Method and apparatus for differential illumination image-capturing and defect handling

• US 6,498,867 B1
• Filed: 10/10/2000
• Issued: 12/24/2002
• Est. Priority Date: 10/08/1999
• Status: Expired due to Term

• Current Assignee: Kodak Alaris Inc (KPP (no. 2) Trustees Ltd.)
• Original Assignee: Applied Science Fiction, Inc.
• Inventors: Dundon, Thomas A., Potucek, Martin, Edgar, Albert D.
• Primary Examiner(s): ROGERS, SCOTT A
• Application Number:
  US09/686,719
• Time in Patent Office: 805 Days
• Field of Search: 382/274, 382/275, 382/112, 382/108, 382/145, 382/149, 382/219, 382/221, 382/141, 356/431, 356/430, 356/398, 356/237.1, 356/239.1, 356/239.7, 356/239.8, 356/237.2, 356/237.3, 356/237.4, 356/237.5, 350/463
• US Class Current: 382/274
• CPC Class Codes: H04N 1/00092 relating to the original or to the reproducing medium, e.g. imperfections or dirt detecting properties of a sheet H04N1/00681
• CPC Class Codes: H04N 1/00795 Reading arrangements details of scanning heads H04N1/024; scanning arrangements therefor H04N1/04
• CPC Class Codes: H04N 1/02815 Means for illuminating the original, not specific to a particular type of pick-up head
• CPC Class Codes: H04N 1/4097 Removing errors due external factors, e.g. dust, scratches

Abstract

An image processing system is disclosed. The system includes a first light source operable to illuminate an image plane in a first direction and a second light source operable to illuminate the image plane from a second direction. Also included is a sensing device operable to detect light from the first and second light source that interacted with the image plane. A processor operable to receive information from the sensing device and determine an image and image defects is coupled to the sensing device.

Claims

1. An imaging system comprising:

a first light source operable to illuminate an image plane in a first direction;

a second light source operable to illuminate the image plane from a second direction;

a third light source operable to illuminate the image plane;

a sensing device operable to detect light from the first light source, the second light source, and the third light source that interacted with and impinges the image plane; and

,

a processor operable to receive information from the sensing device and determine an image and image defects.

2. The system of claim 1, wherein the first and second light source are fluorescent light sources.

3. The system of claim 1, wherein one of the light sources is an infrared light source.

4. The system of claim 1, wherein one of the light sources is an ultraviolet light source.

5. The system of claim 1, wherein the first light source is set at a predetermined angle between 30 and 70 degrees from an image plane and the second light source is set at a predetermined angle between 110 and 150 degrees from an image plane.

6. The system of claim 1, wherein the image plane comprises a document.

7. The system of claim 1, wherein the image plane comprises a platen in the imaging system.

8. The system of claim 1, further comprising a transport mechanism and a controller.

9. The system of claim 8, wherein the transport mechanism is operable to move the sensing device across the image plane.

10. The system of claim 1, wherein the second light source comprises a reflective surface operable to receive light from the first light source and reflect the light to illuminate the image plane.

11. The system of claim 10, further comprising shutters placed between the first light source and the image plane and the second light source and the image plane, the shutters operable to control the illumination of the image plane.

12. The system of claim 1, wherein the light sources are set at a predetermined angle of substantially 120 degrees from each other.

13. The system of claim 12, wherein the first light source, the second light source and the third light source are associated with a drum scanner.

14. The system of claim 1, further comprising a fourth light source, the scanning device operable to detect light from the third light source and fourth light source which have been influenced by the image plane.

15. The system of claim 14, wherein the light sources are spaced substantially 90 degrees from each other.

16. The system of claim 1, wherein the first light source and second light source comprise a first mirror and a second mirror operable to focus light from a common source.

17. The system of claim 1, wherein the sensing device is placed behind the image plane and the image plane is substantially transparent.

18. The system of claim 1, wherein the processor operates to correct the image based on the image defects.

19. A method for obtaining an image and defect data comprising:

producing a first record image of a source document by illuminating a source document from a first direction, the illumination interacting with the source document;

producing a second record image of the source document by illuminating the source document from a second direction, the illumination interacting with the source document;

producing a third record image of the source document by illuminating the source document from a third direction; and

using the first record image, the second record image, and the third record image to reproduce an image of the source document and a defect map.

20. The method of claim 19, herein the step of using the first record further comprises the steps of:

detecting the illumination after interacting with the source document from the first direction and the second direction to form the first record and the second record; and

processing the records to form the image and the defect map.

21. The method of claim 19, wherein the steps of producing a first record image and producing a second record image further comprises:

using a first light source to illuminate the source document from the first direction; and

using a second light source to illuminate the source document from the second direction.

22. The method of claim 21, wherein the steps of using a first light source and using a second light source comprises using a fluorescent light source as a first light source and using a fluorescent light source as a second light source.

23. The method of claim 21, wherein the steps of using a first light source and using a second light source comprises using an infrared light source for at least one of the light sources.

24. The method of claim 19, wherein the steps of using a first light source and using a second light source further comprises using an ultraviolet light source for least one of the light sources.

25. The method of claim 19, wherein the steps of using a first light source and using a first light source further comprises using an infrared light source for at least one of the light sources further comprises:

setting the first light source at a predetermined angle between 30 and 70 degrees from an image plane; and

setting the second light source at a predetermined angle between 110 and 150 degrees from an image plane.

26. The method of claim 19, wherein the steps of producing a first record image and producing a second record image further comprises moving a sensing device over the document.

27. The method of claim 19, wherein the steps of producing a first record image and producing a second record image further comprises:

providing a first light source to illuminate the source document from a first direction; and

providing a reflective surface operable to receive light from the first light source and reflect the light to illuminate the document from a second direction.

28. The method of claim 19, wherein the steps of producing a first record image and producing a second record image further comprises:

using a common source of light to reflect light off a first mirror to illuminate the source document from a first direction; and

using the common source of light to reflect light off a second mirror to illuminate the source document from a second direction.

29. The method of claim 19, further comprising:

correcting the image using the defect map.

30. The method of claim 29, wherein a defect area is defined within the image;

and

the defect area is corrected by filling in the defect area with an average value obtained from the pixels surrounding but not including the defect area.

31. A method for obtaining an image and defect data comprising:

producing a first record image of a source document by illuminating a source document from a first direction, the illumination interacting with the source document;

producing a second record image of the source document by illuminating the source document from a second direction, the illumination interacting with the source document;

using the first record image and the second record image to reproduce an image of the source document and a defect map; and

correcting the image using the defect map, wherein the image is corrected by increasing an intensity of each image pixel by an amount proportional to the intensity of each defect pixel.

32. A scanner comprising:

a first light source operable to illuminate an image plane in a first direction;

a second light source operable to illuminate the image plane in a second direction;

a sensing device operable to detect light reflected by the image plane and to detect light from the second light source reflected from the image plane;

a processor operable to identify defect information using the difference in intensity of matching pixels in the first image record and the second image record;

wherein illumination from the first light source and the second light source are applied at separate times; and

a third light source operable to illuminate the image plane, the sensory device operable to detect light impinging the image plane from the first light source, the second light source and the third light source.

33. The scanner of claim 32, wherein the first and second light source are fluorescent light sources.

34. The scanner of claim 32, wherein one of the light sources is an ultraviolet light source.

35. The scanner of claim 32, wherein the first light source is set at a predetermined angle between 30 and 70 degrees from an image plane and the second light source is set at a predetermined angle between 110 and 150 degrees from the image plane.

36. The scanner of claim 32, further comprising a transport mechanism and a controller.

37. The scanner of claim 32, further comprising a transport mechanism operable to move the sensing device over the image plane.

38. The scanner of claim 32, wherein the second light source comprises a reflective surface operable to receive light from the first light source and reflect the light to illuminate the image plane.

39. The scanner of claim 32, wherein the light sources are set at a predetermined angle of substantially 120 degrees from each other.

40. The scanner of claim 32, wherein the first light source and second light source comprise a first mirror and a second mirror operable to focus light from a common source.

41. The scanner of claim 32, wherein the difference in intensity of matching pixels are used to form a defect map.

42. The scanner of claim 32, wherein the processor is also operable to correct the first image record using the defect information.

43. A scanner comprising:

a first light source operable to illuminate an image plane in a first direction;

a second light source operable to illuminate the image plane in a second direction;

a sensing device operable to detect light reflected by the image plane and to detect light from the second light source reflected from the image plane;

processor operable to identify defect information using the difference in intensity of matching pixels in the first image record and the second image record; and

wherein illumination from the first light source and the second light source are applied at separate times and the processor is also operable to correct the first image record by increasing an intensity of each first image record pixel by an amount proportional to the intensity of each matching defect pixel.

44. A method for acquiring a digital representation of an image plane comprising:

illuminating the image plane using a first light source from a first direction;

illuminating the image plane using a second light source from a second direction;

detecting the light interacting with the image plane from the first light source;

detecting the light interacting with the image plane from the second light sources;

creating a first image record from the detected interaction of the first light source with the image plane;

creating a second image record from the detected interaction of the second light source with the image plane;

processing the records to form an image and a defect map; and

correcting the image using the defect map, wherein the image is corrected by increasing an intensity of each pixel by an amount proportional to the intensity of each matching defect pixel.

45. The method of claim 44, wherein the steps of detecting the light interacting with the image plane comprises detecting light reflected from the image plane.

46. The method of claim 44, wherein the steps of detecting the light interacting with the image plane comprises, in part, detecting light transmitted through the image plane.

47. The method of claim 44, wherein a defect area is defined within the image;

and

the defect area is corrected by filling in the defect area with an average value obtained from the pixels surrounding, but not including, the defect area.

48. An imaging defect detection system comprising

a first light source operable to illuminate an image plane from a first direction;

a second light source operable to illuminate an image plane from a second direction;

a sensing system operable to detect light from the first light source and second light source that interacted with the image plane;

a processor operable to receive information from the sensing system and form a first image record from the light interacting with the image plane from the first light source and form a second image record from the second light source; and

,

wherein defects are located by comparing the first data record and the second data record and the processor is also operable to correct the first image record by increasing an intensity of each first image record pixel by an amount proportional to the intensity of each matching defect pixel.

49. The system of claim 48, wherein the image plane comprises a document.

50. The system of claim 48, wherein the image plane comprises a platen.

51. The system of claim 48, wherein the processor is also operable to correct the first image record using the location of the defects.

52. An imaging defect detection system comprising:

a first light source operable to illuminate an image plane from a first direction;

a second light source operable to illuminate an image plane from a second direction;

a third light source operable to illuminate the image plane;

a sensing system operable to detect light from the first light source, the second light source and the third light source that interacted with and;

impinges the image plane; and

a processor operable to receive information from the sensing system and form a first image record from the light interacting with the image plane from the first light source, form a second image record from the second light source, and form a third image record from the third light source, wherein defects are located by comparing the first data record, the second data record, and the third data record.

53. A method for determining a defect record of an image plane comprising:

obtaining a first image record based on light influenced by the image plane from a first light source;

obtaining a second image record based on light influenced by the image plane from a second light source;

obtaining a maximum pixel intensity record by comparing the first and second image records and selecting the highest pixel intensity value for a given pixel location;

obtaining a minimum pixel intensity record by comparing the first and second image records and selecting the lowest pixel intensity value for a given pixel location;

obtaining a difference record by subtracting the minimum pixel intensity record from the maximum pixel intensity value;

locating the center of a defect region by locating localized minimums in the difference record; and

determining defect boundaries based on the difference record.

54. The method of claim 53, further comprising:

determining upper and lower pixel intensity values from the difference record; and

labeling pixels as defective based on the upper and lower thresholds and the defect boundaries.

55. The system of claim 53, wherein the image plane comprises a document.

56. The system of claim 53, wherein the image plane comprises a platen.

57. The method of claim 53, further comprising:

correcting the image using the defect boundaries and difference record.

58. The method of claim 57, wherein the defect region is corrected by increasing an intensity of each first image record pixel in the defect region by an amount proportional to the intensity of each matching defect pixel.

59. A method for locating image defects comprising:

locating shadow pixels in a first image record;

locating shadow pixels in a second image record;

comparing the shadow pixel regions to form defect boundaries;

forming a defect map based on the defect boundaries; and

correcting the image using the defect map, wherein the first image record is corrected by increasing an intensity of each first image record pixel by an amount proportional to the intensity of each defect pixel.