WO2001028225A1

WO2001028225A1 - Scanner and method

Info

Publication number: WO2001028225A1
Application number: PCT/US2000/011611
Authority: WO
Inventors: Thomas A. Dundon; Gordon D. Ford
Original assignee: Applied Science Fiction, Inc.
Priority date: 1999-10-08
Filing date: 2000-06-08
Publication date: 2001-04-19
Also published as: AU7699200A

Abstract

One aspect of the invention is a scanner operable to scan a tangible medium having an image thereon. The scanner has a first light source and a second light source wherein the second light source is an infrared light source. The scanner further comprises sensing circuitry operable to produce a first electric signal responsive to the intensity of light reflected from at least one pixel area of the tangible medium in response to light produced by the first light source and to generate a first data value in response to the first electric signal. The sensing circuitry is further operable to produce a second electric signal responsive to the intensity of light reflected from the at least one pixel area in response to the light produced by the second light source and to generate a second data value responsive to the second electric signal. The second data value may be used to predict the existence of a defect in a digital representation of the image.

Description

SCANNER AND METHOD

TECHNICAL FIELD OF THE INVENTION

This invention relates generally to image processing and more particularly, to a scanner and method useful for predicting the existence of defects in a scanned image.

BACKGROUND OF THE INVENTION

Tangible images, such as photographic prints, may have surface defects such as scratches, fingerprints, or dust particles. Such defects may often undesirably degrade a photographic image. In addition, imperfections in an optical system used to electronically capture an image may lead to further introduction of defects that distort and obscure the image.

In the field of image processing, digital images derived from photographic images and other tangible images using a scanner most often include the defects present in the underlying photographic print or other tangible image. Because digital images are subject to mathematical manipulation, if image defects may be identified and distinguished from image detail, then those defects can be removed, either partially or completely. Accordingly, there is a need for a system that allows defect data to be captured but may be used to reduce or remove defects from an image obtained using a scanner .

SUMMARY OF THE INVENTION One aspect of the invention is a scanner operable to scan a tangible medium having an image thereon. The scanner has a first light source and a second light source wherein the second light source is an infrared light source. The scanner further comprises sensing circuitry operable to produce a first electric signal responsive to the intensity of light reflected from at least one pixel area of the tangible medium in response to light produced by the first light source and to generate a first data value in response to the first electric signal. The sensing circuitry is further operable to produce a second electric signal responsive to the intensity of light reflected from the at least one pixel area in response to the light produced by the second light source and to generate a second data value responsive to the second electric signal. The second data value may be used to predict the existence of a defect in a digital representation of the image.

The invention has several important technical advantages. Various embodiments of the invention may have none, one, some, or all of these advantages without departing from the scope of the invention. The invention allows the creation of data representative of defects in an image and/or in optical scanning equipment used to capture the image from a tangible medium. The invention allows the defect information to be captured using a number of hardware configurations. BRIEF DESCRIPTION OF THE DRAWINGS For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawing in which: FIGURE 1 illustrates a block diagram of a scanner constructed in accordance with the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

The preferred embodiment of the present invention and its advantages are best understood by referring to FIGURE 1 of the drawing, like numerals being used for like and corresponding parts of the drawing.

FIGURE 1 illustrates a scanner 10 constructed in accordance with the teachings of the invention. Scanner 10 comprises first light source 14, second light source 16, optics 18, sensing circuitry 20, document or sensor transport mechanism 24 and controller 26. Some of these elements could be omitted or other elements added without departing from the scope of the invention. The functions of various elements could be combined with the functions of other elements and be performed by the same element without departing from the scope of the invention.

Scanner 10 may be used to scan a tangible medium, such as document 12, having an image thereon. In this embodiment, document 12 may be scanned by reflecting light off of its surface and sensing the reflected light using sensing circuitry 20. Document 12 may comprise any tangible medium, such as a photograph, without departing from the scope of the invention. Document 12 is illuminated by first light source 14 and second light source 16. In this embodiment, first light source 14 comprises a visible light source operable to produce visible light that may be reflected from the surface, in whole or in part, from document 12. First light source 14 is used to produce light that may be used to capture a digital representation of the image from document 12. Such light may be used to create a monochromatic digital image or a multi -channel color digital image without departing from the scope of the invention.

Second light source 16 comprises an infrared light source. Second light source 16 may be used to create infrared light that may be used to capture defect information concerning the digital image captured by scanner 10. The term, "infrared light source," broadly includes any combination of elements capable of producing infrared light. For example, light source 16 may be a visible light source whose light output is passed through an infrared filter.

Second light source 16 may comprise the same light source as first light source 14. In such a case, the light source may have a removable (or movable) infrared filter that is in place when the light source is used for scanning the defect channel and acting as an infrared light source but the filter is not in place when the light source is being used to capture a digital representation of the image of document 12. Thus, first light source 14 and second light source 16 may be the same source of light in combination with a filter used part of the time. The positioning of first light source 14 and second light source 16 in FIGURE 1 are for illustration only and any positioning of the various light sources may be used without departing from the scope of the invention. Scanner 10 further comprises optics 18 and sensing circuitry 20. Optics 18 comprises any series of mirrors and lenses that may be used to focus light reflected from document 12 onto the sensor portion of sensing circuitry 20. Alternatively, optics 18 may be omitted if sensing circuitry 20 is capable of receiving light reflected from document 12 without the use of optics 18.

Sensing circuitry 20 comprises a sensor operable to convert light reflected from document 12 into an electric signal. Sensing circuitry 20 further comprises analog to digital conversion circuitry operable to convert an electric signal into a digital value.

Sensing circuitry 20 can use any type of electric sensor such as a charge coupled device. Although this embodiment employs a charge coupled device sensor for sensing circuitry 20, other types of sensors such as CMOS sensors or contact sensors may also be used. The charge coupled device may be any number of pixels long and any number of pixels wide without departing from the scope of the invention. In addition, multiple sensors may be included in sensing circuitry 20 without departing from the scope of the invention. Sensing circuitry 20 may be stationary or may move in a first direction, a first and second direction, or in more than two directions without departing from the scope of the invention. In some embodiments, sensing circuitry 20 may move in both the x and y directions while in other scanners 10 sensing circuitry 20 may move in only the x direction. In other scanners 10, sensing circuitry 20 may be stationary and operable to capture the image information from the entire document 12 without document 12 or sensing circuitry 20 moving. In addition, sensing circuitry 20 may be stationary and document 12 may be moved to complete a scan without departing from the scope of the invention.

Sensing circuitry 20 may comprise a plurality of charge coupled device sensors associated with filters. In one embodiment, sensing circuitry 20 comprises a charge coupled device with three lines of pixel sensors (each line including a plurality of pixels) extending the entire width of document 12. Such a charge coupled device may have a red filter over one line of the device, a green filter over a second line, and a blue filter over a third line. Such a sensor may be used to capture the red, green and blue channels of a color digital image. Such a device may have a fourth line of sensors associated with an infrared filter through which light passes for use in capturing defect information associated with the optical circuitry of scanner 10 and/or defects in the image of document 12. Alternatively, one or more of the other three lines of sensors may be used to sense infrared light produced by a second light source 16 during the capture of the defect channel. Any size sensor of any kind in association with any number of filters may be used without departing from the scope of the invention. For example, single sensors with movable filters applying different color filters during multiple scans of the same pixel may be used.

If sensing circuitry 20 comprises a charge coupled device sensor having multiple lines with each line associated with a different color filter, then the defect channel may be scanned at a faster rate. Such red, green and blue filters will typically allow infrared radiation to pass through them. Accordingly, each line of the sensor may be used to detect infrared light produced by second light source 16 during the scan of the defect data for document 12. Thus, the second scan in either the forward or reverse direction may occur faster than the rate of a first scan if multiple lines of sensors are used to capture the defect data.

Controller 26 may be used to turn first light source 14 and second light source 16 on and off as well as to move document 12 relative to sensing circuitry 20. Document 12, optics 18, and/or sensing circuitry 20 may be moved relative to any of the other elements without departing from the scope of the invention. Controller 26 may control document or sensor transport mechanism 24 to affect movement of the proper element or elements.

Controller 26 comprises any type of circuitry operable to control first light source 14, second light source 16, sensing circuitry 20 and/or document or sensor transport mechanism 24. Controller 26 may be a microprocessor, microcontroller, application specific integrated circuit, gate array, state machine, or any other type of digital or fuzzy logic circuit. The data obtained for each pixel for sensing circuitry 20 may be stored in a memory associated with sensing circuitry 20 and/or controller 26.

Optics 18 and/or sensing circuitry 20 may be moved using any type of devices such as stepper motors, servo motors, a rack and pinion, gears, cams, levers, etc. Document 12 may be moved using any type of mechanism such as, for example, a movable platform, rollers, a drum, air, a vacuum, a tractor feed, or any other type of mechanism used to move a document in devices such as scanners, copy machines, fax machines, etc. Scanner 10 may be operated in a number of ways to obtain a digital image having one or more channels and a defect channel associated with the digital image. In one embodiment, the digital image is illuminated by light source 14 and the image is scanned during a first pass. After the image has been scanned from document 12 to create the one or more channels of the digital representation of the image on document 12 (the digital image) , then there are several options for obtaining the defect information. First, scanner 10 could turn off first light source 14 and turn on second light source 16 and scan the image in the opposite direction. Alternatively, scanner 10 could return to the position in which the scanning of the multi -channel digital image was begun and perform a second pass over document 12 in the same direction as the first pass to obtain the defect information. Again, first light source 14 would be turned off while second light source 16 was illuminated during the second pass. Again, as described above, the same effect may be achieved by using the same light source with an infrared filter present during the second pass but not present during the first pass. In addition, the order of the passes is insignificant. The defect information could be obtained during the first pass without departing from the scope of the invention.

Alternatively, the defect channel and digital image channels may be obtained during a single pass over document 12. In such an embodiment, first light source 14 may be illuminated to obtain information from one or more pixel areas of document 12. After that information has been obtained, first light source 14 may be turned off and second light source 16 may be turned on (or the infrared filter moved in place) . When second light source 16 has been turned on, then the defect data may be obtained. After both the information for the channels of the digital image and the defect channel have been obtained, scanner 10 may then move to the next position for obtaining the next set of data for the multiple channels of the digital image and the defect channel.

In another embodiment, some information for the digital image would be obtained over an area that involves movement of the sensing circuitry or optics 18 relative to document 12 (including movement of document 12 and no movement by optics 18 or sensing circuitry 20) . The first light source 14 would be illuminated for this scanning. Then, some defect information may be obtained with second light source 16 illuminated and first light source 14 not illuminated. Such defect information could be obtained for the same area or a different area as compared to the scan of the image information. For example, the first pass over a line of pixels, or multiple lines of pixels of an image might pick up the image information and a scan in the opposite direction might pick up the defect information. Alternatively, the second pass over the line or group of lines could be in the same direction. Movement in any direction is possible without departing from the scope of the invention.

All of the methods of operation described above may be used whether the document 12 is moved, the optics 18 are moved and/or the sensing circuitry 20 is moved relative to the other elements. Alternatively, if one can employ multiple sensors for sensing circuitry 20, with one sensor associated with first light source 14 and one sensor associated with light source 16, then first light source 14 and second light source 16 may be illuminated for the entire scan. Such an embodiment desirably would employ sensors and light sources positioned such that the light from light source 14 did not interfere with the light from second light source 16 that is received by the sensor used to create the defect channel. Scanner 10 may scan the entire surface of document 12, or a smaller or larger area without departing from the scope of the invention.

While the invention has been particularly shown and described by the foregoing detailed description, it will be understood by those skilled in the art that various other changes in form and detail may be made without departing from the spirit and scope of the invention.

Claims

WHAT IS CLAIMED IS:

1. A scanner operable to scan a tangible medium having an image thereon, comprising: a first light source operable to illuminate at least a portion of the tangible medium; a second light source operable to illuminate the at least a portion of the tangible medium wherein the second light source comprises an infrared light source; and sensing circuitry operable to produce a first electric signal responsive to the intensity of light reflected from at least one pixel area of the tangible medium in response to light produced by the first light source, the sensor further operable to generate a first data value responsive to the first electric signal, operable to produce a second electric signal responsive to the intensity of light reflected from the at least one pixel area of the tangible medium in response to light produced by the second light source, the sensor further operable to generate a second data value responsive to the second electric signal, and wherein the second data value may be used to predict the existence of a defect in a digital representation of the image.

2. The scanner of Claim 1, wherein the sensing circuitry comprises a single sensor, operable to generate the first electric signal when the first light source is on and the second light source is off and to generate the second electric signal when the second light source is on and the first light source is off.

3. The scanner of Claim 1, wherein the sensing circuitry further comprises: a first sensor operable to generate the first electric signal when the first light source is on and the second light source is off; and a second sensor operable to generate the second electric signal when the second light source is on and the first light source is off.

4. The scanner of Claim 1, further comprising: a carriage coupled to the sensing circuitry and operable to move the sensing circuitry relative to the tangible medium.

5. The scanner of Claim 4, wherein the carriage moves in a first direction and in a second direction and wherein the first light source is on and second light source is off for at least part of the time that the carriage moves in the first direction and wherein the first light source is off and second light source is on for at least part of the time that the carriage moves in the second direction.

6. The scanner of Claim 5, wherein the first direction is opposite to the second direction.

7. The scanner of Claim 4, wherein the first data value and the second date value are determined for the at least one pixel area without moving the carriage.

8. The scanner of Claim 1, further comprising: a tangible medium transporter operable to move the tangible medium relative to the sensor.

9. The scanner of Claim 8, further comprising: a carriage coupled to the sensing circuitry and operable to move the sensing circuitry relative to the tangible medium.

10. The scanner of Claim 9, wherein the carriage moves in a first direction and in a second direction and wherein the first light source is on and second light source is off for at least part of the time that the carriage moves in the first direction and wherein the first light source is off and second light source is on for at least part of the time that the carriage moves in the second direction.

11. The scanner of Claim 8, wherein the tangible medium transporter moves in a first direction and in a second direction and wherein the first light source is on and second light source is off for at least part of the time that the tangible medium transporter moves in the first direction and wherein the first light source is off and second light source is on for at least part of the time that the tangible medium transporter moves in the second direction.

12. The scanner of Claim 8, wherein the first data value and the second data value are determined for the at least one pixel without moving the tangible medium transporter.

13. The scanner of Claim 4, wherein the carriage moves in a first direction and in a second direction, wherein the carriage makes at least a first pass and a second pass over substantially the same area of the tangible medium while moving in the first direction, and wherein the first light source is on and second light source is off for at least part of the first pass and wherein the first light source is off and second light source is on for at least part of the second pass.

14. The scanner of Claim 8, wherein the tangible medium transporter moves in a first direction and in a second direction, wherein the tangible medium transporter makes at least a first pass and a second pass such that the sensing circuitry senses light reflected from substantially the same area of the tangible medium while moving in the first direction, and wherein the first light source is on and second light source is off for at least part of the first pass and wherein the first light source is off and second light source is on for at least part of the second pass .

15. The scanner of Claim 1, wherein the infrared light source comprises an electric device producing infrared light.

16. The scanner of Claim 1, wherein the infrared light source comprises a visible light source in combination with an infrared filter.

17. A method for predicting the existence of a defect in a digital representation of an image on a tangible medium, comprising: illuminating at least a portion of the tangible medium with a first light source; generating a first electric signal responsive to the intensity of light reflected from at least one pixel area of the tangible medium in response to light produced by the first light source; generating a first data value responsive to the first electric signal; illuminating at least a portion of the tangible medium with a second light source, wherein the second light source comprises an infrared light source ; generating a second electric signal responsive to the intensity of light reflected from the at least one pixel area of the tangible medium in response to light produced by the second light source; generating a second data value responsive to the second electric signal; and predicting the existence of a defect in the digital representation of an image in response to the second data value .

18. The method of Claim 17, wherein the first electric signal is generated when the first light source is on and the second light source is off and wherein the second electric signal is generated when the second light source is on and the first light source is off.

19. The method of Claim 17, wherein the first electric signal and second electric signal are generated by sensing circuitry, the method further comprising moving the sensing circuitry relative to the tangible medium.

20. The method of Claim 19, wherein the sensing circuitry moves in a first direction and in a second direction and wherein the first light source is on and second light source is off for at least part of the time that the sensing circuitry moves in the first direction and wherein the first light source is off and second light source is on for at least part of the time that the sensing circuitry moves in the second direction.

21. The method of Claim 19, wherein the first data value and the second date value are determined for the at least one pixel area without moving the sensing circuitry

22. The method of Claim 17, further comprising: moving the tangible medium relative to sensing circuitry used to generated the first electric signal and second electric signal .

23. The method of Claim 22, further comprising: moving the sensing circuitry relative to the tangible medium.

24. The method of Claim 23, wherein the sensing circuitry moves in a first direction and in a second direction and wherein the first light source is on and second light source is off for at least part of the time that the sensing circuitry moves in the first direction and wherein the first light source is off and second light source is on for at least part of the time that the sensing circuitry moves in the second direction.

25. The method of Claim 22, wherein the tangible medium moves in a first direction and in a second direction and wherein the first light source is on and second light source is off for at least part of the time that the tangible medium moves in the first direction and wherein the first light source is off and second light source is on for at least part of the time that the tangible medium moves in the second direction.

26. The method of Claim 22, wherein the first data value and the second date value are determined for the at least one pixel without moving the tangible medium.

27. The method of Claim 19, wherein the sensing circuitry moves in a first direction and in a second direction, wherein the sensing circuitry makes at least a first pass and a second pass over substantially the same area of the tangible medium while moving in the first direction, and wherein the first light source is on and second light source is off for at least part of the first pass and wherein the first light source is off and second light source is on for at least part of the second pass.

28. The method of Claim 22, wherein the tangible medium moves in a first direction and in a second direction, wherein the tangible medium makes at least a first pass and a second pass such that the sensing circuitry senses light reflected from substantially the same area of the tangible medium while moving in the first direction, and wherein the first light source is on and second light source is off for at least part of the first pass and wherein the first light source is off and second light source is on for at least part of the second pass.

29. A scanner operable to scan a tangible medium having an image thereon, comprising: a first illumination means for illuminating at least a portion of the tangible medium; a second illumination means for illuminating the at least a portion of the tangible medium wherein the second illumination means produces infrared light; and sensing means for generating a first electric signal responsive to the intensity of light reflected from at least one pixel area of the tangible medium in response to light produced by the first light source, and generating a first data value responsive to the first electric signal, for generating a second electric signal responsive to the intensity of light reflected from the at least one pixel area of the tangible medium in response to light produced by the second light source, and generating a second data value responsive to the second electric signal, and wherein the second data value may be used to predict the existence of a defect in a digital representation of the image.

30. The scanner of Claim 1, wherein the second light source comprises the first light source directed through an infrared filter.

31. The method of Claim 17, wherein the second light source comprises the first light source directed through an infrared filter.