Charactering and calibrating an image capture device

• US 6,654,493 B1
• Filed: 11/12/1999
• Issued: 11/25/2003
• Est. Priority Date: 11/13/1998
• Status: Expired due to Term

• Current Assignee: RPX Corporation
• Original Assignee: LightSurf Technologies, Inc. (VeriSign, Inc.)
• Inventors: Strother, Thomas L., Engeldrum, Peter G., Hilliard, William J.
• Primary Examiner(s): Wu, Jingge
• Application Number:
  US09/440,013
• Time in Patent Office: 1,474 Days
• Field of Search: 382/162, 382/167, 358/518-540, 345/597-628
• US Class Current: 382/167
• CPC Class Codes: G09G 2320/0693 Calibration of display systems
• CPC Class Codes: G09G 5/00 Control arrangements or circuits for visual indicators common to cathode-ray tube indicators and other visual indicators image data processing or generation, in general G06T
• CPC Class Codes: H04N 17/002 for television cameras
• CPC Class Codes: H04N 17/02 for colour television signals

Abstract

A method and system for calibrating and characterizing an image capture device is disclosed. Using a calibrated display of known colorimetric properties, a feedback loop method and system is disclosed such that the image capture device capture device can be calibrated.

Claims

1. A method for calibrating and characterizing an image capture device, comprising the steps of:

i) calibrating a display device to generate a calibrated display;

ii) displaying at least one reference image on the calibrated display to generate a calibrated reference image with known calorimetric properties, said at least one reference image simulating the average correlated color temperature of a light source of images to be subsequently captured;

iii) capturing at least one image from an image capture device to be calibrated, to generate a captured image;

iv) comparing the captured image with the known calorimetric properties of the calibrated reference image;

v) computing a relationship between the captured image and the known calorimetric properties of calibrated reference image; and

vi) writing a profile describing colorimetric characteristics of the image capture device according to the relationship such that the profile can be used to calibrate the image capture device.

2. A method for enhancing captured images, comprising:

operating an image capture device to form a captured image of a first image displayed on a calibrated display device having known display properties; and

determining differences between the first image and the captured image for capturing subsequent images with the image capture device in accordance with the difference;

wherein operating an image capture device to form a captured image of a first image displayed on a calibrated display device comprises;

operating an image capture device to form a captured image of a first image simulating the light source of the images subsequently captured with the image capture device; and

wherein capturing a first image simulating the light source of the images to be subsequently captured with the image capture device comprises;

capturing at least one reference image simulating the average correlated color temperature of the light source of the images subsequently captured with the image capture device.

3. The method of claim 2, wherein determining differences between the first image and the captured image comprises:

determining differences between the first image and the captured image for adjusting the image capture device to capture subsequent images in accordance with the differences.

4. The method of claim 2, wherein determining differences between the first image and the captured image comprises:

determining differences between the first image and the captured images for adjusting images subsequently captured with the image capture device in accordance with the differences.

5. The method of claim 2, wherein operating an image capture device to form a captured image of a first image displayed on a calibrated display device comprises:

operating an image capture device to form a captured image of a first image displayed on a display device calibrated to display accurate color, to display accurate spectral radiance, or to exhibit known colorimetric characteristics.

6. The method of claim 5, wherein operating an image capture device to form a captured image of a first image displayed on a calibrated display device comprises:

operating an image capture device to form a captured image of a first image displayed on a calibrated display device displaying one or more primary colors.

7. The method of claim 2, wherein operating an image capture device to form a captured image of a first image displayed on a calibrated display device further comprises:

generating the first image for display on the calibrated display device.

8. The method of claim 7, wherein generating the first image for display on the calibrated display device comprises:

generating a series of first images for display on the calibrated display device.

9. The method of claim 8, wherein generating a series of images for display on the calibrated display device further comprises:

writing a first image profile to be stored in memory for subsequent display of the first images.

10. The method of claim 2, wherein operating an image capture device to form a captured image of a first image displayed on a calibrated display device further comprises:

operating an image capture device to form a captured image of a first image comprising the primary colors of red, green, and blue.

11. The method of claims 2, wherein operating an image capture device to form a captured image of a first image displayed on a calibrated display device comprises:

operating an image capture device to form a captured image of a first image comprising redundant colors, redundant colored areas, or comprising a color test pattern.

12. The method of claim 2, wherein operating an image capture device to form a captured image of a first image displayed on a calibrated display device comprises:

operating an image capture device to form captured images of a series of first images displayed on a calibrated display device.

13. The method of claim 12, wherein operating an image capture device to form captured images of a series of first images displayed on a calibrated display device comprises:

operating an image capture device to form captured images of a series of first images comprising the primary colors of red, green, and blue.

14. The method of claims 12, wherein capturing a series of reference images displayed on the calibrated display device comprises:

capturing a series of reference images comprising redundant colors, redundant colored areas, or color test patterns.

15. The method of claim 2, wherein operating an image capture device to form a captured image of a first image displayed on a calibrated display device comprises:

operating an image capture device to form a captured image of a first image simulating properties of the source of the images subsequently captured with the image capture device.

16. The method of claim 2, wherein operating an image capture device to form a captured image of a first image displayed on a calibrated display device comprises:

operating an image capture device to form a captured image of a first image comprising regions of the image capture device color space selected in accordance with the nonlinearity of the image capture device.

17. The method of claim 12, wherein operating an image capture device to form captured images of a series of first images displayed on a calibrated display device comprises:

operating an image capture device to form captured images of a series of first images comprising test patterns having varied spatial locations.

18. The method of claim 17, wherein determining differences comprises:

determining differences between each first image and the captured image associated with each such first image.

19. The method of claim 17, wherein determining differences further comprises:

averaging the captured images.

20. The method of claim 12, wherein operating an image capture device to form captured images of a series of first images displayed on a calibrated display device comprises:

operating an image capture device to form captured images of a series of first images displayed on a calibrated display device, each such first image consisting of one color.

21. The method of claim 2, wherein determining differences between the first image and the captured image further comprises:

creating a profile for the image capture device in accordance with the differences.

22. The method of claim 21, wherein creating a profile for the image capture device in accordance with the differences comprises:

creating an ICC profile for the image capture device.

23. The method of claim 21, wherein creating a profile for the image capture device in accordance with the differences comprises:

creating a profile for the image capture device to capture subsequent images in accordance with the profile.

24. The method of claim 23, wherein creating a profile for the image capture device to capture subsequent images in accordance with the profile comprises:

creating a profile for the image capture device to adjust the image capture device to capture subsequent images in accordance with the profile.

25. The method of claim 23, creating a profile for the image capture device to capture subsequent images in accordance with the profile comprises:

creating a profile for the image capture device to adjust images subsequently captured with the image capture device in accordance with the profile.

26. The method of claim 2, wherein determining differences between the first image and the captured image comprises:

determining differences between any of the radiance, reflectance, irradiance, or colors of the first image and the captured image.

27. A method for operating a digital image capture device, comprising:

operating a digital image capture device to form a captured image of a first image displayed on a display monitor calibrated to display the first image with known color characteristics, including providing a Central Processing Unit connected to the display monitor to display a first image on the display monitor calibrated to display the first image with known color characteristics; and

determining differences between the first image and the captured image for capturing subsequent images with the digital image capture device in accordance with the differences;

wherein operating a digital image capture device to form a captured image of a first image on a display monitor calibrated to display the first image with known color characteristics comprises;

operating a digital image capture device to form a captured image of a first image simulating the average correlated color temperature of the light source of the images subsequently captured with the image capture device.

28. The method of claim 27, wherein providing a Central Processing Unit connected to the display monitor display a first image on the display monitor with known color characteristics further comprises:

providing a Central Processing Unit connected to the display monitor to generate a first image for display on the display monitor calibrated with known color characteristics.

29. The method of claim 28, wherein providing a Central Processing Unit connected to the display monitor to generate a first image for display on the display monitor with known color characteristics comprises:

providing a Central Processing Unit connected to a display monitor to generate a first image comprising the primary colors of red, green, and blue for display on the display monitor with known color characteristics.

30. The method of claim 28, wherein providing a Central Processing Unit connected to the display monitor to generate a first image for display on the display monitor with known color characteristics comprises:

providing a Central Processing Unit connected to a display monitor to generate a first image comprising redundant colors, redundant color areas, or a color test pattern.

31. The method of claim 27, wherein operating a digital image capture device to form a captured image of a first image displayed on a display monitor comprises:

operating a digital image capture device to form captured images of a series of first images displayed on a display monitor.

32. The method of claim 31, wherein operating a digital image capture device to form captured images of a series of first images displayed on a display monitor further comprises:

providing a Central Processing Unit connected to the display monitor to generate a series of first images for display on the display monitor.

33. The method of claim 32, wherein providing a Central Processing Unit connected to the display monitor to generate a series of first images comprises:

providing a Central Processing Unit connected to the display monitor to generate a series of first images comprising the primary colors of red, green, and blue.

34. The method of claim 32, wherein providing a Central Processing Unit connected to the display monitor to generate a series of reference images comprises:

providing a Central Processing Unit connected to the display monitor to generate a series of reference images comprising redundant colors, redundant colored areas, or color test patterns.

35. The method of claim 27, wherein operating a digital image capture device to form a captured image of a first image displayed on a calibrated display monitor comprises:

operating a digital camera to form a captured image of a first image displayed on a calibrated display monitor.

36. The method of claim 35, wherein operating a digital camera to form a captured image of a first image displayed on a calibrated display monitor further comprises:

disabling any image compensation features of the digital camera prior to operating the digital camera to form a captured image of a first image displayed on a calibrated display monitor.

37. The method of claim 27, wherein operating a digital image capture device to form a captured image of a first image on a display monitor calibrated to display the first image with known color characteristics comprises:

operating a scanner to form a captured image of a first image displayed on a display monitor calibrated to display the first image with known color characteristics.

38. The method of claim 27, wherein operating a digital image capture device to form a captured image of a first image on a display monitor calibrated to display the first image with known color characteristics comprises:

operating a digital image capture device to form a captured image of a first image comprising regions of the image capture device color space selected in accordance with the nonlinearity of the digital image capture device.

39. The method of claim 32, wherein operating a digital image capture device to form captured images of a series of first images displayed on a display monitor comprises:

operating a digital image capture device to form captured images of a series of first images comprising test patterns having varied spatial locations.

40. The method of claim 39, wherein determining differences comprises:

determining differences between each first image and the captured image associated with each such first image.

41. The method of claim 40, wherein determining differences further comprises:

averaging the captured images.

42. The method of claim 32, wherein operating a digital image capture device to form captured images of a series of first images displayed on a display monitor comprises:

operating a digital image capture device to form captured images of a series of first images displayed on a display monitor, each such first image consisting of one color.