# US 2013/0155022 A1 · Multi-touch input discrimination > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0155022 A1 - Document ID: US20130155022A1 - Status: Published application - Kind: A1 - Application number: 13/769,045 - Filed: 2013-02-15 - Published: 2013-06-20 - Earliest claimed: 2007-01-03 - Assignees: Apple Inc. - Inventors: Wayne Carl WESTERMAN - Web page: https://patentgrep.com/patent/US20130155022A1 ## CPC - G06F 3/04182: {Filtering of noise external to the device and not generated by digitiser components} - G06F 3/04186: {Touch location disambiguation} - G06V 40/107: {Static hand or arm} - G06F 3/044: by capacitive means - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - G06V: IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING ## Abstract Techniques for identifying and discriminating between different input patterns to a multi-touch touch-screen device are described. By way of example, large objects hovering a short distance from the touch-surface (e.g., a cheek, thigh or chest) may be identified and distinguished from physical contacts to the surface. In addition, rough contacts due to, for example, ears and earlobes, may be similarly identified and distinguished from contacts due to fingers, thumbs, palms and finger clasps. ## Claims ### Claim 1 A method to identify an object that is hovering above but not in contact with a multi-touch touch-surface, comprising: obtaining a proximity image having a plurality of pixels; generating a far-field image from the proximity image, the far-field image having a plurality of pixels; identifying background pixels in the proximity image; generating a far-field measure value by combining pixel values in the far-field image that correspond to background pixels in the proximity image; determining that an object is hovering above a multi-touch touch-surface if the far-field measure value is above a specified threshold; triggering a proximity sensor when an object is proximate the proximity sensor; and controlling an operation of a device if an object is determined to be hovering above the multi-touch touch-surface and the proximity sensor is triggered. ### Claim 2 (depends on 1) The method of claim 1, wherein the act of generating a far-field image comprises: subtracting a noise value from each pixel value in the proximity image to generate a first intermediate image having a plurality of pixels; saturating pixel values in the first intermediate image to generate a second intermediate image having a plurality of pixels; and filtering the second intermediate image to generate the far-field image. ### Claim 3 (depends on 2) The method of claim 2, wherein the noise value is a constant value for all pixels in the proximity image. ### Claim 4 (depends on 2) The method of claim 2, wherein the noise value is unique to each pixel in the proximity image. ### Claim 5 (depends on 2) The method of claim 2, wherein the act of saturating comprises changing each pixel value in the first intermediate image that is above a first specified value to a second specified value. ### Claim 6 (depends on 2) The method of claim 2, wherein the act of filtering comprises averaging at least two spatially adjacent pixels in the second intermediate image. ### Claim 7 (depends on 6) The method of claim 6, wherein the act of averaging comprises performing a weighted average. ### Claim 8 (depends on 1) The method of claim 1, wherein the act of identifying background pixels comprises segmenting the proximity image to identify background pixels and non-background pixels. ### Claim 9 (depends on 1) The method of claim 1, wherein the act of combining comprises linearly combining pixel values identified as background pixels. ### Claim 10 (depends on 1) The method of claim 1, wherein the act of combining comprises non-linearly combining pixel values identified as background pixels. ### Claim 11 (depends on 10) The method of claim 10, wherein the act of non-linearly combining pixel values comprises non-linearly amplifying pixel values identified as background pixels. ### Claim 12 (depends on 1) The method of claim 1, wherein the act of generating a far-field measure includes weighting each background pixel value with a touch-surface location factor. ### Claim 13 (depends on 12) The method of claim 12, wherein the touch-surface location factor associated with a first collection of pixels has a lower value than the touch-surface location factor associated with a second collection of pixels. ### Claim 14 (depends on 13) The method of claim 13, wherein the first collection of pixels are associated with pixels adjacent to an edge of the proximity image. ### Claim 15 (depends on 1) The method of claim 1, wherein the act of controlling comprises changing the operation state of the device. ### Claim 16 (depends on 1) The method of claim 1, wherein the act of controlling comprises placing the device into a low-power state. ### Claim 17 (depends on 1) The method of claim 1, wherein the act of controlling comprises ignoring the identified hovering object. ### Claim 18 (depends on 1) The method of claim 1, wherein the device comprises a mobile telephone. ### Claim 19 (depends on 1) The method of claim 1, wherein the device comprises one of the devices selected from the group consisting of: tablet computer system, a hand-held computer system, a portable music player system, and a portable video player system. ### Claim 20 (depends on 1) A program storage device, readable by a programmable control device, comprising instructions stored thereon for causing the programmable control device to perform the method of claim 1. ### Claim 21 (depends on 1) A portable electronic device, comprising: a multi-touch input touch-surface; means for receiving a proximity image from the multi-touch input touch-surface; a proximity sensor for sensing proximity of an object; and processing means for performing acts in accordance with claim 1. ### Claim 22 (depends on 21) The device in accordance with claim 21, wherein the portable electronic device comprises a mobile telephone. ### Claim 23 (depends on 21) The device in accordance with claim 21, wherein the portable electronic device is selected from the group consisting of a tablet computer system, a hand-held computer system, a portable music player system, and a portable video player system. ### Claim 24 (depends on 1) The method of claim 1, wherein generating the far-field measure value includes amplifying pixel values which are below a given value. ### Claim 25 (depends on 2) The method of claim 2, wherein saturating the pixel values in the first intermediate image includes setting a saturation limit value to be less than the peak value from fingers or thumbs hovering within approximately 1 to 2 millimeters of the touch surface, and setting pixel values which exceed the saturation limit value to be equal to the saturation limit value. ### Claim 26 (depends on 1) The method of claim 1, wherein the step of generating the far field image comprises saturating pixel values in the proximity image. ### Claim 27 (depends on 26) The method of claim 26, wherein saturating the pixel values includes setting a saturation limit value to be less than the peak value from fingers or thumbs hovering over the touch surface, and setting pixel values which exceed the saturation limit value to be equal to the saturation limit value. ### Claim 28 (depends on 27) The method of claim 27, further including subtracting a noise value from the proximity image prior to saturating and then saturating the noise subtracted proximity image. ### Claim 29 (depends on 26) The method of claim 26, wherein saturating the pixel values includes setting a saturation limit value to be between +3 and +6 standard deviations of noise associated with an initial far-field image. ### Claim 30 (depends on 1) The method of claim 1, the proximity image including patch pixels corresponding to an object in contact with the touch-surface and the background pixels corresponding to other than patch pixels. ### Claim 31 (depends on 1) The method of claim 1 further comprising: identifying an pixel patch in contact with the multi-touch touch-surface; and controlling an operation of the device if an object is determined to be hovering above the multi-touch touch-surface, the proximity sensor is triggered and a pixel patch is identified as being in contact with the multi-touch touch-surface. ### Claim 32 (depends on 31) The method of claim 31, wherein the proximity sensor is disposed beyond an edge portion of the multi-touch touch-surface. ### Claim 33 (depends on 32) The method of claim 32, wherein the proximity sensor comprises an infrared-reflectance sensor. ### Claim 34 (depends on 32) The method of claim 32, wherein the proximity sensor comprises capacitance-sensitive electrode strips. ### Claim 35 (depends on 31) The method of claim 31, wherein the proximity sensor is disposed beyond an edge portion of the multi-touch touch-surface. ### Claim 36 (depends on 35) The method of claim 35, wherein the proximity sensor comprises an infrared-reflectance sensor. ### Claim 37 (depends on 32) The method of claim 32, wherein the proximity sensor comprises capacitance-sensitive electrode strips. ### Claim 38 (depends on 31) A portable electronic device, comprising: a multi-touch input touch-surface; means for receiving a proximity image from the multi-touch input touch-surface; a proximity sensor disposed outside of the multi-touch input touch-surface for sensing proximity of an object to the electronic device; and processing means for performing acts in accordance with claim 31. ### Claim 39 (depends on 38) The portable electronic device as recited in claim 38, wherein the proximity sensor comprises an infrared-reflectance sensor. ### Claim 40 (depends on 38) The portable electronic device as recited in claim 38, wherein the proximity sensor comprises capacitance-sensitive electrode strips.