Image stabilization systems and methods

• US 9,338,352 B2
• Filed: 12/27/2012
• Issued: 05/10/2016
• Est. Priority Date: 12/30/2011
• Status: Active Grant

• Current Assignee: Flir Systems AB (Teledyne Technologies Incorporated)
• Original Assignee: Flir Systems AB (Teledyne Technologies Incorporated)
• Inventors: Strandemar, Katrin
• Primary Examiner(s): Kelley, Christopher S
• Assistant Examiner(s): Beasley, Deirdre
• Application Number:
  US13/728,856
• Publication Number:
  US 20130169819A1
• Time in Patent Office: 1,230 Days
• US Class Current: 1/1
• CPC Class Codes: H04N 23/68 for stable pick-up of the scene, e.g. compensating for camera body vibrations
• 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

A method and systems of stabilizing a sequence of infrared (IR) images captured using an infrared (IR) imaging system, includes: generating edge information representations of selected captured IR images in said sequence; for each generated edge information representation, generating a second representation having a reduced amount of information compared to the edge information representation; determining displacements between captured IR images in relation to previous IR images in said sequence based on a comparison between said second representations; generating a stabilized sequence of IR images by shifting said captured IR images based on said determined displacements.

Claims

1. A method of stabilizing a sequence of infrared (IR) images captured using an infrared (IR) imaging system, using a processor comprised in said IR imaging system, wherein the processor is adapted to process IR image data, the method comprising:

for each of a first and a second IR image;

i) identifying, by said processor, pixels comprising edge information;

ii) generating, by said processor, an edge map, wherein the pixels identified as comprising edge information are assigned first pixel values that differ from second pixel values for the remaining pixels, and wherein the generating of an edge map further comprises applying one or more threshold values to the first and second IR images, respectively; and

iii) generating, by said processor, a data collection representing the distribution of the first and/or second pixel values in the edge map;

thus resulting in a first data collection representing the distribution of the first and/or second pixel values in the first edge map, and a second data collection representing the distribution of the first and/or second pixel values in the second edge map;

comparing, by said processor, the first data collection to the second data collection;

determining, by said processor, the displacement between said first and second IR images based on the comparison between the first and second data collections;

shifting, by said processor, the second IR image based on the determined displacement, thereby achieving stabilization of the second IR image to the IR first image; and

providing, by said processor, a feedback control loop adapted to optimize said one or more threshold values that are to be applied to the second IR image, in order to obtain an optimized number of, or an optimized amount of, pixels in the second IR image that will be identified as comprising edge information.

2. The method of claim 1, further comprising a selection or:

pre-filtering, by said processor, the first and second IR images in order to extract high frequency content before identifying pixels comprising edge information; and

pre-filtering, by said processor, the first and second selected IR images in order to remove noise from the image.

3. The method of claim 1, wherein

the data collection for each of the first and second IR images comprises the distribution of the first and/or second pixel values in the first image along an x-axis of the image and a y-axis of the image, respectively.

4. The method of claim 1, wherein the data collections for each of the first and second IR images are generated by applying Radon transformations to the edge information representations.

5. The method of claim 1, wherein comparing the first data collection to the second data collection comprises at least two comparisons, wherein, for each of the at least two sequent comparisons, the second data collection is shifted, by said processor, in relation to the first data collection or the first data collection is shifted in relation to the second data collection.

6. The method of claim 1, wherein said one or more threshold values are controlled, by said processor, such that the percentage of pixels in the second IR image that are identified as comprising edge information approaches a preset desired percentage value β

.

7. The method of claim 1, wherein said one or more threshold values are controlled, by said processor, based on the one or more threshold parameters applied on the first IR image and the percentage of pixels identified as comprising edge information in the first IR image.

13. A computer system having a processor being adapted to perform the steps or functions of claim 1.

14. A non-transitory computer-readable medium on which is stored information adapted to control a processor to perform the steps or functions of claim 1.

15. A computer program product stored on a non-transitory computer-readable medium comprising code portions adapted to control a processor to perform the steps or functions of claim 1.

16. A computer program product stored on a non-transitory computer-readable medium comprising configuration data adapted to configure a Field-Programmable Gate Array (FPGA) to ton perform the steps or functions of claim 1.

17. The method of claim 1, wherein:

said comparing the first data collection to the second data collection comprises

performing at least two comparisons between said first and second data collections, thereby generating a set of at least two differences; and

said determining the displacement between said first and second IR images comprises determining the displacement by identifying the minimum difference from the generated set of at least two differences.

8. An infrared (IR) imaging system, comprising:

an infrared sensor;

a processor adapted to process infrared image data from the infrared sensor depicting a scene, the processor being further adapted to;

receive a sequence of infrared (IR) images captured using an infrared (IR) imaging device;

for each of a first and a second IR image;

i) identify pixels comprising edge information;

ii) generate an edge map, wherein the pixels identified as comprising edge information are assigned first pixel values that differ from second pixel values for the remaining pixels, and wherein the generating of an edge map further comprises applying one or more threshold values to the first and second IR images, respectively; and

iii) generate a data collection representing the distribution of the first and/or second pixel values in the edge map;

thus resulting in a first data collection representing the distribution of the first and/or second pixel values in the first edge map, and a second data collection representing the distribution of the first and/or second pixel values in the second edge map;

compare the first data collection to the second data collection;

determine the displacement between said first and second IR images based on the comparison between the first and second data collections;

shift the second IR image based on the determined displacement, thereby achieving stabilization of the second IR image to the first IR image; and

provide a feedback control loop adapted to optimize said one or more threshold values that are to be applied to the second IR image, in order to obtain an optimized number of, or an optimized amount of, pixels in the second IR image that will be identified as comprising edge information.

9. The infrared (IR) imaging system of claim 8, further comprising a selection of:

a display component adapted to display the second IR image stabilized to the first IR image;

a memory component adapted to store image data the second IR image stabilized to the first IR image; and

an output component adapted to output the second IR image stabilized to the first IR image to a receiving unit.

10. The infrared (IR) imaging system of claim 8, wherein the processor is configurable using a hardware description language (HDL).

11. The infrared (IR) imaging system of claim 8, wherein the processor is a Field-programmable gate array (FPGA).

12. The infrared (IR) imaging system of claim 8, the processor further being adapted to:

pre-filter the first and second IR images in order to extract high frequency content before identifying pixels comprising edge information;

or

pre-filter the first and second IR images in order to remove noise from the image.