Abstract:
A system for verifying accuracy of a raster scanned image of a document ( 20 ) includes an input tray ( 30 ) that holds documents prior to imaging; an input imaging device ( 40 ) that captures an image of a document in the input tray; transmitting the captured input tray image to an image processor ( 100 ); transporting the document through a document scanner ( 10 ); a raster capture device for capturing a raster scanned image of the document with; transmitting the raster scanned image to the image processor; and verifying the accuracy of the raster scanned image by comparing the raster scanned image of the document to the input tray image of the document.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     Reference is made to commonly-assigned copending U.S. patent application Ser. No. 13/714,885, filed Dec. 14, 2012, entitled METHOD OF CAPTURING AN IMAGE OF A DOCUMENT, by Schaertel et al.; U.S. patent application Ser. No. 13/714,863, filed Dec. 14, 2012, entitled VERIFYING ACCURACY OF A SCANNED DOCUMENT, by Schaertel et al.; U.S. patent application Ser. No. 13/714,926, filed Dec. 14, 2012, entitled SYSTEM FOR CAPTURING AN IMAGE OF A DOCUMENT, by Schaertel et al.; U.S. patent application Ser. No. 12/858,488 (now U.S. Publication No. 2012/0044547), filed Aug. 18, 2010, entitled A DOCUMENT SCANNER, by Schaertel et al.; U.S. patent application Ser. No. 12/839,476, filed Jul. 20, 2010, entitled METHOD FOR DOCUMENT SCANNING, by Schaertel et al.; U.S. patent application Ser. No. 12/839,471, filed Jul. 20, 2010, entitled A DOCUMENT SCANNER, by Schaertel et al.; and U.S. patent application Ser. No. 12/276,641 (now U.S. Publication No. 2010/0127447), filed Nov. 24, 2008, entitled DOCUMENT TRANSPORT APPARTUS, by Hammen; the disclosures of which are incorporated herein. 
     FIELD OF THE INVENTION 
     This invention relates to scanners in general, and in particular to verifying the accuracy of a scanned document. 
     BACKGROUND OF THE INVENTION 
     A document scanner moves a document through a transport path and creates a digital image of the document as it moves. The processor for the document scanner has preset document characteristics and the operator must select functions and features to accommodate the specific requirements for a particular type of document. Alternately, the scanner may default to less efficient settings that will process all documents since scanners are not typically programmed with specific requirements on a document-by-document basis. 
     The preset characteristics include document characteristics such as size, weight, texture; and specific application requirements such as resolution and imaging mode, color, simplex, or duplex. In a document scanner, the documents to be scanned may vary by size, weight, color content, physical condition, or other characteristics, which may require different scanner features to be enabled or operator actions to be employed for the most optimal and efficient mode of operation. Prior knowledge of these many different document attributes can enable the proper selection of scanner features to improve the efficiency of the scanning process or enable other features which may provide specific applications required by a particular type, style, or size of document. Prior knowledge of the documents physical condition can also prompt immediate action from the operator to protect the document or scanner or allow other features within the scanner to perform more reliably. 
     The exit area of the scanner is used for collecting the scanned documents as they exit the transport. A document must also exit the scanner, once it has been imaged, in an orderly fashion. By discerning document characteristics in the input area as well as the exit area, characteristics such as, but not limited to, number of documents, the exit area features which control stacking and tracking can be managed. 
     During the scanning process there are a number of ways in which the information extracted from a scanned document may be inaccurate. The scanned document may be deformed or wrinkled by the document transport system, there may be dust or foreign matter on the image capture optics, the document may be skewed or misaligned, or incorrect scanning features may have been selected, but not limited to, all of which may result in capture of inaccurate information during the scanning process. There exists a need to verify captured image data, especially in high speed document scanners. 
     There have been attempts in the document printing industry to verify information on printed images, but the requirements for printing a document are different than the requirements for accurate scanning of a document. For example, U.S. Publication No. 2008/0013848, discloses a line-by-line scan of a printed document to check for defects such as streaks or banding in the printed document. U.S. Publication No. 2003/0076518, discloses a printer which incorporates a CCD raster capture device which images the output tray. The captured output image is compared to data used to print the document. 
     SUMMARY OF THE INVENTION 
     Briefly, according to one aspect of the present invention a system for verifying accuracy of a raster scanned image of a document includes an input tray that holds documents prior to imaging; an input imaging device that captures an image of a document in the input tray; transmitting the captured input tray image to an image processor; transporting the document through a document scanner; a raster capture device for capturing a raster scanned image of the document with; transmitting the raster scanned image to the image processor; and verifying the accuracy of the raster scanned image by comparing the raster scanned image of the document to the input tray image of the document. 
     The invention and its objects and advantages will become more apparent in the detailed description of the preferred embodiment presented below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view from the side of a transport for a document scanner according to the present invention. 
         FIG. 2  is a perspective view of a scanner output tray according to the present invention. 
         FIG. 3  is a cross-sectional view from the side of a straight through transport of a document scanner according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention will be directed in particular to elements forming part of, or in cooperation more directly with the apparatus in accordance with the present invention. It is to be understood that elements not specifically shown or described may take various forms well known to those skilled in the art. 
       FIG. 1  is a side cross-sectional view of a document scanner  10 . As shown in  FIG. 1 , documents  20  are first placed in the input tray  30  of the scanner  10 . The document is moved forward into the scanner  10  by the urging roller  45 , then the feed roller  50  while additional documents  20  are held back by the separation roller  60 . The document  20  continues through the document transport  70 , is imaged by the front and rear raster capture devices  80  and  90  respectively, and then moves out of the transport exit  130  into the output tray  150 . 
     As, or after, the document  20  exits the transport  70  at the transport exit  130 , the document  20  and the output tray  150  are imaged by the output imaging device  140 . The images are sent to the image processor  100  to discern document  20  and output tray  150  characteristics. 
     One output tray  150  characteristic is whether or not there are documents  20  present in the output tray  150 . If the output tray  150  is determined to be empty the processor  110  will determine how many documents  20  can be scanned before the output tray  150  becomes full. Also determining the output tray  150  level of documents will be used by the processor  110  to stop scanning if the output tray  150  becomes full. This may happen if the operator continues to place documents  20  in the input tray  30  while scanning without removing documents ( 20 ) from the output tray  150 . 
     Another important characteristic is the stacking of the documents  20  in the output tray  150 . If the documents  20  are not laying flat, one on top of another, the processor  110  will stop the scanning process and prevent additional documents  20  from stacking improperly. Improper stacking may be an indication of the controlled output stacking  120  feature not operating properly or being inadvertently turned off. Based on the output tray  150  characteristics, proper adjustment of the output tray side guides  160  or end stop  170  will be determined. The scanning may be stopped for the operator to adjust the side guides  160  or end stop  170 , or an auto adjust feature can be employed to make the correction while scanning is continued. 
     Based on document information from an input imaging device  40  the condition of the document  20  exiting the scanner  10  will be compared to condition of documents  20  entering the scanner  10  to determine if damage to the document  20 , such as bent or torn corners, is occurring within the document transport  70 , as is shown in  FIG. 2 . The processor  110  will then stop the scanning process and alert the operator. 
     Using the information from the input imaging device  40  the number of documents  20  entering the document scanner  10  can be compared to the number of documents  20  exiting the scanner  10 . If the number of documents  20  exiting the document scanner  10  does not match the number of documents  20  entering the document scanner  10  the operator will be alerted to the lost document  20 . 
     In a C-shape document transport  70  the document  20  order can be tracked using document  20  content captured by the output imaging device  140  in conjunction with the rear raster capture device  90 . In document scanner  11 , shown in  FIG. 3 , having a straight through document transport  70 , the document  20  order can be tracked using the document  20  content captured by the output imaging device  140  in conjunction with the front raster capture device  80 . 
     In one embodiment of the invention, an image of a document  20  in an input tray  30  is captured with an input imaging device  40  such as a raster capture device, CCD sensor, or CMOS sensor. The captured input tray image  190  is transmitted to an image processor  100  such as a microprocessor or a computer. The document is then transported through a document scanner  10  which captures a raster scanned image  180  of the document  20  and the raster scanned image  180  is transmitted to the image processor  100 . The image processor  100  verifies the accuracy of the raster scanned image  180  by comparing the raster scanned image  180  of the document  20  to the input tray image  190  of the document  20 . If the raster scanned image  180  of the document  20  does not match the input tray image  190  of the document  20 , scanner  10  functions may be modified or other corrective actions taken. Corrective actions may include rotation of the raster capture device, changing a color capture mode, or cleaning image optics. 
     The input tray image  190  of the document  20  is captured as an area image  210  rather than raster by raster as is typically used to capture the raster scanned image  180  of the document  20 . The input tray image  190  of the document  20  may be low resolution or high resolution. 
     In another embodiment of the invention, the document  20  is moved to an output tray  150  for holding documents  20  after it exits the scanner  10  and an image of the document  20  in the output tray  150  is captured with an output imaging device  140 . The captured output tray  150  image is transmitted to the image processor  100  which verifies the accuracy of the raster scanned image  180  by comparing the raster scanned image  180  of the document  20  to the input tray image  190  of the document  20  and the output tray image  200  of the document  20 . 
     In yet another embodiment of the invention, an image of a document  20  in an input tray  30  for holding documents  20  is captured as an area image  210  rather than raster by raster with an input imaging device  40 . Capturing the image as an area image  210  means that an image of the entire document  20  is taken rather than imaging the document  20  raster by raster, which is the usual way of scanning a document  20 . The captured input tray image  190  is transmitted to an image processor  100  and the document  20  is transported to an output tray  150 . After the first document  20  has been transported out of the input tray  30 , an image of a second document  20  in the input tray  30  is captured and transmitted to the image processor  100 . 
     In a further embodiment, an image of the document  20  in the output tray  150  is captured with an output imaging device  140  and transmitted to the image processor  100 . The accuracy of the input tray  30  image is verified by comparing the input tray image  190  of the document to the output tray image  200  of the document  20 . 
     The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the scope of the invention. 
     PARTS LIST 
     
         
           10  document scanner 
           11  document scanner 
           20  documents 
           30  input tray 
           40  input imaging device 
           45  urging roller 
           50  feed roller 
           60  separation roller 
           70  document transport 
           80  front raster capture device 
           90  rear raster capture device 
           100  image processor 
           110  processor 
           120  controlled output stacking 
           130  transport exit 
           140  output imaging device 
           150  output tray 
           160  output tray side guides 
           170  end stop 
           180  raster scanned image 
           190  input tray image 
           200  output tray image 
           210  area image