Method and apparatus for masking surveillance video images for privacy protection

• US 20070115356A1
• Filed: 11/07/2006
• Published: 05/24/2007
• Est. Priority Date: 11/07/2005
• Status: Active Grant

• Current Assignee: LG Innotek Company Limited (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Park, Byung, Seo, Sung, Choi, Jong, Kang, Kyun
• Granted Patent: US 8,194,127 B2
• Time in Patent Office: Days
• US Class Current: 348/143
• CPC Class Codes: G06T 7/32 using correlation-based methods
• CPC Class Codes: G08B 13/19636 pertaining to the camera
• CPC Class Codes: G08B 13/19686 Interfaces masking personal details for privacy, e.g. blurring faces, vehicle license plates

Abstract

The present invention makes a privacy protection area set on a video frame always match a masking block for the privacy protection area, thereby preventing video images taken from the privacy protection area from being exposed. One embodiment of the invention sets a masking zone corresponding to a privacy protection area on a taken video frame, keeps examining if the set masking zone does not match the privacy protection area, and adjusts the position of the masking zone on the video frame if it is determined that the masking zone does not match the privacy protection area, thereby preventing video signals taken from the initially set privacy protection area from being outputted.

Claims

1. A method for masking a surveillance image taken with a camera, comprising:

(a) setting a masking zone corresponding to a protection area on a video frame being taken with the camera;

(b) determining whether the masking zone is deviated from the protection area; and

(c) adjusting a position of the masking zone on the video frame if it is determined that the masking zone is deviated.

2. The method of claim 1, wherein a shape of the masking zone is rectangular.

3. The method of claim 1, wherein the step (b) periodically obtains video data contained in the set masking zone from the video frame being taken with the camera, calculates a correlation between the obtained video data and video data obtained from the masking zone when the masking zone is set at the step (a), and determines whether the masking zone is deviated from the protection area based on the calculated correlation.

4. The method of claim 1, wherein the step (b) periodically obtains video data contained in a predetermined reference zone from the video frame being taken with the camera, calculates a correlation between the obtained video data and video data obtained from the predetermined reference zone when the masking zone is set at the step (a), and determines whether the masking zone is deviated from the protection area based on the calculated correlation.

5. The method of claim 3, wherein the correlation is a value determined based on:

a sum of products of corresponding pixel values of two video data groups obtained from the zone at different times,

an average of pixel values of the two video data groups, or

a standard deviation of pixel values of the two video data groups.

6. The method of claim 4, wherein the correlation is a value determined based on:

a sum of products of corresponding pixel values of two video data groups obtained from the zone at different times,

an average of pixel values of the two video data groups, or

a standard deviation of pixel values of the two video data groups.

7. The method of claim 3, wherein the step (b) determines that the masking zone is deviated from the protection area if the calculated correlation is less than a threshold value.

8. The method of claim 4, wherein the step (b) determines that the masking zone is deviated from the protection area if the calculated correlation is less than a threshold value.

9. The method of claim 3, wherein the step (b) uses partial components of the video data obtained from the masking zone to calculate the correlation.

10. The method of claim 4, wherein the step (b) uses partial components of the video data obtained from the masking zone to calculate the correlation.

11. The method of claim 1, wherein if the step (b) determines that the masking zone is deviated from the protection area, the step (c) searches the current video frame for a zone containing video data which has a highest correlation with the video data which was obtained and stored when the masking zone was set at the step (a), and sets a position of the found zone as the position of the masking zone.

12. The method of claim 1, further comprising:

(d) re-adjusting the position of the masking zone on the video frame based on an amount of a horizontal and/or vertical movement of a view angle of the camera or based on a picture-taking magnification of the camera.

13. The method of claim 1, further comprising:

(d) outputting the video frame being taken with the camera after blocking a video signal corresponding to the set masking zone.

14. The method of claim 1, wherein the steps (b) and (c) are conducted periodically during a predetermined time zone or are conducted at a predetermined time.

15. An apparatus for masking a surveillance image taken with a camera, comprising:

an opto-electric processing unit to convert an input optical ray into electrical video frames;

a controller to set a masking zone corresponding to a protection area on a video frame, to determine whether the masking zone is deviated from the protection area, and to adjust a position of the masking zone on the video frame if it is determined that the masking zone is deviated from the protection area; and

masking means for blocking the video signal corresponding to the set masking zone on the video frame.

16. The apparatus of claim 15, wherein a shape of the masking zone is rectangular.

17. The apparatus of claim 15, wherein the controller periodically obtains video data contained in the set masking zone from the video frame, calculates a correlation between the obtained video data and video data obtained from the masking zone when the masking zone is set, and determines whether the masking zone is deviated from the protection area based on the calculated correlation.

18. The apparatus of claim 15, wherein the controller periodically obtains video data contained in a predetermined reference zone from the video frame, calculates a correlation between the obtained video data and video data obtained from the predetermined reference zone when the masking zone is set, and determines whether the masking zone is deviated from the protection area based on the calculated correlation.

19. The apparatus of claim 18, wherein a shape of the reference zone is rectangular.

20. The apparatus of claim 17, wherein the correlation is a value determined based on:

a sum of products of corresponding pixel values of two video data groups obtained from the zone at different times,

an average of pixel values of the two video data groups, or

a standard deviation of pixel values of the two video data groups.

21. The apparatus of claim 18, wherein the correlation is a value determined based on:

a sum of products of corresponding pixel values of two video data groups obtained from the zone at different times,

an average of pixel values of the two video data groups, or

a standard deviation of pixel values of the two video data groups.

22. The apparatus of claim 17, wherein the controller determines that the masking zone is deviated from the protection area if the calculated correlation is less than a threshold value.

23. The apparatus of claim 18, wherein the controller determines that the masking zone is deviated from the protection area if the calculated correlation is less than a threshold value.

24. The apparatus of claim 17, wherein the controller uses partial components of the video data obtained from the masking zone to calculate the correlation.

25. The apparatus of claim 18, wherein the controller uses partial components of the video data obtained from the masking zone to calculate the correlation.

26. The apparatus of claim 15, wherein if the controller determines that the masking zone is deviated from the protection area, the controller searches the current video frame for a zone containing video data which has a highest correlation with the video data which was obtained and stored when the masking zone was set, and sets a position of the found zone as the position of the masking zone.

27. The apparatus of claim 15, further comprising:

a panning/tilting unit to adjust an optical axis of the opto-electric processing unit horizontally and/or vertically, wherein the controller further re-adjusts the position of the masking zone on the video frame based on an amount of the horizontal and/or vertical adjustment by the panning/tilting unit.

28. The apparatus of claim 15, wherein the controller further re-adjusts the position of the masking zone on the video frame based on a picture-taking magnification of the opto-electric processing unit.