Non-uniformity correction techniques for infrared imaging devices

• US 9,723,227 B2
• Filed: 12/06/2013
• Issued: 08/01/2017
• Est. Priority Date: 06/10/2011
• Status: Active Grant

• Current Assignee: Teledyne FLIR LLC (Teledyne Technologies Incorporated)
• Original Assignee: FLIR Systems, Inc. (Teledyne Technologies Incorporated)
• Inventors: Strandemar, Katrin, Hoelter, Theodore R., Hgasten, Nicholas
• Primary Examiner(s): Rao, Andy
• Assistant Examiner(s): Edwards, Tyler
• Application Number:
  US14/099,818
• Publication Number:
  US 20140092257A1
• Time in Patent Office: 1,334 Days
• CPC Class Codes: H04N 5/33 Transforming infrared radiation cameras or camera modules for generating image signals from infrared radiation H04N23/20; circuitry of SSIS for transforming infrared radiation into image signals H04N25/20

Abstract

Various techniques are disclosed for performing non-uniformity correction (NUC) for infrared imaging devices. Intentionally blurred image frames may be obtained and processed to correct for FPN (e.g., random spatially uncorrelated FPN in one embodiment) associated with infrared sensors of the infrared imaging device. Intentionally blurred image frames may be used to distinguish between FPN associated with the infrared sensors and desired scene information. Advantageously, such techniques may be implemented without requiring the use of a shutter to perform flat field correction for the infrared imaging device.

Claims

1. A method of removing noise from image frames captured by an infrared imaging device, the method comprising:

receiving an intentionally blurred image frame, wherein the blurred image frame comprises blurred thermal image data associated with a scene and noise introduced by the infrared imaging device;

determining, for each row of the blurred image frame, a corresponding row fixed pattern noise (FPN) correction term;

determining, for each column of the blurred image frame, a corresponding column FPN correction term;

applying the row and column FPN correction terms to the blurred image frame to provide a corrected blurred image frame;

processing the corrected blurred image frame to determine a plurality of non-uniformity correction (NUC) terms to reduce a portion of the noise comprising spatially uncorrelated fixed pattern noise (FPN); and

applying the NUC terms to the captured image frames.

2. The method of claim 1, further comprising accumulating a set of the image frames captured while the infrared imaging device is in motion relative to at least a portion of the scene to provide the intentionally blurred image frame.

3. The method of claim 2, wherein the motion is a movement of the infrared imaging device initiated by a user to perform a NUC correction.

4. The method of claim 2, further comprising:

detecting the motion; and

selecting the set of image frames based on the detected motion.

5. The method of claim 4, wherein the detecting the motion comprises evaluating pixels of the image frames.

6. The method of claim 4, wherein the detecting the motion comprises monitoring a motion sensor.

7. The method of claim 2, further comprising temporally filtering the captured image frames before the accumulating.

8. The method of claim 7, wherein the temporal filtering comprises:

comparing a first image frame with a second image frame; and

detecting motion based on an average change exhibited by neighborhoods of corresponding pixels in the first and second image frames.

9. The method of claim 1, further comprising:

intentionally defocusing the infrared imaging device; and

capturing the blurred image frame from the scene while the infrared imaging device is defocused.

10. The method of claim 1, wherein the scene is an environment in which the infrared imaging device is located.

11. The method of claim 1, wherein the infrared imaging device is adapted to be implemented in a mobile device.

12. The method of claim 1, wherein the receiving, processing, and applying are performed by a remote system in communication with the infrared imaging device.

13. A device comprising:

an infrared imaging device comprising a plurality of infrared sensors adapted to capture image frames; and

a processor adapted to process an intentionally blurred image frame, wherein the blurred image frame comprises blurred thermal image data associated with a scene and noise introduced by the infrared imaging device, wherein the processor is adapted to;

determine, for each row of the blurred image frame, a corresponding row fixed pattern noise (FPN) correction term;

determine, for each column of the blurred image frame, a corresponding column FPN correction term;

apply the row and column FPN correction terms to the blurred image frame to provide a corrected blurred image frame;

use the corrected blurred image frame to determine a plurality of non-uniformity correction (NUC) terms to reduce a portion of the noise comprising spatially uncorrelated fixed pattern noise (FPN), and

apply the NUC terms to the captured image frames.

14. The device of claim 13, wherein the processor is adapted to accumulate a set of the image frames captured while the infrared imaging device is in motion relative to at least a portion of the scene to provide the blurred image frame.

15. The device of claim 14, wherein the motion is a movement of the infrared imaging device initiated by a user to perform a NUC correction.

16. The device of claim 14, wherein the processor is adapted to:

detect the motion; and

select the set of the image frames based on the detected motion.

17. The device of claim 16, wherein the processor is adapted to evaluate pixels of the image frames to detect the motion.

18. The device of claim 16, further comprising a motion sensor, wherein the processor is adapted to monitor the motion sensor to detect the motion.

19. The device of claim 14, wherein the processor is adapted to temporally filter the captured image frames before the set of image frames is accumulated.

20. The device of claim 19, wherein the processor is adapted to:

compare a first image frame with a second image frame; and

detect motion based on an average change exhibited by neighborhoods of corresponding pixels in the first and second image frames.

21. The device of claim 13, wherein the blurred image frame is captured from the scene while the infrared imaging device is intentionally defocused.

22. The device of claim 13, wherein the scene is an environment in which the infrared imaging device is located.

23. The device of claim 13, wherein the device is a mobile device adapted to receive the infrared imaging device.

24. The device of claim 13, wherein the processor is part of the infrared imaging device.