Method And Apparatus For Inhibiting A Subject's Eyes From Being Exposed To Projected Light

• US 20070273842A1
• Filed: 05/24/2006
• Published: 11/29/2007
• Est. Priority Date: 05/24/2006
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Smart Technologies ULC (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Holmgren, David E., Chtchetinine, Alex, Morrison, Gerald, Wang, Yunqiu (Rachel), Forrest, Gregory G., Howse, Brian
• Granted Patent: US 7,984,995 B2
• Time in Patent Office: Days
• US Class Current: 353/97
• CPC Class Codes: G03B 17/54 with projector
• CPC Class Codes: G03B 21/14 Details
• CPC Class Codes: G03B 21/2053 Intensity control of illuminating light controlled by video signal processing H04N5/74 or H04N9/31
• CPC Class Codes: H04N 5/74 Projection arrangements for image reproduction, e.g. using eidophor
• CPC Class Codes: H04N 9/3179 Video signal processing therefor
• CPC Class Codes: H04N 9/3194 including sensor feedback

Abstract

A method of inhibiting a subject'"'"'s eyes from being exposed to projected light when the subject is positioned in front of a background on which an image is displayed comprises capturing at least one image of the background including the displayed image, processing the captured image to detect the existence of the subject and to locate generally the subject and masking image data used by the projector to project the image corresponding to a region that encompasses at least the subject'"'"'s eyes.

Claims

1. In a projection system where a projector is used to project an image for display on a background, a method of inhibiting a subject'"'"'s eyes from being exposed to projected light when the subject is positioned in front of the background, said method comprising:

capturing at least one image of the background including the displayed image;

processing the captured at least one image to detect the existence of a subject and to locate generally the subject; and

masking image data used by the projector to project the image, corresponding to a region that encompasses at least the subject'"'"'s eyes.

2. The method of claim 1 wherein during said masking, pixels in said region are set to a black or near black level.

3. The method of claim 1 wherein said region is geometrically shaped and generally encompasses the subject'"'"'s head.

4. The method of claim 3 wherein during said capturing, multiple images are captured and wherein during said processing, a disparity image based on the captured images is generated.

5. The method of claim 4 wherein during said capturing, sets of images are successively captured and mapped to one another, each set of mapped images being processed to yield the disparity image.

6. The method of claim 5 wherein during said processing, said disparity image is processed to detect generally the center of the subject'"'"'s head, said geometrically shaped region being generally centered about the center of the subject'"'"'s head.

7. The method of claim 6 wherein during processing, said disparity image is examined to determine if a subject exists therein, if so, said disparity image is thresholded prior to processing to detect generally the center of the subject'"'"'s head.

8. The method of claim 7 further comprising tracking the subject'"'"'s head over successive sets of images and calculating an average center position, said average center position being used to position said geometrically shaped region.

9. The method of claim 8 further comprising calculating an average head velocity and using said average level velocity and average head position to position said geometrically shaped region.

10. The method of claim 6 wherein said disparity image is a statistical cross-correlation of each set of mapped images.

11. The method of claim 6 wherein said disparity image is a weighted differential of each set of mapped images.

12. The method of claim 6 wherein said disparity image is an absolute differential of each set of mapped images.

13. The method of claim 5 wherein the images of each set are mapped to one another via a transformation determined during calibration.

14. The method of claim 13 wherein said transformation is a homography transformation based on common features in captured images.

15. The method of claim 14 wherein said common features comprise features of a calibration image projected on said background.

16. The method of claim 15 wherein said calibration image is a graphical user interface.

17. The method of claim 16 wherein said common features are corners and wherein said common features further comprise corners of said background.

18. The method of claim 17 wherein said background is an electronic whiteboard.

19. The method of claim 7 wherein during thresholding, clusters of pixels representing said subject are isolated, said pixels clusters being examined to detect generally the center of the subject'"'"'s head.

20. The method of claim 19 wherein during processing to detect the center of the subject'"'"'s head, the center of said pixel clusters, the centerline of the subject and the outline of said subject are determined and examined to locate the position of the subject'"'"'s head, said head position being used to determine the center of the subject'"'"'s head.

21. The method of claim 4 wherein during said capturing, sets of images are successively captured and mapped to one another, each set of images being processed to detect the subject'"'"'s shadow, said detected shadow being used to locate the subject'"'"'s head.

22. The method of claim 3 wherein said processing further comprises:

examining the captured at least one image to detect interruption of a datum line therein thereby to detect the existence of the subject.

23. The method of claim 22 wherein said datum line is generally horizontal and is located adjacent the bottom of the displayed image.

24. The method of claim 23 wherein the datum line is the lower boundary of the displayed image.

25. The method of claim 23 wherein the datum line is a bright band in the displayed image.

26. The method of claim 23 wherein the datum light results from a band of light reflected by said background.

27. In a projection system where a projector is used to project an image for display on a background, a method of inhibiting a subject'"'"'s eyes from being exposed to projected light when the subject is positioned in front of the background, said method comprising:

successively capturing sets of images of the background including the displayed image;

processing each set of captured images to detect the existence of the subject and to locate generally the subject'"'"'s head; and

modifying image data used by the projector to project the image, in a region encompassing the subject'"'"'s head such that the displayed image comprises an area of darkness encompassing the subject'"'"'s head.

28. The method of claim 27 wherein the images of each set are mapped to one another, the mapped images being processed to yield a disparity image.

29. The method of claim 28 wherein during processing, said disparity image is examined to determine if a subject exists therein, if so, said disparity image is thresholded prior to processing to detect generally the center of the subject'"'"'s head.

30. The method of claim 29 further comprising tracking the subject'"'"'s head over successive sets of images and calculating an average center position, said average center position being used to position said geometrically shaped region.

31. The method of claim 30 wherein the images of each set are mapped to one another via a transformation determined during calibration.

32. The method of claim 31 wherein said transformation is a homography transformation based on common features in captured images.

33. The method of claim 32 wherein said common features comprise features of a calibration image projected on said background.

34. The method of claim 33 wherein said calibration image is a graphical user interface.

35. The method of claim 34 wherein said common features are corners and wherein said common features further comprise corners of said background.

36. The method of claim 29 wherein during thresholding, clusters of pixels representing said subject are isolated, said pixels clusters being examined to detect generally the center of the subject'"'"'s head.

37. The method of claim 36 wherein during processing to detect the center of the subject'"'"'s head, the center of said pixel clusters, the centerline of the subject and the outline of said subject are determined and examined to locate the position of the subject'"'"'s head, said head position being used to determine the center of the subject'"'"'s head.

38. A projection system comprising:

a projector receiving image data and projecting an image onto a background;

at least one camera capturing images of the background including the projected image; and

processing structure processing the captured images to detect the existence of a subject and to locate generally the subject and masking image data used by the projector to project the image, corresponding to a region that encompasses at least the subject'"'"'s eyes.

39. A projection system according to claim 38 further comprising a video source providing the image data to said projector.

40. A projection system according to claim 39 wherein said video source is a computer.

41. A projection system according to claim 40 wherein said computer is coupled to said at least one camera and masks the image data.

42. A projection system according to claim 41 wherein said computer processes the captured images to detect when the subject occludes projected light and to locate generally the subject'"'"'s head.

43. A projection system according to claim 42 wherein during masking, said processing structure sets pixels in the region to a black or near black level.

44. A projection system according to claim 43 wherein said region is geometrically shaped and generally encompasses the subject'"'"'s head.

45. A projection system according to claim 44 further comprising multiple cameras successively capturing image sets of the background including the projected image, said projection system mapping the images of each set to one another and processing the mapped images to yield a disparity image, said disparity being examined to detect the existence of the subject and to locate the subject'"'"'s head.

46. A projection system comprising:

a projector receiving image data and projecting an image onto a background;

a scanner scanning the background to detect the existence of a subject in front of the background; and

processing structure communicating with the scanner said processing structure being responsive to said scanner and masking the image data used by the projector to project the image corresponding to a region that encompasses at least the subject'"'"'s eyes thereby to inhibit projected light from being directed at the subject'"'"'s eyes.

47. A projection system according to claim 46 wherein said scanner is a range finder.

48. A projection system according to claim 46 wherein said scanner is a light sensing device.