Apparatus and method for producing images without distortion and lateral color aberration

• US 6,747,702 B1
• Filed: 12/23/1998
• Issued: 06/08/2004
• Est. Priority Date: 12/23/1998
• Status: Expired due to Term

• Current Assignee: Monument Peak Ventures, LLC (Dominion Harbor Enterprises, LLC)
• Original Assignee: Eastman Kodak Company
• Inventors: Harrigan, Michael E.
• Primary Examiner(s): Garber, Wendy R.
• Assistant Examiner(s): Rosendale, Matthew L
• Application Number:
  US09/220,162
• Time in Patent Office: 1,994 Days
• Field of Search: 348/241, 348/335, 348/207.1, 348/207.11
• US Class Current: 348/335
• CPC Class Codes: H04N 23/81 for suppressing or minimising disturbance in the image signal generation

Abstract

According to one aspect of the invention, an apparatus for forming distortion free images comprises: (i) a rotationally symmetric lens system capable of forming a distorted image and of introducing lateral color aberration; (ii) a photosensitive image capture medium capable of capturing the distorted image created by the lens system; (iii) an image storage medium storing the distorted image captured by the image capture medium; (iv) an image buffer medium (area) for holding at least one distorted image stored by the image storage medium; and (v) an image processing unit correcting the distorted image and creating an undistorted image. The image processing unit has information describing distortion and lateral color aberration characteristics of the lens system. The image processing unit calculates, for at most one quadrant of the image, given any ideal radial position of a pixel, the actual radial position of the distorted data pixel from which to retrieve the data. Then the image processing unit moves the data corresponding to the radial value of the pixel with the distorted data to its undistorted pixel location in each quadrant of the image, thereby building a corrected image. The corrected image is stored in the image buffer medium; and then moved from the buffer to the image storage medium.

Claims

1. An apparatus for producing a distortion-free image, said apparatus comprising:

a rotationally symmetric lens system capable of forming a distorted image and of introducing lateral color aberration;

a photosensitive image capture medium capable of capturing said distorted image created by said lens system;

an image storage medium storing data representing said distorted image captured by said image capture medium;

an image buffer for holding data representing distortion free image;

an image processing unit transposing said data representing said distorted image to a set of data that represents a distortion-free image;

said image processing unit having information describing distortion and lateral color aberration characteristics of said lens system, and said image processing unit being adapted to

calculate for at most one quadrant of the image, given any ideal radial position of a pixel, the actual radial position of the distorted data pixel from which to retrieve the data,

move the data corresponding to the radial value of the pixel with the distorted data to its undistorted pixel location in each image quadrant, thereby building a distortion-free image;

store the data representing said distortion-free image in said image buffer medium; and

move said data representing said distortion-free image from said buffer to said image storage medium.

2. An apparatus according to claim 1, wherein said apparatus overwrites said distorted image data in said image storage medium by said data representing said distortion-free image.

3. An apparatus according to claim 1, wherein said image capture medium is a CCD array.

4. An apparatus according to claim 1, wherein said image capture medium is a CMOS array.

5. An apparatus according to claim 1, wherein said apparatus is a photographic camera and said image storage medium is part of said camera.

6. An apparatus according to claim 1, wherein said apparatus is a photographic camera and said image processing unit is part of said camera.

7. An apparatus according to claim 1, wherein said apparatus includes:

a photographic camera, and a separate computer containing said image processing unit.

8. An apparatus according to claim 7, wherein image storage medium is part of said camera.

9. An apparatus comprising:

a lens with a predetermined full field angle of more than 50 degrees, said lens having at least ±

6% distortion;

a photosensitive medium receiving a distorted image created by said lens, said photosensitive medium being of a size such that at said full field angle the distorted image just fits within said photosensitive medium and the paraxial image corresponding to this field angle does not touch the sides of said photosensitive medium; and

an image processing unit processing said data representing said distorted image transposing said data to represent an undistorted image, wherein said distorted image has a corresponding distortion-free image whose data point locations are characterized by r(λ

) and the location of the corresponding data point of said distorted image is characterized by a radial distance R(λ

) such that R(λ

) is determined from r by the following equation

10. An apparatus according to claim 9, wherein said undistorted image is 94% to 106% of the size of said photosensitive medium.

11. An apparatus according to claim 9, wherein said photosensitive medium is a sensor array with a plurality of pixels and said undistorted image is made of a number of data points such that said number of data points is 94% to 106% of pixels of said photosensitive medium.

12. An apparatus according to claim 9, further comprising an image processing unit adapted to move the data corresponding to data point locations R(λ

) to data point locations r(λ

), thereby creating an image data set representing said distortion-free image.

13. An apparatus comprising:

a camera capturing images with at least 6% distortion, said camera containing a file with at least one of the following parameters;

coefficients describing distortion, lens scale factor, full field angle and lens focal length; and

a kiosk comprising a computer operatively connected to said camera, wherein said kiosk receives (i) said distorted image data corresponding to said captured images and (ii) said file and,

utilizing said parameters, determines positions of data points that correspond to a predetermined ideal location; and

moves said data to said ideal location, thereby creating a distortion-free image, wherein said distorted image data has a corresponding distortion-free image whose data point locations are characterized by r(λ

) and the location of the corresponding data point of said distorted image is characterized by a radial distance R(λ

) such that R(λ

) is determined from r by the following equation;

14. A method of producing a distortion-free image, said method comprising the following steps:

(i) producing an image with at lest 6% distortion;

(ii) finding, for a predetermined image location of said distortion-free image, a corresponding location in said distorted image;

(iii) copying data located at said corresponding location of said distorted image into said predetermined image location and copying corresponding data from three other quadrants of said distorted image into their corresponding locations in said distortion-free image, wherein said corresponding image locations are characterized by the same radial distance from the center of the distortion-free image.

15. A method of producing a distortion-free image according to claim 14 wherein said method further includes scaling said distortion-free image to exactly fit a sensor array.