Method and system for reducing effects of undesired signals in an infrared imaging system

• US 20050281475A1
• Filed: 06/16/2004
• Published: 12/22/2005
• 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 7,593,593 B2
• Time in Patent Office: Days
• US Class Current: 382/254
• 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 23/20 for generating image signals from infrared radiation only
• 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 method for reducing an effect of an undesired infrared light source in an imaging system using a desired infrared light source, the method comprising the steps of:

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

(b) capturing a first set of image data during the first image capture interval;

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

(d) capturing a second set of image data during the second image capture interval; and

(e) producing 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.

2. The method of claim 1, further comprising the step of controlling activation of the desired infrared light source with an image capture device, such that an image capture signal generated by the image capture device causes the desired infrared light source to be activated during the first image capture interval and deactivated during the second image capture interval.

3. The method of claim 2, further comprising the steps of:

(a) positioning the desired infrared light source on a first side of a light-permeable surface to direct infrared light on a physical object disposed adjacent an opposite side of the light-permeable surface; and

(b) positioning the image capture device on the first side of a light-permeable surface to capture infrared light that was produced by the desired infrared light source and reflected by the physical object.

4. The method of claim 3, wherein the first values in the first set of image data represent an intensity of infrared light captured 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.

5. The method of claim 4, wherein the subtracting from the first values in the first set of image data corresponding second values in the second set of image data is 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 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.

6. The method of claim 3, further comprising the step of communicating the composite set of image data to an image processing system.

7. The method of claim 6, further comprising the step of using the infrared light reflected by the physical object to recognize a characteristic of the physical object.

8. The method of claim 3, further comprising the step of positioning a projector on the first side of the light-permeable surface such that light from the projector directed onto the light-permeable surface is used to present images visible on the opposite side of the light-permeable surface with which the physical object can interact.

9. A method for reducing an effect of an undesired infrared light source in an imaging system using a desired infrared light source, comprising the steps of:

(a) selectively coordinating activation of the desired infrared light source with an image signal generated by an image capture device;

(b) activating the desired infrared light source when the image signal indicates initiation of a first image capture interval;

(c) capturing a first set of image data during the first image capture interval;

(d) deactivating the desired infrared light source when the image signal indicates initiation of a second image capture interval;

(e) capturing a second set of image data during the second image capture interval;

(f) 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; and

(g) communicating the composite set of image data to an image processing system.

10. The method of claim 9, further comprising the steps of:

(a) positioning the desired infrared light source on a first side of a light-permeable surface to direct infrared light on a physical object disposed adjacent an opposite side of the light-permeable surface; and

(b) positioning the image capture device on the first side of a light-permeable surface to capture infrared light from the desired infrared light source that is reflected by the physical object.

11. The method of claim 10, wherein the first values in the first set of image data represent an intensity of infrared light captured 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 a correspondingly 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.

12. The method of claim 11, wherein the step of subtracting from first values in the first set of image data corresponding second values in the second set of image data is 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) 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.

13. The method of claim 10, further comprising the step of using the infrared light reflected by the physical object to recognize a characteristic of the physical object.

14. The method of claim 10, further comprising the step of positioning a projector on the first side of the light-permeable surface such that light from the projector is directed onto the light-permeable surface to present images visible on the opposite side of the light-permeable surface with which the physical object can interact.

15. A method for capturing image data for a physical object disposed on or adjacent to a light-permeable surface using a desired infrared light source and an image capture device, comprising the steps of:

(a) positioning the desired infrared light source on a first side of the light-permeable surface to direct infrared light toward the physical object;

(b) positioning the image capture device on the first side of a light-permeable surface to capture infrared light cast by the desired infrared light source and reflected by the physical object;

(c) activating the desired infrared light source when the image signal indicates initiation of a first image capture interval;

(d) capturing a first set of image data during the first image capture interval;

(e) deactivating the desired infrared light source when the image signal indicates initiation of a second image capture interval;

(f) capturing a second set of image data during the second image capture interval; and

(g) 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.

16. The method of claim 15, further comprising the step of controlling activation of the desired infrared light source with the image capture device, such that an image capture signal generated by the image capture device causes the desired infrared light source to be activated during the first image capture interval and deactivated during the second image capture interval.

17. The method of claim 15, wherein the first values in the first set of image data represent an intensity of infrared light captured 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.

18. The method of claim 17, wherein the step of subtracting from first values in the first set of image data, corresponding second values in the second set of image data is defined by:

D(x,y)=I_ON(x,y)−

I_OFF(x,y)

where;

(a) xy 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 a point x,y;

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

(d) D(x,y) represents a net intensity of infrared light at a 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.

19. The method of claim 15, further comprising the step of communicating the composite set of image data to an image processing system.

20. The method of claim 19, further comprising the step of using the infrared light reflected by the physical object to recognize a characteristic of the physical object.

21. The method of claim 15, further comprising the step of positioning a projector on the first side of the light-permeable surface such that the projector directs light onto the light-permeable surface to present images visible on the opposite side of the light-permeable surface, with which the physical object can interact.

22. 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.

23. The system of claim 22, 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.

24. The system of claim 22, 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(xy) 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.

25. The system of claim 22, 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.

26. The system of claim 22, 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.

27. 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.

28. The system of claim 27, 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.

29. The system of claim 28, 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(xy) 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) 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.

30. The system of claim 27, 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.

31. The system of claim 27, 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.