Method and system for image stabilization

Patent metadata

Field	Value
Publication number	US-2016295115-A1
Application number	US-201615049952-A
Country	US
Kind code	A1
Filing date	Feb 22, 2016
Priority date	Apr 2, 2015
Publication date	Oct 6, 2016
Grant date	—

Abstract

In a method for image stabilization a number of operations are performed to stabilize an image and to output a focal length value. The steps include capturing video by means of a video camera with unknown focal length running an image stabilization process operating on an input from a hardware detector detecting the displacement of the camera and on an adjustable focal length value. Inter-image displacement is corrected based on the input from the hardware detector and the adjustable focal length value. By evaluating the displacement and adjusting the focal length value until a satisfactory image stabilization is achieved a value of the focal length may be output.

First claim

What is claimed is:

1 . A method for image stabilization, the method comprising:
capturing video by means of a video camera having a lens with an unknown focal-length setting and running an image stabilization process, wherein the image stabilization process operates on an input from a hardware detector, detecting the displacement of the camera, and on an adjustable focal length value, correcting displacement within captured video based on the input from the hardware detector and the adjustable focal length value, evaluating displacement in the captured video of stationary objects of a scene at the present operation of the image stabilization process at the presently set focal length value, and adjusting the adjustable focal length value until the evaluated displacement is below a threshold value or at a minimum.

2 . The method of claim 1 , wherein the adjustable focal length value is adjusted based on a user input.

3 . The method of claim 1 , wherein the threshold value is pre-set.

4 . The method of claim 1 , wherein the threshold value is set by an operator.

5 . The method of claim 1 , wherein the adjustable focal length value is adjusted according to an iterative optimization process until the displacement is below the predetermined threshold value.

6 . The method of claim 1 , further comprising outputting a quantification of the adjustable focal-length value.

7 . The method of claim 1 , wherein evaluation is performed on consecutive images in an image stream until the evaluated displacement is below the threshold value.

8 . The method of claim 1 , wherein the hardware detector detects an angular shift.

9 . The method of claim 1 , wherein the hardware detector is an inclinometer, such as a gyroscopic device or a tiltmeter/tiltsensor or an accelerometer.

10 . The method of claim 1 , wherein the hardware detector detects a displacement of the video camera continuously, and wherein a time stamp of the displacement may be correlated with data of an individual frame.

11 . Use of the method according to claim 1 in a process of quantifying the focal length for a video camera system, the process comprising directly or indirectly inducing a shake or vibration to the video camera prior to or during applying the method.

12 . A system for image stabilization of output images from a video camera using as input:
an output of a hardware detector detecting a displacement of the video camera, and an adjustable value representing an estimated focal length setting, wherein the system comprises a processing unit configured to: perform correction of a shift in an image based on the output from the hardware detector and the adjustable value, and to compare consecutive shift-corrected images, and to adjust the adjustable value until a shift between consecutive shift corrected images is below a threshold or at a minimum.

Assignees

• Axis Ab

Inventors

• Hjelmström Jonas
• Nilsson Andreas

Classifications

• H04N23/683 Primary

  performed by a processor, e.g. controlling the readout of an image memory · CPC title

• H04N23/695

  Control of camera direction for changing a field of view, e.g. pan, tilt or based on tracking of objects · CPC title

• H04N23/687 Primary

  by shifting the lens or sensor position · CPC title

• H04N23/80

  Camera processing pipelines; Components thereof · CPC title

• H04N23/6812 Primary

  based on additional sensors, e.g. acceleration sensors · CPC title