one characteristic of the first region of contact;

based on the at least one characteristic of the first region of contact, determining that the first region of contact corresponds to intended touch input provided by a user's body part or stylus;

determining at least one characteristic of the second region of contact;

based on the at least one characteristic of the second region of contact, determining that the second region of contact corresponds to incidental touch input provided by a user's resting body part comprising:

determining a perimeter corresponding to the second region of contact:

determining an area corresponding to the second region of contact:

determining a ratio of the determined perimeter to the determined area;

comparing the determined ratio to a threshold;

based on comparing the determined ratio to the threshold, determining that the determined ratio is greater than the threshold;

based on the determination that the determined ratio is greater than the threshold, determining that the second region of contact corresponds to incidental touch input; and

based on the determination that the first region of contact corresponds to intended touch input and the second region of contact corresponds to incidental touch input, updating the touch sensitive display by responding to the first region of contact as touch input while ignoring the second region of contact.

10. The system of claim 9 :

wherein determining the at least one characteristic of the first region of contact comprises determining a first area of the first region of contact;

wherein determining that the first region of contact corresponds to intended touch input comprises determining that the first region of contact corresponds to intended touch input based on the first area of the first region of contact;

wherein determining the at least one characteristic of the second region of contact comprises determining a second area of the second region of contact; and

wherein determining that the second region of contact corresponds to incidental touch input comprises determining that the second region of contact corresponds to incidental touch input based on the second area of the second region of contact.

11. The system of claim 10 :

wherein determining that the first region of contact corresponds to intended touch input based on the first area of the first region of contact comprises:

comparing the first area of the first contact region to a threshold;

based on comparing the first area of the first contact region to the threshold, determining that the first area is less than the threshold; and

based on the determination that the first area is less than the threshold, determining that the first region of contact corresponds to intended touch input; and

wherein determining that the second region of contact corresponds to incidental touch input based on the second area of the second region of contact comprises:

comparing the second area of the second contact region to the threshold;

based on comparing the second area of the second contact region to the threshold, determining that the second area is greater than the threshold; and

based on the determination that the second area is greater than the threshold, determining that the second region of contact corresponds to incidental touch input.

12. The system of claim 9 :

wherein determining the at least one characteristic of the second region of contact comprises determining an ellipse that surrounds the second region of contact, the ellipse having a major axis and a minor axis; and

wherein determining that the second region of contact corresponds to incidental touch input comprises determining that the second region of contact corresponds to incidental touch input based on the determined ellipse.

13. The system of claim 12 , wherein determining that the second region of contact corresponds to incidental touch input based on the determined ellipse comprises:

determining a ratio of the major axis of the ellipse to the minor axis of the ellipse;

comparing the determined ratio to a threshold; based on comparing the determined ratio to the threshold, determining that the determined ratio is greater than the threshold; and

based on the determination that the determined ratio is greater than the threshold, determining that the second region of contact corresponds to incidental touch input.

14. The system of claim 9 , wherein determining that the second region of contact corresponds to incidental touch input comprises:

determining an area of the second region of contact;

determining an ellipse that surrounds the second region of contact, the ellipse having a major axis and a minor axis;

determining a first ratio of the major axis of the ellipse to the minor axis of the ellipse;

determining a total capacitance corresponding to the second region of contact; and

determining that the second region of contact corresponds to incidental touch input based on the determined area of the second region of contact, the first ratio of the major axis of the ellipse to the minor axis of the ellipse, and the total capacitance corresponding to the second region of contact.

15. The system of claim 9 :

wherein determining the at least one characteristic of the second region of contact comprises determining a capacitance corresponding to the second region of contact; and

wherein determining that the second region of contact corresponds to incidental touch input comprises determining that the second region of contact corresponds to incidental touch input based on the determined capacitance.

16. The system of claim 15 , wherein determining that the second region of contact corresponds to incidental touch input based on the determined capacitance comprises:

comparing the determined capacitance of the second contact region to a threshold;

based on comparing the determined capacitance of the second contact region to the threshold, determining that the capacitance is greater than the threshold; and

based on the determination that the capacitance is greater than the threshold, determining that the second region of contact corresponds to incidental touch input.