METHOD AND SYSTEM FOR REDUCING EFFECTS OF UNDESIRED SIGNALS IN AN INFRARED IMAGING SYSTEM

• US 20080193043A1
• Filed: 04/21/2008
• Published: 08/14/2008
• 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 7,613,358 B2
• Time in Patent Office: Days
• US Class Current: 382/275
• 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) a light-permeable surface having a processing side and an interactive side, the interactive side being configured enable a physical object to be disposed on or adjacent to the interactive side, the processing side being opposite to the interactive side;

(b) a desired infrared light source disposed on the processing side of the light-permeable surface, the desired infrared light source selectively emitting infrared light that is transmitted through the light-permeable surface to the interactive side and reflected back through the light-permeable surface by the physical object that is disposed on or adjacent to the interactive side of the light-permeable surface;

(c) an image capture device disposed on the processing side of the light-permeable surface, the image capture device sensing infrared light passing through the light permeable surface and imaging the interactive display surface to detect the physical object and its location;

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

(e) 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;

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

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

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

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

(v) 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 the first side of the light-permeable surface 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 first side of the light permeable surface 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 first side of the light-permeable surface;

(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. The system of claim 1, further comprising a projector positioned on the processing side of the light-permeable surface such that light from the projector is directed onto the light-permeable surface and used to present images visible on the interactive side of the light-permeable surface with which the physical object can interact.

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

(a) a light-permeable surface having a processing side and an interactive side, the interactive side being configured to enable a physical object to be disposed on or adjacent to the interactive side, the processing side being opposite to the interactive side;

(b) an image capture device disposed on the processing side of the light-permeable surface, the image capture device sensing infrared light passing through the light permeable surface and imaging the interactive display surface to detect the physical object and its location, the image capture device being configured to generate an image capture signal;

(c) a desired infrared light source disposed on the processing side of the light-permeable surface, the desired infrared light source selectively emitting infrared light that is transmitted through the light-permeable surface to the interactive side and reflected back through the light-permeable surface by the physical object that is disposed on or adjacent to the interactive side of the light-permeable surface;

(d) an infrared light source controller configured to;

(i) receive the image capture signal; and

(ii) 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;

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

(f) 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;

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

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

(iii) 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.

7. The system of claim 6, 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 the first side of the light-permeable surface 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 first side of the light-permeable surface during the second image capture interval while the desired infrared light source was deactivated.

8. The system of claim 7, 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 first side of the light-permeable surface;

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

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

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.

9. The system of claim 6, 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.

10. The system of claim 6, further comprising a projector positioned on the processing side of the light-permeable surface such that light produced by the projector is directed onto the light-permeable surface and used to present images visible on the interactive side of the light-permeable surface with which the physical object can interact.