HYBRID IMAGE STABILIZATION FOR VIDEO CAMERA

• US 20090309984A1
• Filed: 06/25/2007
• Published: 12/17/2009
• Est. Priority Date: 06/29/2006
• Status: Active Grant

• Current Assignee: Thales SA
• Original Assignee: Thales SA
• Inventors: Bustin, Bruno, Bourgain, Stephane, Rioland, Jacques, Rannou, Christophe, Fournier, Jerome, Payot, Etienne
• Granted Patent: US 8,111,294 B2
• Time in Patent Office: Days
• US Class Current: 348/208.400
• CPC Class Codes: H04N 23/68 for stable pick-up of the scene, e.g. compensating for camera body vibrations
• CPC Class Codes: H04N 23/6812 based on additional sensors, e.g. acceleration sensors
• CPC Class Codes: H04N 23/682 Vibration or motion blur correction

Abstract

The invention relates to a method of stabilizing the images of a scene, acquired by means of an observation device of an imaging system, comprising the step of digital processing of a stream of successive images. It comprises a step of acquiring gyrometric measurements by means of at least one gyrometric sensor secured to the observation device, of using these gyrometric measurements to determine so-called approximate shifts undergone between successive images, and the image processing step comprising a sub-step of using the approximate shifts and the image stream acquired to determine so-called fine shifts undergone between successive images.

Claims

1. A method of stabilizing the images of a scene, acquired by means of an observation device of an imaging system, comprising;

a step of digital processing of a stream of successive images;

a step of acquiring gyrometric measurements by means of at least one gyrometric sensor secured to the observation device, of using these gyrometric measurements to determine approximate shifts undergone between successive images, and in that the image processing step comprises;

i. a sub-step of using the approximate shifts and the image stream acquired to determine so-called fine shifts undergone between successive images and,

ii. a sub-step of evaluating the fine shifts, and

iii. a sub-step of merging the approximate shifts and the fine shifts with a view to applying merged shifts to the image stream so as to stabilize it.

2. The method as claimed in claim 1, wherein the image processing step comprises a sub-step of temporal filtering of the shifts.

3. The method as claimed in claim 1, wherein the step of determining the fine shifts comprises the steps consisting in:

a. dezooming the successive images k times to obtain k reduced-resolution image streams, k being an integer greater than or equal to 1,

b. calculating shifts on the basis of the kth reduced-resolution image stream and the approximate shifts,

c. as long as k is strictly greater than 1, iterating the following process;

i. calculating shifts on the basis of the (k−

1)th reduced-resolution image stream and the preceding shifts,

ii. k=k−

1,

d. calculating the fine shifts on the basis of the preceding shifts and the original image stream.

4. The method as claimed in claim 3, wherein k=1.

5. The method as claimed in claim 1, wherein the shift calculations are obtained by correlation.

6. A device for stabilizing the images of a scene comprising an observation device of an imaging system, an element for digital processing of successive images, comprising:

at least one gyrometric sensor secured to the observation device and linked to the image processing element, and in that the image processing element comprises means for implementing the method as claimed in claim 1.

7. The device as claimed in claim 6, comprising:

a first programmable logic array disposed between the observation device and the gyrometric sensor or sensors on the one hand and the image processing element on the other hand, this programmable logic array being able to acquire gyrometric measurements from the sensors and an image stream from the observation device.

8. The device as claimed in claim 7, comprising:

another programmable logic array positioned disposed at the output of the image processing element and linked to the observation device and able to apply the shifts provided by the image processing element to the image stream arising from the first programmable logic array.

9. The device as claimed in claim 6, comprising:

a programmable logic array linked to the observation device and to the image processing element and able to acquire gyrometric measurements from the sensors and an image stream from the observation device and to apply the shifts provided by the image processing element to said image stream.

10. The device as claimed in claim 7, wherein the programmable logic array is an FPGA.

11. The method as claimed in claim 2, wherein the step of determining the fine shifts comprises the steps consisting in:

a. dezooming the successive images k times to obtain k reduced-resolution image streams, k being an integer greater than or equal to 1,

b. calculating shifts on the basis of the (k−

1)th reduced-resolution image stream and the approximate shifts,

c. as long as k is strictly greater than 1, iterating the following process;

i. calculating shifts on the basis of the (k−

1)th reduced-resolution image stream and the preceding shifts,

ii. k=k−

1,

d. calculating the fine shifts on the basis of the preceding shifts and the original image stream.

12. The method as claimed in claim 2, wherein the shift calculations are obtained by correlation.

13. The method as claimed in claim 3, wherein the shift calculations are obtained by correlation.

14. The method as claimed in claim 4, wherein the shift calculations are obtained by correlation.

15. The device as claimed in claim 8, wherein the programmable logic array is an FPGA.

16. The device as claimed in claim 9, wherein the programmable logic array is an FPGA.