METHOD FOR MINIMIZING SCINTILLATION IN DYNAMIC IMAGES

• US 20130343671A1
• Filed: 08/23/2013
• Published: 12/26/2013
• Est. Priority Date: 05/30/2008
• Status: Active Grant

• Current Assignee: DRS Network & Imaging Systems, LLC (Leonardo S.p.A.)
• Original Assignee: DRS RSTA Incorporated (Leonardo S.p.A.)
• Inventors: Lee, Harry C., Pace, Teresa L., Fuentes, Marlon J.
• Granted Patent: US 8,768,092 B2
• Time in Patent Office: Days
• US Class Current: 382/274
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 2207/20021 Dividing image into blocks, subimages or windows
• CPC Class Codes: G06T 2207/20192 Edge enhancement; Edge preservation
• CPC Class Codes: G06T 2207/20208 High dynamic range [HDR] image processing
• CPC Class Codes: G06T 2207/20216 Image averaging
• CPC Class Codes: G06T 2207/20221 Image fusion; Image merging
• CPC Class Codes: G06T 2207/20224 Image subtraction
• CPC Class Codes: G06T 2207/30181 Earth observation
• CPC Class Codes: G06T 5/00 Image enhancement or restoration
• CPC Class Codes: G06T 5/003 Deblurring; Sharpening vibration or motion blur correction for cameras comprising an electronic image sensor H04N23/682
• CPC Class Codes: G06T 5/008 Local, e.g. shadow enhancement
• CPC Class Codes: G06T 5/40 using histogram techniques
• CPC Class Codes: G06T 5/50 using two or more images, e.g. averaging or subtraction
• CPC Class Codes: G06T 5/73 Deblurring; Sharpening
• CPC Class Codes: G06T 5/94 based on local image properties, e.g. for local contrast enhancement
• CPC Class Codes: G06V 10/30 Noise filtering

Abstract

A method for reducing scintillation in an image of a scene includes receiving an input sequence of images of the scene and grouping a first plurality of images of the sequence of images into a first subset of images comprising a first number of images that occur in sequence within the input sequence of images of the scene. The method also includes grouping a second plurality of images of the sequence of images into a second subset of images comprising a second number of images that occur in sequence within the input sequence of images of the scene. The method further includes generating a set of averaged images comprising an averaged image for the first subset of images and an averaged image for the second subset of image and outputting a composite image based at least the set of averaged images.

Claims

1. A method for reducing scintillation in an image of a scene, the method comprising:

receiving an input sequence of images of the scene;

grouping a first number of images that occur in sequence within the input sequence of images of the scene into a first subset of images;

grouping a second number of images that occur in sequence within the input sequence of images of the scene into a second subset of images;

generating a first combined image by applying an arithmetic algorithm to the first subset of images;

generating a second combined image by applying the arithmetic algorithm to the second subset of images;

creating a composite mask based on at least the first combined image and the second combined image;

generating a composite image using the composite mask and at least one of the first combined image or the second combined image; and

outputting the composite image.

2. The method of claim 1 wherein the arithmetic algorithm comprises an averaging algorithm.

3. The method of claim 1 comprising:

grouping a third number of images that occur in sequence within the input sequence of images of the scene into a third subset of images; and

generating a third combined image by applying the arithmetic algorithm to the third subset of images;

wherein creating a composite mask is based on at least the first combined image, the second combined image, and the third combined image, and generating a composite image uses the composite mask and at least one of the first combined image, the second combined image, or the third combined image.

4. The method of claim 3 wherein creating a composite mask comprises:

generating a first difference image by subtracting the second combined image from the first combined image;

generating a second difference image by subtracting the third combined image from the first combined image; and

creating the composite mask based on at least the first difference image and the second difference image.

5. The method of claim 4 wherein creating a composite mask comprises:

generating a combined difference image by summing at least the first difference image and the second difference image;

creating a first mask by applying a first threshold value to the combined difference image;

creating a second mask by apply a second threshold value to the first difference image;

creating a third mask by apply a third threshold value to the second difference image; and

summing at least the first mask, the second mask, and the third mask to produce the composite mask.

6. The method of claim 5 wherein the first threshold value is different from the second threshold value and the third threshold value.

7. The method of claim 3 wherein generating a composite image comprises:

creating an image offset by overlaying one of at least the first combined image, the second combined image, or the third combined image over the composite mask;

generating an intermediate image by removing at least one region determined by the composite mask from the first combined image; and

combining the image offset with the intermediate image to produce the composite image.

8. The method of claim 3 wherein the first subset of images includes the second subset of images and the third subset of images.

9. A non-transitory computer-readable storage medium comprising a plurality of computer-readable instructions tangibly embodied therein, the plurality of computer-readable instructions comprising:

instructions that cause the processor to receive an input sequence of images of the scene;

instructions that cause the processor to group a first number of images that occur in sequence within the input sequence of images of the scene into a first subset of images;

instructions that cause the processor to group a second number of images that occur in sequence within the input sequence of images of the scene into a second subset of images;

instructions that cause the processor to generate a first combined image by applying an arithmetic algorithm to the first subset of images;

instructions that cause the processor to generate a second combined image by applying the arithmetic algorithm to the second subset of images;

instructions that cause the processor to create a composite mask based on at least the first combined image and the second combined image;

instructions that cause the processor to generate a composite image using the composite mask and one of at least the first combined image or the second combined image; and

instructions that cause the processor to output the composite image.

10. The non-transitory computer-readable storage medium of claim 9 wherein the arithmetic algorithm comprises an averaging algorithm.

11. The non-transitory computer-readable storage medium of claim 9 wherein the plurality of computer-readable instructions comprises:

instructions that cause the processor to group a third number of images that occur in sequence within the input sequence of images of the scene into a third subset of images; and

instructions that cause the processor to generate a third combined image by applying the arithmetic algorithm to the third subset of images;

wherein creating a composite mask is based on at least the first combined image, the second combined image, and the third combined image, and generating a composite image uses the composite mask and at least one of the first combined image, the second combined image, or the third combined image.

12. The non-transitory computer-readable storage medium of claim 11 wherein the instructions that cause the processor to generate a composite mask comprises:

instructions that cause the processor to generate a first difference image by subtracting the second combined image from the first combined image;

instructions that cause the processor to generate a second difference image by subtracting the third combined image from the first combined image; and

instructions that cause the processor to create the composite mask based on at least the first difference image and the second difference image.

13. The non-transitory computer-readable storage medium of claim 12 the instructions that cause the processor to generate a composite mask comprises:

instructions that cause the processor to generate a combined difference image by summing at least the first difference image and the second difference image;

instructions that cause the processor to create a first mask by applying a first threshold value to the combined difference image;

instructions that cause the processor to create a second mask by apply a second threshold value to the first difference image;

instructions that cause the processor to create a third mask by apply a third threshold value to the second difference image; and

instructions that cause the processor to sum at least the first mask, the second mask, and the third mask to produce the composite mask.

14. The non-transitory computer-readable storage medium of claim 11 wherein instructions that cause the processor to generate a composite image comprises:

instructions that cause the processor to create an image offset by overlaying one of at least the first combined image, the second combined image, or the third combined image over the composite mask;

instructions that cause the processor to generate an intermediate image by removing at least one region determined by the composite mask from the first combined image; and

instructions that cause the processor to combine the image offset with the intermediate image to produce the composite image.

15. The non-transitory computer-readable storage medium of claim 11 wherein the first subset of images includes the second subset of images and the third subset of images.

16. The non-transitory computer-readable storage medium of claim 11 wherein the second subset of images and the third subset of images have one or more overlapping images.

17. An imaging system, comprising:

a memory; and

an image processing unit coupled to the memory;

wherein the processing unit is configured to execute a method for reducing scintillation in an image of a scene, the method comprising;

receiving an input sequence of images of the scene;

grouping a first number of images that occur in sequence within the input sequence of images of the scene into a first subset of images;

grouping a second number of images that occur in sequence within the input sequence of images of the scene into a second subset of images;

generating a first combined image by applying an arithmetic algorithm to the first subset of images;

generating a second combined image by applying the arithmetic algorithm to the second subset of images;

creating a composite mask based on at least the first combined image and the second combined image;

generating a composite image using the composite mask and one of at least the first combined image or the second combined image; and

outputting the composite image.

18. The system of claim 17 wherein the arithmetic algorithm comprises an averaging algorithm.

19. The system of claim 17 wherein the method comprises:

grouping a third number of images that occur in sequence within the input sequence of images of the scene into a third subset of images; and

generating a third combined image by applying the arithmetic algorithm to the third subset of images;

wherein creating a composite mask is based on at least the first combined image, the second combined image, and the third combined image, and generating a composite image uses the composite mask and at least one of the first combined image, the second combined image, or the third combined image.

20. The system of claim 19 wherein creating a composite mask comprises:

generating a first difference image by subtracting the second combined image from the first combined image;

generating a second difference image by subtracting the third combined image from the first combined image; and

creating the composite mask based on at least the first difference image and the second difference image.

21. The system of claim 20 creating a composite mask comprises:

generating a combined difference image by summing at least the first difference image and the second difference image;

creating a first mask by applying a first threshold value to the combined difference image;

creating a second mask by apply a second threshold value to the first difference image;

creating a third mask by apply a third threshold value to the second difference image; and

summing at least the first mask, the second mask, and the third mask to produce the composite mask.

22. The system of claim 19 wherein generating a composite image comprises:

creating an image offset by overlaying one of at least the first combined image, the second combined image, or the third combined image over the composite mask;

generating an intermediate image by removing at least one region determined by the composite mask from the first combined image; and

combining the image offset with the intermediate image to produce the composite image.

23. The system of claim 19 wherein the first subset of images includes the second subset of images and the third subset of images.