Comparison of infrared images

• US 8,599,264 B2
• Filed: 11/17/2010
• Issued: 12/03/2013
• Est. Priority Date: 11/20/2009
• Status: Active Grant

• Current Assignee: Fluke Corporation (Fortive Corp.)
• Original Assignee: Fluke Corporation (Fortive Corp.)
• Inventors: Schmidt, Roger
• Primary Examiner(s): Rao, Andy
• Assistant Examiner(s): ELAHI, SHAN E
• Application Number:
  US12/948,286
• Publication Number:
  US 20110122251A1
• Time in Patent Office: 1,112 Days
• Field of Search: 348/164, 348165-169
• US Class Current: 348/164
• CPC Class Codes: G06T 7/38 Registration of image sequences
• CPC Class Codes: G06V 10/143 Sensing or illuminating at different wavelengths
• CPC Class Codes: H04N 23/11 for generating image signals from visible and infrared light wavelengths

Abstract

Methods for comparing infrared image data and/or for generating infrared image comparison data are provided. In one method two image data sets are selected including visual-light and infrared image data from one or more points of view of a scene. Visual-light image data from each data set can be compared to determine an alignment correlation between different points of view for the visual-light data. The alignment correlation can then be used to correlate infrared image data from each data set. The correlated infrared image data can be compared to generate infrared comparison image data. Thermal imaging cameras capable of performing such methods are also provided.

Claims

1. A method for comparing infrared (IR) image data representative of a scene, comprising:

selecting a first image data set of a scene, the first image data set comprising first visual-light (VL) image data captured from a first VL point of view and first IR image data captured from a first IR point of view, the first VL point of view having a first known correlation to the first IR point of view;

selecting a second image data set of the scene, the second image data set comprising second VL image data captured from a second VL point of view and second IR image data captured from a second IR point of view, the second VL point of view having a second known correlation to the second IR point of view;

comparing the first VL image data to the second VL image data to determine an alignment correlation between the first VL point of view and the second VL point of view;

correlating the second IR image data with the first IR image data using the first and the second known correlations and the alignment correlation; and

comparing at least a portion of the first IR image data to a correlated portion of the second IR image data to generate IR comparison image data.

2. The method of claim 1, further comprising combining the IR comparison image data with the first VL image data or the second VL image data to produce a VL and IR composite comparison image.

3. The method of claim 1, wherein comparing the portion of the first IR image data with the correlated portion of the second IR image data comprises subtracting the correlated portion of the second IR image data from the portion of the first IR image data.

4. The method of claim 1, further comprising correlating the IR comparison image data with temperature difference.

5. The method of claim 1, further comprising thresholding the IR comparison image data to identify a subset of the IR comparison image data exceeding a threshold temperature difference.

6. The method of claim 1, wherein the first known correlation is the same as the second known correlation.

7. The method of claim 1, wherein the first known correlation is fixed.

8. A non-transitory computer-readable storage medium having computer-executable instructions for performing a method for generating infrared (IR) comparison image data, the method comprising:

selecting a first image data set of a scene, the first image data set comprising first visual-light (VL) image data captured from a first VL point of view and first IR image data captured from a first IR point of view, the first VL point of view having a first known correlation to the first IR point of view;

selecting a second image data set of the scene, the second image data set comprising second VL image data captured from a second VL point of view and second IR image data captured from a second IR point of view, the second VL point of view having a second known correlation to the second IR point of view;

comparing the first VL image data to the second VL image data to determine an alignment correlation between the first VL point of view and the second VL point of view;

correlating the second IR image data with the first IR image data using the first and the second known correlations and the alignment correlation; and

comparing at least a portion of the first IR image data to a correlated portion of the second IR image data to generate IR comparison image data.

9. The non-transitory computer-readable storage medium of claim 8, wherein comparing the portion of the first IR image data with the correlated portion of the second IR image data comprises subtracting the correlated portion of the second IR image data from the portion of the first IR image data.

10. An infrared (IR) imaging camera, comprising:

a visible-light (VL) camera module having a VL sensor for capturing VL image data from a scene;

an IR camera module having an IR sensor for capturing IR image data from the scene, the IR camera module having a known spatial correlation to the VL camera module;

a display for displaying at least a portion of the VL image data and/or at least a portion of the IR image data; and

a programmable processor coupled with the display and the IR and the VL camera modules, the processor programmed with instructions for

(a) selecting a first image data set of the scene, the first image data set comprising first VL image data captured by the VL camera module from a first VL point of view and first IR image data captured by the IR camera module from a first IR point of view, the first VL and the first IR points of view related by the known spatial correlation,

(b) selecting a second image data set of the scene, the second image data set comprising second VL image data captured by the VL camera module from a second VL point of view and second IR image data captured by the IR camera module from a second IR point of view, the second VL and the second IR points of view related by the known spatial correlation, and

(c) generating IR comparison image data from the first and the second IR image data, comprising

(1) comparing the first VL image data to the second VL image data to determine an alignment correlation between the first VL point of view and the second VL point of view,

(2) correlating the second IR image data with the first IR image data using the known spatial correlation and the alignment correlation, and

(3) comparing at least a portion of the first IR image data to a correlated portion of the second IR image data to generate the IR comparison image data.

11. The method of claim 10, wherein comparing the portion of the first IR image data with the correlated portion of the second IR image data comprises subtracting the correlated portion of the second IR image data from the portion of the first IR image data.

12. The method of claim 10, further comprising correlating the IR comparison image data with temperature difference.

13. The method of claim 10, further comprising thresholding the IR comparison image data to identify a subset of the IR comparison image data exceeding a threshold temperature difference.

14. A method of tracking localized temperature changes within a scene, comprising:

capturing at a first instant first visual-light (VL) image data of a scene and first infrared (IR) image data of the scene, the first IR image data being indicative of localized temperatures within the scene at the first instant;

capturing at a second instant second VL image data of the scene and second IR image data of the scene, the second IR image data being indicative of the localized temperatures within the scene at the second instant;

determining an alignment correlation between the first and the second VL image data;

correlating the second IR image data with the first IR image data using the alignment correlation;

comparing at least a portion of the first IR image data to a correlated portion of the second IR image data to generate IR comparison image data indicative of differences between the localized temperatures within the scene at the first instant and the second instant; and

displaying at least a portion of the IR comparison image data.

15. The method of claim 14, wherein comparing the portion of the first IR image data with the correlated portion of the second IR image data comprises subtracting the correlated portion of the second IR image data from the portion of the first IR image data.

16. The method of claim 14, further comprising thresholding the IR comparison image data to identify a subset of the IR comparison image data exceeding a threshold temperature difference.

17. The method of claim 16, wherein displaying the at least a portion of the IR comparison image data comprises displaying only the subset of the IR comparison image data exceeding the threshold temperature difference.

18. The method of claim 14, further comprising combining the IR comparison image data with the first VL image data or the second VL image data to produce a VL and IR composite comparison image.