Determining proximity of a mobile device to a subject based on shadow analysis

• US 8,983,118 B2
• Filed: 06/18/2013
• Issued: 03/17/2015
• Est. Priority Date: 06/23/2010
• Status: Expired due to Fees

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Conwell, William Y.
• Primary Examiner(s): MARIAM, DANIEL G
• Application Number:
  US13/920,917
• Publication Number:
  US 20140029785A1
• Time in Patent Office: 637 Days
• Field of Search: None
• US Class Current: 382/100
• CPC Class Codes: G06T 1/005 Robust watermarking, e.g. average attack or collusion attack resistant
• CPC Class Codes: G06T 2201/0065 Extraction of an embedded watermark; Reliable detection
• CPC Class Codes: G06T 5/94 based on local image properties, e.g. for local contrast enhancement
• CPC Class Codes: G06T 7/507 from shading G06T7/586 takes precedence

Abstract

The present disclosure relates generally to cell phones and cameras, and to shadow analysis in imagery captured by such cell phones and cameras. One claim recites a method comprising: identifying a shadow cast by a cell phone on a subject being imaged by a camera included in the cell phone; and using a programmed electronic processor, determining proximity to the subject based on an analysis of the shadow. Another claim recites a mobile phone comprising: a camera for capturing images and video; memory; and one or more processors programmed for: identifying a shadow cast by a cell phone on a subject being imaged by said imager; and determining proximity to the subject based on an analysis of the shadow. Of course, other claims and combinations are provided too.

Claims

1. A method comprising:

identifying a shadow cast by a cell phone on a subject being imaged by a camera included in the cell phone; and

using one or more programmed electronic processors, determining proximity to the subject based on an analysis of the shadow.

2. The method of claim 1 in which said determining comprises evaluating a color level of the shadow.

3. The method of claim 1 in which said determining comprises evaluating boundary sharpness associated with the shadow.

4. The method of claim 1 in which said determining comprises evaluating a temporal sequence of image frames to determine color levels of the shadow over the image frames.

5. The method of claim 4 in which a determination is made that the camera is moving closer to the subject as the shadow becomes darker over the temporal sequence of image frames.

6. The method of claim 1 in which said determining comprises evaluating a temporal sequence of image frames to determine boundary sharpness of the shadow over the temporal sequence of image frames.

7. The method of claim 6 in which a determination is made that the camera is moving closer to the subject as the boundary sharpness of the shadow increases over the temporal sequence of image frames.

8. The method of claim 1 further comprising adjusting focus of the camera based on the analysis of the shadow.

9. The method of claim 1 in which the subject comprises a printed or displayed object or graphic.

10. A non-transitory computer readable medium comprising instructions stored therein, said instructions are for causing one or more electronic processors to perform the method of claim 1.

11. A mobile phone comprising:

a camera for capturing images and video;

memory; and

one or more processors programmed for;

identifying a shadow cast by the mobile phone on a subject being imaged by said camera; and

determining proximity to the subject based on an analysis of the shadow.

12. The mobile phone of claim 11 in which the determining comprises evaluating a color level of the shadow.

13. The mobile phone of claim 11 in which the determining comprises evaluating boundary sharpness associated with the shadow.

14. The mobile phone of claim 11 in which the determining comprises evaluating a temporal sequence of image frames to determine color levels of the shadow over the image frames.

15. The mobile phone of claim 14 in which a determination is made that the camera is moving closer to the subject as the shadow becomes darker over the temporal sequence of image frames.

16. The mobile phone of claim 11 in which the determining comprises evaluating a temporal sequence of image frames to determine boundary sharpness of the shadow over the temporal sequence of image frames.

17. The mobile phone of claim 16 in which a determination is made that the camera is moving closer to the subject as the boundary sharpness of the shadow increases over the temporal sequence of image frames.

18. The mobile phone of claim 11 in which said one or more processors are programmed for adjusting focus of said camera based on the analysis of the shadow.

19. The mobile phone of claim 18 further comprising a microphone for capturing audio;

a touchscreen display and a transceiver.

20. The mobile phone of claim 11 in which the subject comprises a printed or displayed object or graphic.

21. A non-transitory computer readable medium comprising instructions stored therein, said instructions are for causing one or more electronic processors to perform the following:

identifying a shadow cast by a cell phone on a subject being imaged by a camera included in the cell phone; and

determining proximity to the subject based on an analysis of the shadow.

22. The non-transitory computer readable medium of claim 21 in which the determining comprises evaluating a color level of the shadow.

23. The non-transitory computer readable medium of claim 21 in which the determining comprises evaluating boundary sharpness associated with the shadow.

24. The non-transitory computer readable medium of claim 21 in which the determining comprises evaluating a temporal sequence of image frames to determine color levels of the shadow over the image frames.

25. The non-transitory computer readable medium of claim 21 in which a determination is made that the camera is moving closer to the subject as the shadow becomes darker over the temporal sequence of image frames.

26. The non-transitory computer readable medium of claim 21 in which the determining comprises evaluating a temporal sequence of image frames to determine boundary sharpness of the shadow over the temporal sequence of image frames.

27. The non-transitory computer readable medium of claim 26 in which a determination is made that the camera is moving closer to the subject as the boundary sharpness of the shadow increases over the temporal sequence of image frames.

28. The non-transitory computer readable medium of claim 21 further comprising instructions for causing one or more electronic processors to perform adjusting focus of the camera based on the analysis of the shadow.

29. The non-transitory computer readable medium of claim 21 in which the subject comprises a printed or displayed object or graphic.