Image shifting apparatus for enhanced image resolution

• US 7,420,592 B2
• Filed: 06/17/2004
• Issued: 09/02/2008
• Est. Priority Date: 06/17/2004
• Status: Expired due to Fees

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Freeman, Philip L.
• Primary Examiner(s): Ometz; David
• Assistant Examiner(s): Negron; Wanda M
• Application Number:
  US10/870,604
• Publication Number:
  US 20050280714A1
• Time in Patent Office: 1,538 Days
• Field of Search: 348/219.1
• US Class Current: 348/219.1
• CPC Class Codes: G09G 3/007 Use of pixel shift techniques, e.g. by mechanical shift of the physical pixels or by optical shift of the perceived pixels
• CPC Class Codes: H04N 25/48 Increasing resolution by shifting the sensor relative to the scene

Abstract

An image shifting apparatus may capture multiple frames of an image, with each frame offset by a sub-pixel offset distance. After capture, the various sub-pixel offset images may be registered together and analyzed using known resolution enhancement algorithms. Super resolution algorithms, for example. may take the various frames and perform edge identification and peak extraction routines to improve the resolution of high frequency data within an image. The image shifting apparatus may include an actuation controlled optical compensator within the imaging system that may be adjusted to create a sub-pixel offset image of an original reference image. The optical compensator may be an image-stabilizing element, for example, capable of forming sub-pixel shifts in an image plane.

Claims

1. A method of enhancing resolution of an image, the method comprising:

providing a photodetector;

capturing a first image at a first pixel position on the photodetector;

integrating a signal from a vibration sensor to determine image shift due to motion of an optical element;

calculating an amount of offset for an optical compensator to shift the first image a predetermined sub-pixel amount including the image shift due to the motion of the optical element;

providing a sub-pixel offset signal to the optical compensator in the calculated amount of the offset;

moving the optical compensator to form at least one additional image at a second pixel position offset from the first pixel position by a sub-pixel offset distance;

capturing the at least one additional image;

comparing the first image to the at least one additional image;

in response to the comparison of the first image and the at least one additional image, deriving an enhanced resolution image; and

identifying an edge in the enhanced resolution image, the edge having varying intensities based on the comparison of the first image and the at least one additional image;

determining a region of peak intensity for the edge of the enhanced resolution image; and

in response to the determination of the region of peak intensity, enhancing a resolution of the edge by narrowing the edge to the peak intensity region.

2. The method of claim 1, further comprising moving the optical compensator to form the at least one additional image at the second pixel position offset from the first pixel position by a distance equal to or less than approximately 1/10 of a pixel on the photodetector.

3. The method of claim 2, wherein the distance is equal to or less than approximately 1/100 of the pixel.

4. The method of claim 1, further comprising:

forming the enhanced resolution image to have a 10×

resolution enhancement in each orthogonal direction of the enhanced resolution image.

5. An article comprising a machine-accessible medium having stored thereon instructions that, when executed by a machine, cause the machine to:

capture a first image at a first pixel position;

integrate a signal from a vibration sensor;

provide a sub-pixel offset signal to an optical compensator based on a requested image shift and an amount of image shift calculated from the vibration sensor;

move the optical compensator to form at least one additional image at a second pixel position offset from the first pixel position by a sub-pixel offset distance;

capture the at least one additional image;

compare the first image to the at least one additional image;

in response to a comparison of the first image and the at least one additional image, derive an enhanced resolution image;

identify an edge in the enhanced resolution image, the edge having varying intensities based on the comparison of the first image and the at least one additional image;

determine a region of peak intensity for the edge of the enhanced resolution image; and

in response to the determination of the region of peak intensity, enhance a resolution of the edge by narrowing the edge to the peak intensity region.

6. The article of claim 5, having further instructions that when executed by the machine, cause the machine to create the enhanced resolution image having a 10×

resolution enhancement in each orthogonal direction of the enhanced resolution image.

7. The article of claim 5, having further instructions that when executed by the machine, cause the machine to apply a Sobel, Prewitt, Canny, or SUSAN filter to identify the edge.

8. The article of claim 5, having further instructions that when executed by the machine, cause the machine to calibrate the optical compensator.

9. The article of claim 8, having further instructions that when executed by the machine, cause the machine to:

move the optical compensator an offset distance to produce a calibration image at a calibrated offset position, having a predetermined pixel separation from the first pixel position;

determining a position adjustment signal corresponding to the offset distance; and

deriving a sub-pixel offset signal mapping.

10. The article of claim 5, having further instructions that when executed by the machine, cause the machine to register the first image and the at least one additional image.

11. The article of claim 5, having further instructions that when executed by the machine, cause the machine to move the optical compensator to form the at least one additional image at the second pixel position offset from the first pixel position by a distance equal to or less than approximately 1/10 of a pixel on a pixel array.

12. The article of claim 5, having further instructions that when executed by the machine, cause the machine to move the optical compensator to form the at least one additional image at the second pixel position offset from the first pixel position by a distance equal to or less than approximately 1/100 of a pixel on a pixel array.