Method of shutterless non-uniformity correction for infrared imagers

• US 9,508,124 B2
• Filed: 12/09/2015
• Issued: 11/29/2016
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: DRS Network & Imaging Systems, LLC (Leonardo S.p.A.)
• Original Assignee: DRS Network & Imaging Systems, LLC (Leonardo S.p.A.)
• Inventors: Bailey, John R., Allred, Rustin W.
• Primary Examiner(s): Alavi, Amir
• Application Number:
  US14/964,165
• Publication Number:
  US 20160086315A1
• Time in Patent Office: 356 Days
• US Class Current: 1/1
• CPC Class Codes: G06T 2207/10048 Infrared image
• CPC Class Codes: G06T 5/00 Image enhancement or restoration
• CPC Class Codes: G06T 5/77 Retouching; Inpainting; Scratch removal
• CPC Class Codes: G06T 7/13 Edge detection
• CPC Class Codes: G06T 7/20 Analysis of motion motion estimation for coding, decoding, compressing or decompressing digital video signals H04N19/43, H04N19/51
• 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 of correcting an infrared image including a plurality of pixels arranged in an input image array, a first pixel in the plurality of pixels having a first pixel value and one or more neighbor pixel with one or more neighbor pixel values. The first pixel and the one or more neighbor pixels are associated with an object in the image. The method includes providing a correction array having a plurality of correction pixel values, generating a corrected image array by adding the first pixel value to a correction pixel value in the correction array, and detecting edges in the corrected image array. The method also includes masking the detected edges in the corrected image array, updating the correction array, for each correction pixel value in the correction array and providing an output image array based on the correction array and the input image array.

Claims

1. A method of correcting an infrared image, the method comprising:

providing a processor;

receiving the infrared image from a camera, the infrared image comprising a plurality of pixels arranged in an input image array, a first pixel in the plurality of pixels having a first pixel value and one or more neighbor pixels with one or more neighbor pixel values, wherein the first pixel and the one or more neighbor pixels are associated with an object in the image, the one of more neighbor pixels being adjacent to the first pixel in the input image array;

providing a correction array having a plurality of correction pixel values;

generating a corrected image array by adding the first pixel value to a correction pixel value in the correction array;

detecting edges in the corrected image array;

masking the detected edges in the corrected image array;

updating, by the processor, the correction array, for each correction pixel value in the correction array; and

providing an output image array based on the correction array and the input image array.

2. The method of claim 1 further comprising determining that the camera is moving.

3. The method of claim 2 wherein determining that the camera is moving comprises using a motion sensor in the camera.

4. The method of claim 2 wherein determining that the camera is moving comprises using image processing-based techniques.

5. The method of claim 1 wherein updating the correction array comprises:

determining that the first pixel value is not an edge;

for each of the one or more neighbor pixel values, determining that the neighbor pixel value is not an edge;

computing a difference between the first pixel value and the one or more neighbor pixel values; and

updating the correction pixel values based on the difference.

6. The method of claim 5 wherein updating the correction array further comprises determining that an absolute value of the difference is within a range.

7. The method of claim 5 wherein updating the correction pixel values based on the difference comprises dividing the difference by a denominator, wherein the denominator is a predetermined value.

8. The method of claim 5 wherein updating the correction pixel values in the correction array comprises:

adding the difference to a previous neighbor correction value to update a neighbor correction value; and

subtracting the difference from a previous correction value to update a correction value.

9. The method of claim 8 wherein a sum of a first portion of the difference and a second portion of the difference is equal to the difference.

10. The method of claim 1 wherein the infrared image from the camera is a raw image, and the input image array comprises multiplying the raw image by a gain array, wherein the gain array is a predetermined array of values.