Image stabilization system and method for a video camera

• US 20050280707A1
• Filed: 08/09/2005
• Published: 12/22/2005
• Est. Priority Date: 02/19/2004
• Status: Active Grant

• Current Assignee: Bosch Security Systems Incorporated (Robert Bosch GmbH), Robert Bosch GmbH
• Original Assignee: Bosch Security Systems Incorporated (Robert Bosch GmbH), Robert Bosch GmbH
• Inventors: Bell, Mark, Sablak, Sezai
• Granted Patent: US 7,742,077 B2
• Time in Patent Office: Days
• US Class Current: 348/155
• CPC Class Codes: H04N 23/68 for stable pick-up of the scene, e.g. compensating for camera body vibrations
• CPC Class Codes: H04N 23/6811 based on the image signal
• CPC Class Codes: H04N 23/6815 by distinguishing pan or tilt from motion
• CPC Class Codes: H04N 23/682 Vibration or motion blur correction
• CPC Class Codes: H04N 23/6845 by combination of a plurality of images sequentially taken

Abstract

A video image stabilization system includes a camera having an image capturing device capturing a video image. The camera has a selectively adjustable field of view. A processing device is operably coupled to the camera. The processing device receives signals indicative of the field of view of the camera and images captured by the camera. The processing device automatically tracks movements of at least one object in the images. The processing device determines a stabilizing adjustment for the video image as a function of an unintended change in the field of view of the camera during a time interval between capture of a first image and capture of a second image. The determining is based upon the signals indicative of the field of view and an analysis of the first and second images.

Claims

1. A video image stabilization system comprising:

a camera including an image capturing device configured to capture a video image, said camera having a selectively adjustable field of view; and

a processing device operably coupled to said camera wherein said processing device receives signals indicative of the field of view of said camera and images captured by said camera, said processing device automatically tracking movements of at least one object in the images, said processing device determining a stabilizing adjustment for the video image as a function of an unintended change in the field of view of said camera during a time interval between capture of a first image and capture of a second image, the determining being based upon said signals indicative of the field of view and an analysis of said first and second images.

2. The video image stabilization system of claim 1 wherein a display portion of each image captured by said camera is selected for display, said selected display portion of each image comprising less than the entire captured image and wherein said stabilizing adjustment determined by said processing device comprises adjusting a relative location of said selected display portion within said captured image.

3. The video image stabilization system of claim 1 wherein said camera has a selectively adjustable pan position, a selectively adjustable tilt position and a selectively adjustable focal length.

4. The video image stabilization system of claim 3 wherein at least one of the pan position, the tilt position, and the focal length of said camera is intentionally adjusted between the capture of said first and second images.

5. The video image stabilization system of claim 1 wherein the analysis of the first and second images includes determining the unintended change in the field of view of said camera during the interval between the capture of the first image and the second image.

6. The video image stabilization system of claim 5 wherein the analysis of the first and second images includes finding a pixel-to-pixel correspondence between the first and second images.

7. The video image stabilization system of claim 1 wherein said analysis of said first and second images includes aligning one of said first and second images with an other of said first and second images based upon said signals indicative of the field of view and determining if said aligned images indicate an occurrence of unintentional camera movement.

8. The video image stabilization system of claim 7 wherein determining if said aligned images indicate the occurrence of unintentional camera movement comprises determining an image difference of said aligned images.

9. The video image stabilization system of claim 8 wherein said processing device generates a histogram of said image difference of said aligned images and determines whether unintentional camera movement has occurred based upon identifying a maximum peak in said histogram and a location of said maximum peak.

10. The video image stabilization system of claim 9 wherein when said maximum peak is not substantially centered on zero, unintentional camera movement is determined to have occurred and wherein determination of said stabilizing adjustment includes identifying adjustments that reduce the image difference.

11. The video image stabilization system of claim 1 wherein said signals indicative of the field of view comprise pan, tilt and focal length settings of said camera for each captured image, said signals being communicated to said processing device from said camera on an image-synchronized basis.

12. The video image stabilization system of claim 1 wherein said camera is moveably mounted on a stationary support.

13. A video image stabilization system comprising:

a video camera including an image-capturing device configured to capture images, each captured image associated with a field of view, said camera having at least one selectively adjustable parameter wherein adjustment of said at least one camera parameter varies the field of view of said camera;

a display device configured to display a selected portion of the images captured by said camera; and

a processing device operably coupled to said camera and to said display device wherein said processing device receives images captured by said camera, said processing device being operable to track movements of an object in the images and compensate for inadvertent movement of said video camera by adjusting the selected portion of the images displayed by said display device, the adjusting being based upon the camera parameter and an analysis of the images.

14. The video image stabilization system of claim 13 wherein the at least one camera parameter comprises at least one of pan, tilt and zoom settings.

15. The video image stabilization system of claim 13 wherein the selected portion of the images comprises a central portion of the images.

16. The video image stabilization system of claim 13 wherein the selected portion of the images includes approximately between 60% and 90% of the images.

17. A method of stabilizing video images, said method comprising:

capturing a plurality of images with a video camera;

identifying a location of an object in each of a first captured image and a second captured image;

adjusting a field of view of the camera during a time interval between the capture of the first image and the capture of the second image;

displaying a selected display portion of the first captured image and the second captured image, the selected display portion of each image being less than the entire captured image, at least one of the adjusting and displaying steps being dependent upon said identifying step; and

determining a stabilizing adjustment for the second captured image dependent upon said adjusting step and an analysis of the first and second captured images wherein the stabilizing adjustment includes adjusting a relative location of the selected display portion within the second captured image.

18. The method of claim 17 wherein the camera defines a pan position and a tilt position, said adjusting step including adjusting at least one of the pan position, the tilt position, and a focal length of the camera during the time interval between the capture of the first and second images.

19. The method of claim 17 wherein said determining step includes ascertaining an unintended change in the field of view of said camera during the time interval between the capture of the first image and the second image.

20. The method of claim 19 wherein said determining step includes finding a pixel-to-pixel correspondence between the first and second images.

21. The method of claim 19 wherein said ascertaining substep includes:

aligning one of the first and second images with an other of the first and second images based upon signals indicative of the field of view; and

detecting whether the aligned images indicate an occurrence of unintentional camera movement.

22. The method of claim 21 wherein said detecting whether the aligned images indicate the occurrence of unintentional camera movement comprises determining an image difference of the aligned images.

23. The method of claim 22 further comprising generating a histogram of the image difference of the aligned images and determining whether unintentional camera movement has occurred based upon identifying a maximum peak in the histogram and a location of the maximum peak.

24. The method of claim 23 wherein when the maximum peak is not substantially centered on zero, unintentional motion is determined to have occurred and wherein determination of said stabilizing adjustment includes identifying adjustments that reduce the image difference.

25. A method of stabilizing video images, said method comprising:

capturing a plurality of images with a video camera;

tracking movement of an object in the images;

varying a field of view of said camera by use of control signals;

displaying a selected portion of each of the plurality of images, at least one of said varying step and said displaying step being dependent upon said tracking step; and

adjusting the selected portion that is displayed for at least one of the plurality of images, said adjusting step compensating for inadvertent movement of the video camera and being based upon an intended field of view of the camera and an analysis of the images.