Abstract:
A method for linking front and rear images in a document processing system involves linking the front and rear images by a magnetic ink character code line. The document processing system includes an imaging device and a magnetic ink character recognition (MICR) reader. The method comprises capturing a first image and first MICR waveform for the front side of the document, and capturing a second image and second MICR waveform for the rear side of the document. A forward recognition algorithm is applied to the first waveform to produce a first code line. A reverse recognition algorithm is applied to the second waveform to produce a second code line. The reverse recognition algorithm considers the second waveform as resulting from the document being read from the rear side of the document when processing the second waveform.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to document processing, document imaging, and magnetic ink character recognition. The invention further relates to hand-operated document readers/imagers, and to methods and systems for linking front and rear images in a document reader/imager. 
     2. Background Art 
     A typical document processing system includes a feeder and a separator in the document-feeding portion of the system, and a series of roller pairs or belts in the document-transporting portion of the system. In the feeding portion of the system, the feeder acts with the separator to feed documents singly, in order, from a stack. In the transporting portion of the system, the roller pairs and/or belts convey the documents, one at a time, past other processing devices such as readers, printers, and sorters that perform operations on the documents. The feeder is typically a feed wheel, but may take other forms. The separator may be a wheel, but also may take other forms such as a belt. Further, the components in the transporting portion of the system may take a variety of forms. 
     In addition to large document processing systems that handle stacks of documents, smaller systems also exist. These smaller document processing systems may handle smaller stacks of documents, or may even handle single documents, fed one at a time. There are also hand-operated document readers/imagers. 
     Banks, credit unions, and other financial institutions use document processing systems to regularly process checks, deposit slips, and other types of bank documents in order to execute financial transactions efficiently. Document processing systems have therefore become quite prevalent in the industry. Typically, information is printed on these documents in magnetic ink which can be read both by the human eye and a computer. This form of printing is read by a process called magnetic ink character recognition (MICR). As part of the recognition process, a MICR magnetic read head is used to read the information printed on the document. 
     Conventional approaches to MICR reading and recognition generally involve determining peak position information for a waveform generated by a single gap magnetic read head. This peak information typically includes information regarding the amount of time between the peaks of each character. Knowledge of the velocity of the document (and thus, the velocity of the characters which are printed on the document) allows this time information to be converted into distance information, which can be compared to the MICR character peak profiles as contained in the ANSI X9.27-2000 “Print and Test Specifications for Magnetic Ink Printing (MICR)” as promulgated by the American National Standards Institute. Based on the design of the standard E-13B character set, in order that a MICR reader reliably read with a high correct character read rate and with a very low substitution rate, the document velocity must be precisely known during reading or otherwise be speed-controlled so that it does not vary. 
     These conventional approaches are acceptable when the velocity of the document is either known or can be controlled. In fact, conventional approaches to MICR typically involve rather complex schemes for controlling the velocity of the document or attempting to measure its velocity at different times as the document moves past the MICR read head. There has also been an approach to MICR reading and recognition that utilizes a dual gap read head to eliminate the need for precise knowledge or control of the document velocity. 
     In a hand-operated document reader/imager, the document is placed on a base and the MICR/image device is moved over the document from right to left, which is the traditional direction of larger document readers. During this movement, the MICR characters are recognized and the front image of the document is captured. 
     In order to capture the rear image of the document, the document must be removed from the base of the hand-operated check reader/imager, flipped over, and placed back on the base. This manual step in the processing could lead to errors. The operator could place a different document on the base. 
     For the foregoing reasons, there is a need for a method that will verify that the original document was placed back on the hand-operated check reader so as to avoid the accidental association of a front image with an incorrect rear image. 
     SUMMARY OF INVENTION 
     It is an object of the invention to provide an improved method and system for linking front and rear images in a document reader/imager that reduce the likelihood of accidentally associating a front image with an incorrect rear image. 
     The invention comprehends linking the front and rear images with the MICR code line. According to the invention, during the capture of the front image, the MICR code line is read/recognized (converted to text characters) according to a traditional, “forward” MICR algorithm. During the capture of the rear image, the MICR code line is read/recognized (converted to text characters) according to a “reverse” MICR algorithm. 
     The “reverse” MICR algorithm compares the MICR signal from the document with patterns that are expected when the document is processed backwards. These patterns include the MICR signal being reversed and inverted, having a lower amplitude, and having lower quality. If the “reverse” MICR algorithm is successful in recognizing each character, then this result can be used confidently for the document. 
     The code line obtained during the front image capture and the code line obtained during the rear image capture are then compared. If the code lines do not match, this indicates an error and the operator may be instructed to check the document. The front image of the document could be displayed to the operator in order to prompt the operator to locate the correct document for rear image capture. 
     The advantages associated with embodiments of the invention are numerous. For example, methods and systems of the invention for linking front and rear images may be utilized in hand-operated document readers/imagers to assure that the same document is used for the front capture and corresponding rear capture. Further, methods and systems of the invention may also be utilized in other document processing systems to provide additional data integrity. That is, embodiments of the invention may be employed in hand-operated document readers/imagers, and may be employed in document processing systems including automated document readers/imagers when both sides of the documents are read using either multiple devices or a multiple-pass approach. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows the outline and shape of the fourteen characters and symbols which are called the E-13B MICR character set as used on many financial payment documents; 
         FIGS. 2A-2N  show the set of waveforms for the E-13B characters and symbols as read from a responsive magnetic signal gap read head when the magnetized characters are passed by the magnetic read head; 
         FIG. 3  is a cross-section view of a read head, which is one example of a suitable read head for reading magnetic ink characters; 
         FIG. 4  illustrates a hand-operated document reader/imager made in accordance with the invention; 
         FIG. 5  is a block diagram illustrating a system for linking front and rear images in the hand-operated document reader/imager; 
         FIG. 6  is a flow chart illustrating a method for linking front and rear images in the hand-operated document reader/imager; 
         FIG. 7  illustrates a waveform for magnetic ink characters/symbols  3 ,  5 ,  7 , Amount when the document containing the characters/symbols is inserted face up for front image capture in the hand-operated document reader/imager, and the magnetic ink characters/symbols are passed over from right to left; and 
         FIG. 8  illustrates a waveform for magnetic ink characters/symbols  3 ,  5 ,  7 , Amount when the document containing the characters/symbols is inserted face down for rear image capture in the hand-operated document reader/imager, and the magnetic ink characters/symbols are passed over from right to left and read in reverse order. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  illustrates the E-13B character set at  50 . The character set  50  contains ten characters and four symbols as defined in the ANSI X9.27-2000 “Print and Test Specifications for Magnetic Ink Printing (MICR).” When used on a document for automated machine reading, the characters and symbols in the set must be printed using magnetic ink. ANSI X9.27 defines the dimensions of each character/symbol and the expected nominal waveform peak position and relative amplitude of waveform peaks. 
       FIGS. 2A-2N  demonstrate the waveform details of each of the characters/symbols shown in  FIG. 1  when each character/symbol is moved past a single gap magnetic read head at a given constant velocity.  FIG. 2A  shows the waveform  60  for the character “1” as the character is moved past the read head.  FIG. 2B  shows the waveform  62  for the character “2” as the character is moved past the read head.  FIG. 2C  shows the waveform  64  for the character “3” as the character is moved past the read head.  FIG. 2D  shows the waveform  66  for the character “4” as the character is moved past the read head.  FIG. 2E  shows the waveform  68  for the character “5” as the character is moved past the read head.  FIG. 2F  shows the waveform  70  for the character “6” as the character is moved past the read head.  FIG. 2G  shows the waveform  72  for the character “7” as the character is moved past the read head.  FIG. 2H  shows the waveform  74  for the character “8” as the character is moved past the read head.  FIG. 2I  shows the waveform  76  for the character “9” as the character is moved past the read head.  FIG. 2J  shows the waveform  78  for the character “0” as the character is moved past the read head.  FIG. 2K  shows the waveform  80  for the symbol “R-T” as the symbol is moved past the read head.  FIG. 2L  shows the waveform  82  for the symbol “Amount” as the symbol is moved past the read head.  FIG. 2M  shows the waveform  84  for the symbol “On-Us” as the symbol is moved past the read head.  FIG. 2N  shows the waveform  86  for the symbol “Dash” as the symbol is moved past the read head. 
     In most applications, the characters are first magnetized prior to the characters being presented past the read heads. As shown, each unit on the x-axis represents 0.013 inches. The first character peak is aligned with the first position and the remaining peaks generally align with other vertical grid lines because the MICR characters/symbols are designed using increments of 0.013 inches in the horizontal direction. For those cases where the change in magnetic flux is not perfectly aligned, it is caused by the effects of the radii shifting the position of the maximum rate of change to the left. 
     Examples are the character “3”,  FIG. 1 , with the six radii at the left of the character and the character “0”,  FIG. 1 , with the large interior radii and large outside radii at the left hand stroke. The waveform  64  in  FIG. 2C  illustrates the fourth peak shift to the left for the character “3” and the waveform  78  in  FIG. 2J  shows the left shift of both peaks three and four for the character “0”. Normally, in order to produce waveforms where the peaks correspond to known dimensions such as 0.013 inches, the velocity of the characters passing the read heads must be precisely set. Otherwise, the character peaks will be out of scale. 
     In  FIG. 3 , a read head is generally indicated at  100 , and includes a gap  102 . The read head utilizes sensing coil  106 . Core  110  forms a path for the magnetic flux changes experienced when the reader passes over magnetic ink. Of course, it is appreciated that alternative readers may be used, and any suitable technique may be utilized for assuring that flux variation from the magnetic ink characters is sensed. 
     An exemplary embodiment of the invention is illustrated in  FIGS. 4-8 .  FIG. 4  illustrates a hand-operated document reader/imager  120 . Document reader/imager  120  includes a moving MICR/image subsystem  122 . Subsystem  122  includes a contact image sensor  124  and a MICR read head  126 . Contact image sensor  124  captures an image of the document  140  when subsystem  122  is moved across the document  140 . Contact image sensor  124  captures the front image of the document  140  when the document  140  is placed face-up on the base of the reader/imager  120  and the MICR/image subsystem  122  is moved from right to left over document  140  as indicated by arrow  128 . To capture the rear image of document  140 , document  140  is removed from the base of the reader/imager  120 , flipped over, and placed back on the base of reader/imager  120 . Thereafter, contact image sensor  124  captures the rear image of the document  140 , with the document  140  being face-down on the base of reader/imager  120 , when MICR/image subsystem  122  is moved from right to left over document  140  as indicated by arrow  128 . 
     MICR read head  126  is for reading the magnetic ink character data  142  on document  140 . During the front image capture, the MICR code line is read according to a traditional, “forward” MICR algorithm as MICR read head  126  passes from right to left over the magnetic ink character data  142  on document  140 . During the rear image capture, the MICR code line is read according to a “reverse” MICR algorithm as MICR read head  126  passes from right to left over document  140 . In this way, the characters are read in reverse order. In order to read the MICR code line during rear image capture, the “reverse” MICR algorithm compares the MICR signal from the document with patterns that are expected when the document is processed from the back. 
       FIG. 5  is a block diagram illustrating a system for linking front and rear images in the hand-operated document reader/imager by using the MICR code line to link the front and rear images. As shown, the document  140  is placed on the base of the reader/imager for front image capture, and then flipped over and placed back on the base for rear image capture. Moving MICR/image subsystem  122  is moved across the document as indicated by arrow  128 . Block  150  represents the MICR reading and recognition logic. Logic  150  includes a traditional, “forward” MICR algorithm as understood by one of ordinary skill in the art. 
     In the traditional, “forward” MICR algorithm, the waveform obtained from the read head  126  is compared against known MICR character peak profiles  152  ( FIGS. 2A-2N ). If the recognition is successful, the MICR reading and recognition logic  150  determines the recognized MICR characters  154 . The traditional, “forward” MICR algorithm is applied during the front image capture by image sensor  124  of a face-up document. 
     In accordance with the invention, logic  150  further includes a “reverse” MICR algorithm that is utilized to process a face-down document during rear image capture. More specifically, when a document/item that is being read by read head  126  and processed by reading and recognition logic  150  is a document that is face-down for rear image capture, the waveform obtained from the read head  126  is compared against patterns that are expected when the document is processed face-down, that is, backwards, with the magnetic ink characters being read in reverse as read head  126  passes from right to left over the document  140 . The face-down document will generate a waveform that is reversed and inverted. The waveform is reversed because the characters/symbols will be read in the reverse order as the read head passes over the document because the document is face-down. Because the flux change when the leading edge of the character string reaches the read head is positive, the first sensed peak is always a positive peak. Accordingly, when the document is face-down, the waveform is inverted. In addition, the waveform will likely have reduced amplitude and signal quality due to the read head  126  reading through the document  140  because the magnetic ink is on the far side of the document due to the document being oriented face-down. 
     In the “reverse” MICR algorithm, the waveform obtained from the read head  126  is still compared against known MICR character peak profiles  152  ( FIGS. 2A-2N ); however, consideration is given to the fact that the waveform is reversed, inverted, and possibly has reduced amplitude and signal quality due to the document being face-down for rear image capture. If the recognition is successful, the MICR reading and recognition logic  150  determines the recognized MICR characters  154 . 
     In accordance with the invention, the MICR code line recognized during the front image capture and the MICR code line recognized during the rear image capture are compared to assure that the same document was used for front and rear image capture. More specifically, the front and rear images are linked by the MICR code line. If the code line recognized during front image capture does not agree with the code line recognized during rear image capture, this indicates an error and an operator may be instructed to check the document. The front image of the document may be displayed to the operator in order to prompt the operator to locate the correct document for rear image capture. 
     It is appreciated that one approach to implementing the invention requires that both MICR code lines are fully recognized and match each other to assure that the same document is used for both front image capture and rear image capture. However, it is appreciated that the MICR code line obtained during front image capture may be deemed to be the correct code line, and the MICR code line obtained during rear image capture need not be fully recognized. Put another way, a partial recognition of the MICR code line during rear image capture may be sufficient to verify that it is in fact the same document as used previously for the front image capture. For example, some applications may only require that a predetermined percentage of the characters match. In addition, it is to be appreciated that methods and systems of the invention may be utilized in other document processing systems to provide additional data integrity, including systems that have automated document readers/imagers when both sides of the documents are read using either multiple devices or a multiple-pass approach. 
       FIG. 6  is a flow chart illustrating a method for linking front and rear images in the hand-operated document reader/imager in accordance with the invention. At block  170 , the document image and MICR waveform are captured for the front of the document. At block  172 , the traditional, “forward” MICR algorithm is applied to compare the waveform obtained during front image capture to the known MICR character peak profiles. At block  174 , the document image and MICR waveform are captured for the rear of the document. At block  176 , the “reverse” MICR algorithm is applied. 
     The waveform obtained during rear image capture is still compared against the known MICR character peak profiles, but the waveform is compared against patterns that would be expected when the document is processed from the back. Put another way, the backwards document produces a reversed and inverted waveform. This waveform may be corrected and then compared against the normal peak profiles, or the uncorrected waveform may be compared against a set of modified peak profiles. The particular details of the comparison may vary, with the important fact being that consideration is given to the fact that the original waveform is reversed, inverted, and possibly has reduced amplitude and signal quality due to the document being read from the back. 
     At block  178 , the MICR code line obtained during the front image capture (as determined by the “forward” MICR algorithm at block  172 ) is compared to the MICR code line obtained during the rear image capture (as determined by the “reverse” MICR algorithm at block  176 ). According to decision block  180 , if the code line recognized during front image capture does not agree with the code line recognized during rear image capture, this indicates an error and an operator may be instructed to check the document as depicted at block  184 . In the event that the code lines agree, normal document processing continues as indicated at block  182 . 
       FIG. 7  illustrates a waveform  190  for magnetic ink characters/symbols  3 ,  5 ,  7 , Amount when the document containing the characters/symbols is inserted face up for front image capture in the hand-operated document reader/imager, and the magnetic ink characters/symbols are passed over from right to left. When this same document is read during the rear image capture, the waveform becomes reversed and inverted.  FIG. 8  illustrates a waveform  200  for magnetic ink characters/symbols  3 ,  5 ,  7 , Amount when the document containing the characters/symbols is inserted face down for rear image capture in the hand-operated document reader/imager, and the magnetic ink characters/symbols are passed over from right to left and read in reverse order. As shown, waveform  200  is reversed with respect to waveform  190  because the characters/symbols are read in the reverse order due to the document being oriented face-down. In addition, waveform  200  is inverted with respect to waveform  190  because when the edge of the character string reaches the read head, the first peak is positive due to the sensed increase in magnetic flux. Finally, waveform  200  has reduced amplitude with respect to waveform  190  due to the read head having to read through the document to read the characters. 
     While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention.