Method and apparatus for correction of an image from a fisheye lens in a camera

• US 9,531,923 B2
• Filed: 02/18/2015
• Issued: 12/27/2016
• Est. Priority Date: 01/30/2009
• Status: Expired due to Fees

• Current Assignee: Panasonic Automotive Systems Company of America (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Automotive Systems Company of America (Panasonic Holdings Corporation)
• Inventors: Hickerson, Dallas Dwight
• Primary Examiner(s): NGUYEN, MINH CHAU
• Application Number:
  US14/625,041
• Publication Number:
  US 20150163380A1
• Time in Patent Office: 678 Days
• Field of Search: 348/36, 348/148, 348/340
• US Class Current: 1/1
• CPC Class Codes: G06T 3/047 Fisheye or wide-angle transformations
• CPC Class Codes: G06T 5/80 Geometric correction
• CPC Class Codes: H04N 25/60 Noise processing, e.g. detecting, correcting, reducing or removing noise

Abstract

A method of operating a video system includes receiving an image captured by use of a fisheye lens. The image is divided into a plurality of horizontal image lines. A respective fraction of each of the horizontal image lines is sampled with a different respective sampling frequency. Each sampling frequency is inversely related to a size of the sampled fraction. The size of the sampled fraction increases with each horizontal image line in a progression from a top of the image to a bottom of the image.

Claims

1. A method of operating a video system, comprising the steps of:

receiving a first image captured by use of a fisheye lens;

dividing the image into a plurality of horizontal image lines, each image line having a middle portion and two lateral portions, a size of the middle portion relative to the lateral portions increasing with each horizontal image line from a top of the image to a bottom of the image;

discarding the lateral portions of the image lines;

representing each of the middle portions by a substantially equal number of samples; and

forming a second image including the samples.

2. The method of claim 1 wherein the representing step includes sampling a respective said middle portion of each of the image lines with a different respective sampling frequency, each sampling frequency being inversely related to a fraction of the respective image line occupied by the middle portion.

3. The method of claim 2 comprising the further steps of:

counting the horizontal image lines;

counting the number of pixels in each said image line; and

determining times at which to begin and end the sampling of each line, the determining being based upon each of the counting steps.

4. The method of claim 2 wherein the size of the sampled middle portion comprises approximately one-third of the image line at the top of the image and comprises the entire image line at the bottom of the image.

5. The method of claim 1 wherein the second image includes only the samples.

6. The method of claim 1 comprising the further step of orienting the fisheye lens such that objects at the top of the image are farther away from the lens than objects at the bottom of the image.

7. A method of operating a video system, comprising the steps of:

dividing an image into a plurality of horizontal image lines; and

sampling a respective fraction of each of the horizontal image lines with a different respective sampling frequency, each sampling frequency being inversely related to a size of the sampled fraction, the size of the sampled fraction increasing with each horizontal image line in a progression from a first edge of the image to a second edge of the image.

8. The method of claim 7 wherein the image has been captured by use of a wide-angle lens.

9. The method of claim 7 wherein each said fraction comprises a respective middle portion of each said image line, and the size of the sampled fraction comprises approximately one-third of the image line at the first edge of the image and comprises the entire image line at the second edge of the image.

10. The method of claim 7 wherein the image comprises an analog image, the method comprising the further steps of:

converting the analog image into digital image data; and

converting the sampled digital image lines into a second analog image.

11. The method of claim 7 wherein the first edge of the image comprises a top of the image, and the second edge of the image comprises a bottom of the image, and wherein objects at the top of the image are farther away from the lens than objects at the bottom of the image.

12. The method of claim 7 comprising the further step of discarding portions of each horizontal line that are outside of the sampled fraction.

13. The method of claim 7 comprising the further steps of:

counting the horizontal image lines;

counting the number of pixels in each said image line; and

determining times at which to begin and end the sampling of each line, the determining being based upon each of the counting steps.

14. A method of operating a video system, comprising the steps of:

receiving a first analog image captured by use of a fisheye lens;

converting the analog image into digital image data;

dividing the image data into a plurality of image lines;

sampling a respective middle portion of each of the image lines with a different respective sampling frequency, each sampling frequency being inversely related to a fraction of the respective image line occupied by the middle portion, the fraction of the image line occupied by the middle portion increasing with each image line in a progression from a first edge of the image to a second edge of the image; and

converting the sampled digital image lines into a second analog image.

15. The method of claim 14 wherein each said sampling frequency is approximately between one and three times greater than a master clock frequency, and is dependent upon a distortion characteristic of the lens.

16. The method of claim 14 wherein the size of the sampled middle portion comprises approximately one-third of the image line at the first edge of the image and comprises the entire image line at the second edge of the image.

17. The method of claim 14 comprising the further step of storing the sampled digital image lines in a FIFO memory device.

18. The method of claim 14 wherein objects at the first edge of the image are farther away from the lens than objects at the second edge of the image.

19. The method of claim 14 comprising the further step of discarding portions of each horizontal line that are outside of the middle portion.

20. The method of claim 14 comprising the further steps of:

counting the image lines;

counting the number of pixels in each said image line; and

determining times at which to begin and end the sampling of each line, the determining being based upon each of the counting steps.