Image stabilization system and method for a video camera

• US 7,742,077 B2
• Filed: 08/09/2005
• Issued: 06/22/2010
• Est. Priority Date: 02/19/2004
• Status: Expired due to Fees

• Current Assignee: Bosch Security Systems Incorporated (Robert Bosch GmbH), Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Bell, Mark, Sablak, Sezai
• Primary Examiner(s): Aggarwal; Yogesh K
• Application Number:
  US11/200,396
• Publication Number:
  US 20050280707A1
• Time in Patent Office: 1,778 Days
• Field of Search: 348/208.99, 348/208.1, 348/208.2, 348/208.4, 348/208.16, 348/208.12, 396/52, 396/53, 396/54, 382/168, 382/172
• US Class Current: 348/208.99
• 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, the analysis of said first and second images including 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 by determining an image difference of said aligned images, said processing device generating a histogram of said image difference of said aligned images and determining whether unintentional camera movement has occurred based upon identifying a maximum peak in said histogram and a location of said maximum peak, and 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.

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 1 wherein the analysis of the first and second images includes finding a pixel-to-pixel correspondence between portions of the first and second images.

7. 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.

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

9. The video image stabilization system of claim 1, wherein the analysis of the first and second images further includes compensating for known movements of the camera between the first and second images based on the signals indicative of the field of view.

10. 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, said determining step including 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 by 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 by determining an image difference of the aligned images and 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, 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.

11. The method of claim 10 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.

12. The method of claim 10 wherein said determining step includes finding a pixel-to-pixel correspondence between portions of the first and second images.

13. The method of claim 10, wherein said determining step includes compensating for known movements of the camera between the first and second images based on signals indicative of the field of view.