Method and System for Reducing Effects of Undesired Signals in an Infrared Imaging System

• US 20090262070A1
• Filed: 06/26/2009
• Published: 10/22/2009
• Est. Priority Date: 06/16/2004
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Wilson, Andrew D.
• Granted Patent: US 8,165,422 B2
• Time in Patent Office: Days
• US Class Current: 345/156
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen
• CPC Class Codes: G06V 40/107 Static hand or arm
• CPC Class Codes: H04N 23/56 provided with illuminating means
• CPC Class Codes: H04N 5/33 Transforming infrared radiation cameras or camera modules for generating image signals from infrared radiation H04N23/20; circuitry of SSIS for transforming infrared radiation into image signals H04N25/20

Abstract

Effects of undesired infrared light are reduced in an imaging system using an infrared light source. The desired infrared light source is activated and a first set of imaging data is captured during a first image capture interval. The desired infrared light source is then deactivated, and a second set of image data is captured during a second image capture interval. A composite set of image data is then generated by subtracting from first values in the first set of image data corresponding second values in the second set of image data. The composite set of image data thus includes a set of imaging where data all infrared signals are collected, including both signals resulting from the IR source and other IR signals, from which is subtracted imaging in which no signals result from the IR course, leaving image data including signals resulting only from the IR source.

Claims

1. A system for providing input to an application that is being executed, comprising:

a desired infrared light source, the desired infrared light source selectively emitting infrared light that is transmitted to a physical object and reflected back by the physical object;

an image capture device, the image capture device sensing infrared light and imaging a volume to detect the physical object and its location;

a processor in communication with the desired infrared light source and the image capture device; and

a memory in communication with the processor, the memory storing data and machine instructions that cause the processor to carry out a plurality of functions, including;

activating the desired infrared light source during a first image capture interval;

capturing a first set of image data during the first image capture interval with the image capture device;

deactivating the desired infrared light source during a second image capture interval;

capturing a second set of image data during the second image capture interval with the image capture device; and

generating a composite set of image data by subtracting from first values in the first set of image data corresponding second values in the second set of image data, an effect of infrared light captured by the image capture device but not emitted by the desired infrared source being substantially eliminated in the composite set of data.

2. The system of claim 1, wherein the first values in the first set of image data represent an intensity of infrared light captured by the image capture device for a plurality of points across a plane of the volume during the first image capture interval while the desired infrared light source was activated, and the second values in the set of image data represent an intensity of infrared light captured by the image capture device for the plurality of points across the plane of the volume during the second image capture interval while the desired infrared light source was deactivated.

3. The system of claim 1, wherein the machine instructions stored in the memory further cause the processor to subtract from first values in the first set of image data, corresponding second values in the second set of image data, as defined by:

D(x,y)=I_ON(x,y)−

I_OFF(x,y) where;

(a) x,y represents a coordinate location of a point on the plane;

(b) I_ON (x,y) represents an intensity of infrared light detected by the image capture device during the first image capture interval at the point x,y;

(c) I_OFF(x,y) represents an intensity of infrared light detected by the image capture device during the second image capture interval at the point x,y; and

(d) D(x,y) represents a net intensity of infrared light at point x,y when the intensity of the infrared light captured at the point x,y during the second image capture interval is subtracted from the intensity of the infrared light captured at the point x, y during the first image capture interval.

4. The system of claim 1, wherein the machine instructions stored in the memory further cause the processor to use the infrared light reflected by the physical object to recognize a characteristic of the physical object.

5. A system for providing input to an application that is being executed, comprising:

an image capture device, the image capture device sensing infrared light and imaging a volume to detect a physical object and its location, the image capture device being configured to generate an image capture signal;

a desired infrared light source, the desired infrared light source selectively emitting infrared light that is transmitted to the physical object and reflected back by the physical object;

an infrared light source controller configured to;

receive the image capture signal; and

selectively actuate the desired infrared light source in response to receipt of the image capture signal, such that the desired infrared light source is activated on receipt of a first image capture signal indicating a first image capture interval and deactivated on receipt of a second image capture signal indicating a second image capture interval;

a processor in communication infrared light source and the image capture device; and

a memory in communication with the processor, the memory storing data and machine instructions that cause the processor to carry out a plurality of functions, including;

capturing a first set of image data with the image capture device during the first image capture interval;

capturing a second set of image data with the image capture device during the second image capture interval; and

generating a composite set of image data by subtracting from first values in the first set of image data, corresponding second values in the second set of image data, any effect of extraneous infrared light captured by the image capture device being substantially compensated in the composite set of image data.

6. The system of claim 5, wherein the first values in the first set of image data represent an intensity of infrared light captured by the -image capture device for a plurality of points across a plane of the volume during the first image capture interval while the desired infrared light source was activated, and the second values in the set of image data represent an intensity of infrared light captured for the plurality of points across the plane of the volume during the second image capture interval while the desired infrared light source was deactivated.

7. The system of claim 6, wherein the machine instructions stored in the memory further cause the processor to subtract from first values in the first set of image data, corresponding second values in the second set of image data, as defined by:

D(x,y)=I_ON(x,y)−

I_OFF(x,y) where;

(a) x,y represents a coordinate location of a point on the plane;

(b) I_ON (x,y) represents an intensity of infrared light detected during the first image capture interval at the point xy;

(c) I_OFF(x,y) represents an intensity of infrared light detected during the second image capture interval at the point xy; and

(d) D(x,y) represents a net intensity of infrared light at the point x,y when the intensity of the infrared light captured at the point x,y during the second image capture interval is subtracted from the intensity of the infrared light captured at the point x,y during the first image capture interval.

8. The system of claim 5, wherein the machine instructions stored in the memory further cause the processor to use the infrared light reflected by the physical object to recognize a characteristic of the physical object.