Detecting and tracking touch on an illuminated surface using a mean-subtracted image
AssigneeTexas Instruments Incorporated
InventorVinay Sharma
Life of this patent
Estimating the term…
Abstract
A method for touch detection performed by a touch processor in an optical touch detection system is provided that includes receiving an image of an illuminated surface included in the optical touch detection system, wherein the image is captured by a camera included in the optical touch detection system, subtracting a background model from the image to generate a mean-subtracted image, identifying a set of candidate touch locations in the mean-subtracted image, classifying the candidate touch locations in the set of candidate touch locations to generate a set of validated candidate touch locations, and outputting a set of final touch locations determined from the set of validated candidate touch locations.
Claims18
A method for touch detection performed by a touch processor in an optical touch detection system, the method comprising:
- receiving, with one or more processors, an image of an illuminated surface included in the optical touch detection system, wherein the image is captured by a camera included in the optical touch detection system;
- subtracting, with the one or more processors, a background model from the image to generate a mean-subtracted image;
- filtering the mean-subtracted image with a filter having zero mean with coefficients of a same sign in a central region of the filter surrounded by coefficients of an opposite sign such that a size of the central region corresponds to an expected size of a finger touch;
- identifying, with the one or more processors, local extrema in the filtered mean-subtracted image to generate a set of candidate touch locations;
- classifying, with the one or more processors, the candidate touch locations by comparing each of the local extrema to one or more detection thresholds to generate a set of validated candidate touch locations;
- and
- outputting, with the one or more processors, a set of final touch locations determined from the set of validated candidate touch locations.
An optical touch detection system configured for touch detection, the system comprising:
- an illuminated surface;
- a camera positioned to capture images of the illuminated surface;
- and
- one or more processors configured to:
- receive an image of the illuminated surface captured by the camera;
- subtract a background model from the image to generate a mean-subtracted image;
- identify local extrema in the mean-subtracted image to generate a set of candidate touch locations;
- classify the candidate touch locations in the set of candidate touch locations by comparing each of the local extrema to one or more detection thresholds to generate a set of validated candidate touch locations;
- and
- output a set of final touch locations determined from the set of validated candidate touch locations.
A non-transitory computer readable medium storing software instructions that, when executed by a touch processor included in an optical touch detection system, cause the optical touch detection system to:
- receive an image of an illuminated surface included in the optical touch detection system, wherein the image is captured by a camera included in the optical touch detection system;
- subtract a background model from the image to generate a mean-subtracted image;
- identify local extrema in the mean-subtracted image to generate a set of candidate touch locations;
- classify the candidate touch locations in the set of candidate touch locations by comparing each of the local extrema to one or more detection thresholds to generate a set of validated candidate touch locations;
- and output a set of final touch locations determined from the set of validated candidate touch locations.
Dependencies are inferred from the claim text.