Infrared and near-infrared camera hyperframing

• US 7,606,484 B1
• Filed: 03/23/2006
• Issued: 10/20/2009
• Est. Priority Date: 03/23/2006
• Status: Active Grant

• Current Assignee: FLIR Systems, Inc. (Teledyne Technologies Incorporated)
• Original Assignee: FLIR Systems, Inc. (Teledyne Technologies Incorporated)
• Inventors: D'Souza, Shariff, Richards, Austin A.
• Primary Examiner(s): Mahoney; Christopher E
• Assistant Examiner(s): Strieb; Michael A
• Application Number:
  US11/388,711
• Time in Patent Office: 1,307 Days
• Field of Search: 396335-338, 396/340, 396/18, 396/322, 396/323, 396/353, 396/265, 396/333, 356/51
• US Class Current: 396/322
• CPC Class Codes: G01J 2005/0077 Imaging
• CPC Class Codes: G01J 5/602 using selective, monochromatic or bandpass filtering
• CPC Class Codes: G03B 41/00 Special techniques not covered by groups G03B31/00 - G03B39/00; Apparatus therefor
• CPC Class Codes: H04N 23/70 Circuitry for compensating brightness variation in the scene
• CPC Class Codes: H04N 23/741 by increasing the dynamic range of the image compared to the dynamic range of the electronic image sensors
• CPC Class Codes: H04N 23/75 by influencing optical camera components
• 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

Systems and techniques for improving the dynamic range of infrared detection systems. For example, a mechanical superframing technique may comprise positioning a first filter in the optical path of an infrared camera at a first time, receiving infrared light from an object through the first filter at a detector array, acquiring first subframe image data for the object, positioning a second filter in the optical path of the infrared camera at a later time, receiving infrared light from the object through the second filter, acquiring second subframe image data for the object, and generating first superframe data based on at least some of the first subframe image data and at least some of the second subframe image data.

Claims

1. An article comprising a machine-readable medium embodying information indicative of instructions that when performed by one or more machines result in operations comprising:

positioning a first filter in an optical path of an infrared camera at a first time;

receiving infrared light from an object through the first filter at a detector array of the infrared camera;

acquiring first subframe image data for the object using a first integration time based on the receiving the infrared light from the object through the first filter at the detector array;

positioning a second filter in the optical path of the infrared camera at a second later time;

receiving infrared light from the object through the second filter at the detector array;

acquiring second subframe image data for the object using the first integration time based on the receiving the infrared light from the object through the second filter at the detector array; and

generating first superframe image data based on at least some of the first subframe image data and at least some of the second subframe image data.

2. The article of claim 1, wherein the first filter and the second filter comprise different neutral density filters.

3. The article of claim 1, wherein the operations further comprise:

receiving infrared light at the detector array from the object;

acquiring third subframe image data for the object using a second integration time different from the first integration time based on the receiving the infrared light from the object at the detector array;

receiving infrared light at the detector array from the object; and

acquiring fourth subframe image data for the object using a third integration time different from the first and second integration times based on the receiving the infrared light from the object at the detector array;

wherein the generating first superframe image data is further based on at least some of the third subframe image data and at least some of the fourth subframe image data.

4. The article of claim 3, wherein the generating first superframe image data comprises for each pixel selecting from the first, second, third, or fourth subframe image data depending upon which provides a greater sensitivity without exceeding a saturation threshold.

5. The article of claim 4, wherein the operations further comprise performing saturation mitigation if the saturation threshold is exceeded for a lowest sensitivity from the first, second, third, and fourth subframe image data.

6. The article of claim 3, wherein the acquiring first and second subframe image data is based on a mechanical superframing technique, while the acquiring third and fourth subframe image data is based on an electronic superframing technique, and wherein the operations further comprise positioning at least one filter in the optical path of the infrared camera during the acquiring of the third and fourth subframe image data.

7. The article of claim 1, wherein the first filter is configured to attenuate a first amount of light and the second filter is configured to attenuate a second larger amount of light, and wherein generating first superframe image data based on at least some of the first subframe image data and the second subframe image data comprises generating a first pixel portion of the first superframe image data using a first pixel portion of the first subframe data if the first pixel portion of the first subframe data does not exceed a saturation threshold amount.

8. The article of claim 1, wherein the infrared camera is a near-infrared (NIR) camera.

9. The article of claim 1, wherein the generating first superframe image data comprises for each pixel selecting from the first subframe image data or the second subframe image data depending upon which provides a greater sensitivity without exceeding a saturation threshold.

10. The article of claim 1, wherein the operations further comprise:

positioning a third filter in the optical path of the infrared camera along with the first filter, the third filter configured to pass a narrow wavelength band including a first wavelength;

wherein the first subframe image data is associated with the first wavelength at the detector array using a first exposure;

positioning the third filter in the optical path of the infrared camera along with the second filter;

wherein the second subframe image data is associated with the first wavelength at the detector using a second exposure;

wherein the first superframe image data is associated with the first wavelength;

positioning a fourth filter in the optical path of the infrared camera along with the first filter, the fourth filter configured to pass a narrow wavelength band including a second different wavelength;

acquiring third subframe image data associated with the second wavelength at the detector array using the first exposure;

positioning the fourth filter in the optical path of the infrared camera along with the second filter;

acquiring fourth subframe image data associated with the second wavelength at the detector array using the second exposure;

generating second superframe image data associated with the second wavelength based on at least some of the third subframe image data and at least some of the fourth subframe image data; and

determining one or more physical properties of one or more graybodies using the first superframe image data and the second superframe image data.

11. The article of claim 10, wherein the one or more physical properties comprises a temperature.

12. A method comprising:

positioning a first filter in an optical path of an infrared camera at a first time;

receiving infrared light from an object through the first filter at a detector array of the infrared camera;

acquiring first subframe image data for the object using a first integration time based on the receiving the infrared light from the object through the first filter at the detector array;

positioning a second filter in the optical path of the infrared camera at a second later time;

receiving infrared light from the object through the second filter at the detector array;

acquiring second subframe image data for the object using the first integration time based on the receiving the infrared light from the object through the second filter at the detector array; and

generating first superframe image data based on at least some of the first subframe image data and at least some of the second subframe image data.

13. The method of claim 12, wherein the first filter and the second filter comprise different neutral density filters.

14. The method of claim 12, further comprising:

receiving infrared light at the detector array from the object;

acquiring third subframe image data for the object using a second integration time different from the first integration time based on the receiving the infrared light from the object at the detector array;

receiving infrared light at the detector array from the object; and

acquiring fourth subframe image data for the object using a third integration time different from the first and second integration times based on the receiving the infrared light from the object at the detector array;

wherein the generating first superframe image data is further based on at least some of the third subframe image data and at least some of the fourth subframe image data.

15. The method of claim 14, wherein the generating first superframe image data comprises for each pixel selecting from the first, second, third, or fourth subframe image data depending upon which provides a greater sensitivity without exceeding a saturation threshold.

16. The method of claim 15, wherein the operations further comprise performing saturation mitigation if the saturation threshold is exceeded for a lowest sensitivity from the first, second, third, and fourth subframe image data.

17. The method of claim 14, wherein the acquiring first and second subframe image data is based on a mechanical superframing technique, while the acquiring third and fourth subframe image data is based on an electronic superframing technique, and wherein the method further comprises positioning at least one filter in the optical path of the infrared camera during the acquiring of the third and fourth subframe image data.

18. The method of claim 12, wherein the first filter is configured to attenuate a first amount of light and the second filter is configured to attenuate a second larger amount of light, and wherein generating first superframe image data based on at least some of the first subframe image data and the second subframe image data comprises generating a first pixel portion of the first superframe image data using a first pixel portion of the first subframe data if the first pixel portion of the first subframe data does not exceed a saturation threshold amount.

19. The method of claim 12, wherein the infrared camera is a near-infrared (NIR) camera.

20. The method of claim 12, wherein the generating first superframe image data comprises for each pixel selecting from the first subframe image data or the second subframe image data depending upon which provides a greater sensitivity without exceeding a saturation threshold.

21. The method of claim 12, wherein the method further comprises:

positioning a third filter in the optical path of the infrared camera along with the first filter, the third filter configured to pass a narrow wavelength band including a first wavelength;

wherein the first subframe image data is associated with the first wavelength at the detector array using a first exposure;

positioning the third filter in the optical path of the infrared camera along with the second filter;

wherein the second subframe image data is associated with the first wavelength at the detector using a second exposure;

wherein the first superframe image data is associated with the first wavelength;

positioning a fourth filter in the optical path of the infrared camera along with the first filter, the fourth filter configured to pass a narrow wavelength band including a second different wavelength;

acquiring third subframe image data associated with the second wavelength at the detector array using the first exposure;

positioning the fourth filter in the optical path of the infrared camera along with the second filter;

acquiring fourth subframe image data associated with the second wavelength at the detector array using the second exposure;

generating second superframe image data associated with the second wavelength based on at least some of the third subframe image data and at least some of the fourth subframe image data; and

determining one or more physical properties of one or more graybodies using the first superframe image data and the second superframe image data.

22. The method of claim 21, wherein the one or more physical properties comprises a temperature.

23. An infrared camera system comprising:

a filter holder configured to hold a plurality of filters and to position each of the filters in turn in an optical path of the infrared camera system;

a detection system configured to receive light through a first filter of the plurality of filters positioned in the optical path of the infrared camera at a first time and to generate first subframe information using a first integration time based on the light from an object received through the first filter at the detection system, and further configured to receive light through a second filter of the plurality of filters positioned in the optical path of the infrared camera at a second later time and to generate second subframe information indicative thereof using the first integration time based on the light from the object received through the second filter at the detection system; and

a processor configured to receive the first subframe information and the second subframe information and to generate first superframe information based on at least a part of the first subframe information and the second subframe information.

24. The system of claim 23, wherein the detection system is a near-infrared (NIR) detection system, and wherein the detection system is further configured to receive light to generate third subframe information from the object using a second integration time different from the first integration time, and further configured to receive light to generate fourth subframe information from the object using a third integration time different from the first and second integration times, and

wherein the processor is configured to receive the third and fourth subframe information and to generate the first superframe information which is further based on at least a part of the third superframe information and the fourth superframe information.

25. The system of claim 24, wherein the first superframe information is generated for each pixel by selecting from the first, second, third, or fourth subframe information depending upon which provides a greater sensitivity without exceeding a saturation threshold.

26. The system of claim 25, wherein the processor is configured to perform saturation mitigation if the saturation threshold is exceeded for a lowest sensitivity from the first, second, third, and fourth subframe information.

27. The system of claim 24, wherein the first and second subframe information is generated based on a mechanical superframing technique, while the third and fourth subframe information is generated based on an electronic superframing technique, and wherein the filter holder is configured to position at least one filter in the optical path of the infrared camera system during the generation of the third and fourth subframe information.

28. The system of claim 23, wherein the plurality of filters includes at least one neutral density filter.

29. The system of claim 23, wherein the plurality of filters includes at least one bandpass filter.

30. The system of claim 29, wherein the at least one bandpass filter comprises a spike filter.

31. The system of claim 23, further comprising a motor configured to exert torque on the filter holder.

32. The system of claim 31, wherein the filter holder is generally wheel-shaped, and wherein the motor is configured to exert a torque on the filter holder to cause the filter holder to rotate with a first frequency.

33. The system of claim 23, wherein at least a portion of the processor is included in a computer separate from a camera housing containing the filter holder.

34. The system of claim 23, wherein at least a portion of the processor is included in a camera housing of the infrared camera system.

35. The system of claim 23, wherein the first superframe information is generated for each pixel by selecting from the first subframe information or the second subframe information depending upon which provides a greater sensitivity without exceeding a saturation threshold.

36. The system of claim 23, further comprising:

a second filter holder configured to hold a second plurality of filters and to position each in turn in the optical path of the infrared camera system;

wherein the detection system is configured to generate the first subframe information based on light received through the first filter and through a third filter of the second filter holder, the third filter configured to pass a narrow wavelength band including a first wavelength, the first filter configured to provide a first exposure;

wherein the detection system is configured to generate the second subframe information based on light received through the second filter and through the third filter of the second filter holder, and wherein the first superframe information is associated with the first wavelength, the second filter configured to provide a second exposure;

wherein the detection system is configured to receive light through the first filter and a fourth filter of the second filter holder positioned in the optical path of the infrared camera system and to generate third subframe information using the first exposure, the fourth filter configured to pass a narrow wavelength band including a second wavelength;

wherein the detection system is configured to receive light through the second filter and the fourth filter of the second filter holder positioned in the optical path of the infrared camera system and to generate fourth subframe information using the second exposure; and

wherein the processor is configured to receive the third subframe information and the fourth subframe information and generate second superframe information associated with the second wavelength, the processor configured to determine one or more physical properties of the object based on the first, second, third, and fourth subframe information.

37. The system of claim 36, wherein the one or more physical properties comprises a temperature.