Distortion free image capture system and method

• US 20020041383A1
• Filed: 08/15/2001
• Published: 04/11/2002
• Est. Priority Date: 08/16/2000
• Status: Active Grant

• Current Assignee: Clarence A. Lewis Jr, Richard Dale Lewis
• Original Assignee: Clarence A. Lewis Jr, Richard Dale Lewis
• Inventors: Lewis, Clarence A. Jr., Lewis, Richard Dale
• Granted Patent: US 6,816,625 B2
• Time in Patent Office: Days
• US Class Current: 358/1.9
• CPC Class Codes: H04N 23/81 for suppressing or minimising disturbance in the image signal generation
• CPC Class Codes: H04N 25/61 the noise originating only from the lens unit, e.g. flare, shading, vignetting or "cos4"

Abstract

A system and method for correcting distortions that occur in image capture systems is disclosed. The present invention in some preferred embodiments includes provisions to correct or change magnification differences for all causes including position errors in zoom lens positioning mechanisms as well as those caused by chromatic aberration, CCD alignment errors, lens distortion off center variations, pincushion/barrel lens distortion, magnification distortions, camera and lens misalignment errors, and lighting variations (including flash-to-flash illumination variations). A significant feature of the present invention in contrast with the prior art is that with the use of a movable calibration plate in the present invention it is possible to image capture both the calibration plate and the input object image in a single image capture, thus permitting simultaneous compensation for a variety of lighting and illumination variations not possible with the prior art.

Claims

1. An image capture system comprising:

(a) a geometric calibration plate;

(b) an illumination calibration plate;

(c) one or more lens(es) or optics;

(d) an imaging system;

(e) one or more imaging plane(s);

(f) an image processor;

wherein

said lens (es)/optics are used in conjunction with said imaging system to image said geometric and/or illumination calibration plate(s) to form an image correction database under control of said image processor;

said image correction database is used to create a distortion correction image under control of said image processor; and

said image processor permits application of said image correction database and/or said distortion correction image to an input object image to produce a distortion-free output image; and

said image processor simultaneously corrects for sources of geometric distortions, lighting variations, color variations, and magnification variances in said input object image.

2. The image capture system of claim 1 wherein said image processor is a personal computer.

3. The image capture system of claim 2 wherein said personal computer utilizes a Microsoft®

Windows™

operating environment.

4. The image capture system of claim 1 wherein said image processor communicates over the Internet to access a reference image and/or a reference image archive database.

5. The image capture system of claim 1 wherein said image processor first corrects for pixel geometric distortions and then assigns measured lighting values to said pixel positions.

6. The image capture system of claim 1 further comprising a camera digitization calibration system means.

7. The image capture system of claim 1 wherein said calibration plate(s) further comprise white and/or color chips to permit lighting values on said chips to correct for flash-to-flash variations in said object image illumination.

8. The image capture system of claim 1 wherein said calibration plate(s) are movable within the field of view of said input object image.

9. The image capture system of claim 1 wherein said calibration plate(s) are contained within the field of view of said input object image permitting said input object image to be corrected for flash-to-flash illumination variations.

10. The image capture system of claim 1 wherein said calibration plate(s) are contained at the edge of the field of view of said input object image permitting said input object image to be corrected for flash-to-flash illumination variations.

11. The image capture system of claim 1 wherein said image correction database further comprises

(1) means for setting an operating iris to full open;

(2) means for setting offsets;

(3) means for setting gains;

(4) means for setting the optimum iris value;

(5) means for setting said operating iris to said optimum value;

(6) means for setting offsets based on said optimum iris value; and

(7) means for setting gains based on said optimum iris value.

13. The image capture method of claim 12 wherein one or more steps are performed on a personal computer.

14. The image capture method of claim 13 wherein said personal computer utilizes a Microsoft®

Windows™

operating environment.

15. The image capture method of claim 12 wherein said distortion free output image is compared to a reference image and/or a reference image archive database that is accessed over the Internet.

16. The image capture method of claim 12 wherein said image processor first corrects for pixel geometric distortions and then assigns measured lighting values to said pixel positions.

17. The image capture method of claim 12 further comprising a calibrating camera digitization means process.

18. The image capture method of claim 12 further comprising viewing white and/or color chips in the field of view and using corrected lighting values on said chips to correct for flash-to-flash variations in said object image illumination.

19. The image capture method of claim 12 wherein said calibration plate is movable within the field of view of said input object image.

20. The image capture method of claim 12 wherein said calibration plate is contained within the field of view of said input object image permitting said input object image to be corrected for flash-to-flash illumination variations.

21. The image capture method of claim 12 wherein said calibration plate is contained at the edge of the field of view of said input object image permitting said input object image to be corrected for flash-to-flash illumination variations.

22. The image capture method of claim 12 wherein said image correction database generation step further comprises

(1) setting an operating iris to full open;

(2) setting offsets;

(3) setting gains;

(4) setting the optimum iris value;

(5) setting said operating iris to said optimum value;

(6) setting offsets based on said optimum iris value; and

(7) setting gains based on said optimum iris value.

24. The computer usable medium of claim 23 wherein said medium is compatible with a personal computer (PC).

25. The computer usable medium of claim 24 wherein said personal computer utilizes a Microsoft®

Windows™

operating environment.

26. The computer usable medium of claim 23 wherein said distortion free output image is compared to a reference image and/or a reference image archive database that is accessed over the Internet.

27. The computer usable medium of claim 23 wherein said computer program code means first corrects for pixel geometric distortions and then assigns measured lighting values to said pixel positions.

28. The computer usable medium of claim 23 further comprising computer program code means for calibrating camera digitization.

29. The computer usable medium of claim 23 further comprising computer program code means for viewing white and/or color chips in the field of view and using corrected lighting values on said chips to correct for flash-to-flash variations in said object image illumination.

30. The computer usable medium of claim 23 wherein said calibration plate is movable within the field of view of said input object image.

31. The computer usable medium of claim 23 wherein said calibration plate is contained within the field of view of said input object image permitting said input object image to be corrected for flash-to-flash illumination variations.

32. The computer usable medium of claim 23 wherein said calibration plate is contained at the edge of the field of view of said input object image permitting said input object image to be corrected for flash-to-flash illumination variations.

33. The computer usable medium of claim 23 wherein said image correction database further comprises

(1) computer program code means for setting an operating iris to full open;

(2) computer program code means for setting offsets;

(3) computer program code means for setting gains;

(4) computer program code means for setting the optimum iris value;

(5) computer program code means for setting said operating iris to said optimum value;

(6) computer program code means for setting offsets based on said optimum iris value; and

(7) computer program code means for setting gains based on said optimum iris value.

12. An image capture method comprising:

(1) image capturing a geometric calibration plate;

(2) image capturing an illumination calibration plate;

(3) generating an image correction database;

(4) generating an image correction image;

(5) capturing an image of an input object to be correctly imaged;

(6) applying said image correction database and/or said image correction to said input object image;

(7) generating a distortion free output image from the results of step (6).

wherein

said image capture method simultaneously corrects for sources of geometric distortions, lighting variations, color variations, and magnification variances in said object image.

23. A computer usable medium having computer-readable program code means providing image capture functionality, said computer-readable program means comprising:

(1) computer program code means for image capturing a geometric calibration plate;

(2) computer program code means for image capturing an illumination calibration plate;

(3) computer program code means for generating an image correction database;

(4) computer program code means for generating an image correction image;

(5) computer program code means for capturing an image of an input object to be correctly imaged;

(6) computer program code means for applying said image correction database and/or said image correction to said input object image; and

(7) computer program code means for generating a distortion free output image from the results of said means (6);

wherein

said computer program code means for image capturing simultaneously corrects for sources of geometric distortions, lighting variations, color variations, and magnification variances in said object image.