Method and apparatus for inhibiting projection of selected areas of a projected image

• US 6,361,173 B1
• Filed: 02/16/2001
• Issued: 03/26/2002
• Est. Priority Date: 02/16/2001
• Status: Expired due to Term

• Current Assignee: iMatte, Inc.
• Original Assignee: iMatte, Inc.
• Inventors: Vlahos, Petro, Dadourian, Arpag, Vlahos, Paul
• Primary Examiner(s): DOWLING, WILLIAM C
• Application Number:
  US09/788,026
• Time in Patent Office: 403 Days
• Field of Search: 353/122, 353/28, 353/97, 348/586, 348/590, 348/607
• US Class Current: 353/97
• CPC Class Codes: G03B 21/14 Details
• CPC Class Codes: G03B 21/26 Projecting separately subsidiary matter simultaneously with main image
• CPC Class Codes: H04N 5/74 Projection arrangements for image reproduction, e.g. using eidophor
• CPC Class Codes: H04N 9/3194 including sensor feedback

Abstract

A video projector shows the desired scene on a projection screen. An infrared source close to the video projector uniformly floods the projection screen with non-visible infrared radiation. An infrared sensitive camera, also close to the video projector, observes the projection screen and sees only the uniform infrared illumination of the screen. Upon entry of a subject into the projected video image, the infrared reflected from the subject will not match that of the projection screen and thus the subject area is identified. All pixels of the projected scene, in the area occupied by the subject, are inhibited before reaching the video projector. The subject may then look directly at an audience without being blinded by the projector.

Claims

1. A method for inhibiting projection of a portion of an image being projected onto a projection screen when a subject enters a beam used to produce the projected image comprising the steps of:

a) identifying a portion of the projected image that would be intercepted by the subject entering said beam by a predetermined detection technique;

b) inhibiting the signal level of pixels in said portion, to reduce signal levels of the beam projected onto said subject.

3. The method of claim 1 in which said projection screen is one of a white wall, a matte white projection screen, a beaded screen, a metallic coated lenticular screen.

6. The method of claim 1 in which said inhibit signal varies as one of a linear and nonlinear function of infrared deviation between said subject and said reference frame.

7. The method of claim 1 in which those pixels whose signal levels have been inhibited are provided by signal levels created by said inhibiting to provide one of colored and white light illumination of the subject.

8. The method of claim 7 in which said one of colored and white light illumination is inhibited from illuminating a face of the subject by determining a location of the subject'"'"'s head.

2. A method for inhibiting projection of a portion of an image being projected onto a projection screen when a subject enters into a beam used to produce the projected image comprising the steps of:

a) uniformly illuminating said projection screen with infrared radiation from an infrared source,

b) projecting a visible image onto said projection screen,

c) capturing pixel signal levels produced by said infrared illuminated projection screen using an infrared sensitive camera,

d) storing the captured signal levels as an infrared reference frame,

e) comparing said signal levels in said reference frame with infrared sensitive signal levels of each image frame being projected and captured,

f) identifying a pixel in said subject area as a pixel in the infrared sensitive camera image whose infrared signal level does not match said stored infrared signal level at a corresponding address in said infrared reference frame,

g) inhibiting the signal levels of each pixel in the projected image whose address has been identified as being a subject address, thereby preventing the beam containing the projected image from being projected onto said subject.

4. The method of claim 2 in which at least two infrared bands are employed, and said subject is detected if a mismatch occurs at a given pixel location between the new image frame signal levels and the stored reference frame signal levels, for any one of the at least two infrared bands.

5. The method of claim 2 in which the stored reference frame signal levels are updated at predetermined intervals to maintain a match between the infrared signals in the stored reference frame and the signal levels from the camera in areas of the screen without said subject to eliminate effects of line voltage variations.

9. The method of claims 2 in which said projection screen is one of a white wall, a matte white projection screen, a beaded screen, a metallic coated lenticular screen.

10. The method of claim 2 in which said inhibit signal varies as one of a linear and nonlinear function of infrared deviation between said subject and said reference frame.

11. The method of claim 2 in which those pixels whose signal levels have been inhibited are provided by signal levels created by said inhibiting to provide one of colored and white light illumination of the subject.

12. The method of claim 11 in which said one of colored and white light illumination is inhibited from illuminating a face of the subject by determining a location of the subject'"'"'s head.

13. An apparatus for inhibiting projection of a portion of an image being projected onto a projection screen when a subject enters a beam used to produce the projected image comprising:

a) means for identifying a portion of the projected image that would be intercepted by the subject entering said beam by a predetermined detection technique;

b) means for inhibiting the signal level of pixels in said portion, to reduce signal levels of the beam projected onto said subject.

15. The apparatus of claims 13 in which said projection screen is one of a white wall, a matte white projection screen, a beaded screen, a metallic coated lenticular screen.

18. The apparatus of claim 13 in which said inhibit signal varies as one of a linear and nonlinear function of infrared deviation between said subject and said reference frame.

19. The apparatus of claim 13 in which those pixels whose signal levels have been inhibited are provided by signal levels created by said inhibiting means to provide one of colored and white light illumination of the subject.

20. The apparatus of claim 19 in which said one of colored and white light illumination is inhibited from illuminating a face of the subject by determining a location of the subject'"'"'s head.

14. An apparatus for inhibiting projection of a portion of an image being projected onto a projection screen when a subject enters into a beam used to produce the projected image comprising:

a) means for uniformly illuminating said projection screen with infrared radiation from an infrared source,

b) means for projecting a visible image onto said projection screen,

c) means for capturing pixel signal levels produced by said infrared illuminated projection screen using an infrared sensitive camera,

d) means for storing the captured signal levels as an infrared reference frame,

e) means for comparing said signal levels in said reference frame with infrared sensitive signal levels of each image frame being projected and captured,

f) means for identifying a pixel in said subject area as a pixel in the infrared sensitive camera image whose infrared signal level does not match said stored infrared signal level at a corresponding address in said infrared reference frame,

g) means for inhibiting the signal levels of each pixel in the projected image whose address has been identified as being a subject address, thereby preventing the beam containing the projected image from being projected onto said subject.

16. The apparatus of claim 14 in which at least two infrared bands are employed, and said subject is detected if a mismatch occurs at a given pixel location between the new image frame signal levels and the stored reference frame signal levels, for any one of the at least two infrared bands.

17. The apparatus of claim 14 in which the stored reference frame signal levels are updated at predetermined intervals to maintain a match between the infrared signals in the stored reference frame and the signal levels from the camera in areas of the screen without said subject to eliminate effects of line voltage variations.

21. The apparatus of claims 14 in which said projection screen is one of a white wall, a matte white projection screen, a beaded screen, a metallic coated lenticular screen.

22. The apparatus of claim 14 in which said inhibit signal varies as one of a linear and nonlinear function of infrared deviation between said subject and said reference frame.

23. The apparatus of claim 14 in which those pixels whose signal levels have been inhibited are provided by signal levels created by said inhibiting to provide one of colored and white light illumination of the subject.

24. The apparatus of claim 23 in which said one of colored and white light illumination is inhibited from illuminating a face of the subject by determining a location of the subject'"'"'s head.