Abstract:
A mail recognition method including the steps of: subjecting images of mail items to at least one first recognition process to generate a first set of data; and subjecting the images unsuccessfully processed by each recognition process to a second recognition process, different from the preceding processes, to generate a second set of data; the process may continue with further different recognition processes. The method according to the invention includes the step of subjecting the images successfully processed by a first recognition process to another recognition and/or checking process so that the recognition results of each image match or are visually checked.

Description:
[0001]     The present invention relates to a mail recognition method.  
       BACKGROUND OF THE INVENTION  
       [0002]     Mail recognition methods are known in which images of mail items undergo a first character recognition process to generate a first set of data representing alphanumeric characters (indicating the postal code, receiver&#39;s address and data) on the mail items.  
         [0003]     The first recognition process is normally an OCR process, and usually succeeds in recognizing the address on the basis of the alphanumeric characters (roughly 10% of the images fail to be recognized, and the recognition error margin of the OCR process is about 2-3%).  
         [0004]     The images the first recognition process has failed to recognize (i.e. about 10%) undergo a second character recognition process, different from the first, to generate a second set of data, obviously also representing alphanumeric characters on the mail items.  
         [0005]     The second recognition process may, for example, be an RCR (Reject Character Recognition) process, which usually succeeds in recognizing 40% of the preceding OCR process rejects.  
         [0006]     There may also be an operator coding process.  
         [0007]     Cascading the above three processes increases the total mail recognition percentage to as much as over 99%, while at the same time reducing the error percentage to less than 0.5%.  
         [0008]     As is known, recognition algorithms may be variously parameterized to improve recognition probability at the expense of recognition accuracy (probability complementary to error probability per recognized volume).  
         [0009]     In some applications, recognition and accuracy percentages may be insufficient to ensure successful follow-up mail processing, such as highly automated sorting processes.  
       SUMMARY OF THE INVENTION  
       [0010]     It is an object of the present invention to provide a mail recognition process designed to ensure highly accurate recognition combined with a high mail item recognition percentage.  
         [0011]     According to the present invention, there is provided a mail recognition method comprising the steps of: acquiring images of mail items, and subjecting said images to a first character recognition process to recognize addresses; and characterized by comprising the step of subjecting the images successfully processed by said first character recognition process to a second character recognition process, different from the first, to recognize an address; and checking to determine whether the results of the different character recognition processes performed on the same image match. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     A preferred, non-limiting embodiment of the invention will be described by way of example with reference to the accompanying drawings, in which:  
         [0013]      FIG. 1  shows, schematically, a mail recognition system implementing the method according to the present invention;  
         [0014]      FIG. 2  shows first steps in the method according to the present invention;  
         [0015]      FIG. 3  shows second steps in the method according to the present invention;  
         [0016]      FIG. 4  shows third steps in the method according to the present invention;  
         [0017]      FIG. 5  shows a table used in the method according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0018]     Number  1  in  FIG. 1  indicates as a whole a mail processing system implementing the method according to the present invention.  
         [0019]     More specifically, system  1  comprises: 
        a first read, recognition and sorting unit  3  receiving a stream F of mail items  7  (letters, postcards, enclosed documents, flats, cellophane-wrapped magazines, unwrapped magazines, catalogues, etc.);     a standby unit  8  receiving mail items  7  from first read, recognition and sorting unit  3 ; and     a second read, recognition and sorting unit  9  receiving mail items  7  from standby unit  8 .        
 
         [0023]     The second read, recognition and sorting unit  9  emits mail items  7  (letters, postcards, enclosed documents, flats, cellophane-wrapped magazines, unwrapped magazines, catalogues, etc.), and possibly also sends them to other units (not shown) for performing known mail processing operations, such as a mail sequencing process.  
         [0024]     The first read, recognition and sorting unit  3  performs the operations shown in the  FIG. 2  flow chart.  
         [0025]     More specifically, these comprise a first block  100  for acquiring (in known manner) an image of a mail item  7  fed to unit  3 .  
         [0026]     Block  100  is followed by a block  110 , in which the acquired image is subjected to a first (known) character recognition process, typically an OCR (Optical Character Recognition) process, to automatically recognize the alphanumeric characters (receiver&#39;s address, postal code, receiver&#39;s identification data) in the mail item image.  
         [0027]     Block  110  is followed by a block  120 , which determines success of the process in block  110 , i.e. whether the address has been recognized automatically from the mail item image. The address is recognized using known processes, which compare components of the acquired address with data in predetermined tables.  
         [0028]     In the event of a positive response (address recognized from the alphanumeric characters and/or bar code (if any) in the image—first process successful), block  120  is followed by a block  130 , which selects another image, if there is one (if there is not, the process ends), and then goes back to block  100 .  
         [0029]     If the address on the mail item is recognized, a first set of recognized data DATA OCR  is generated, is stored in a memory of first unit  3 , and is associated with mail item  7  by an identification code, which is applied physically to the item, e.g. in the form of a bar code. Alternatively, the bar code may be present already; in which case, if it identifies the mail item unequivocally, it is read and used.  
         [0030]     In the event of a negative response (address on the mail item not recognized, or the image not processed in block  110 ), block  120  is followed by a block  140 , in which the current image is subjected to a known second character recognition process (different from the first), typically an RCR (Reject Character Recognition) process, to automatically recognize the alphanumeric characters in the mail item image.  
         [0031]     Block  140  is followed by a block  150 , which (like lock  120 ) determines success of the process in block  40 , i.e. whether an address has been recognized.  
         [0032]     In the event of a positive response (address recognized by the second process), block  150  is followed by block  130 , which selects another image and, as before, then goes back to block  100 .  
         [0033]     If the address on the mail item is recognized, a second set of recognized data DATA RCR  is generated, is stored in a memory of first unit  3 , and is associated with mail item  7  by an identification code.  
         [0034]     In the event of a negative response (address on the mail item not recognized, or the image not processed in block  140 ), block  150  is followed by a block  160 , in which the current image is subjected to a known third character recognition process, involving operator intervention on a video-terminal (not shown), to recognize the address on the mail item.  
         [0035]     A third set of recognized data DATA V-C  is therefore generated, is stored in a memory of first unit  3 , and is associated with mail item  7  by an identification code.  
         [0036]     Block  160  then goes on to block  130 .  
         [0037]     A mail item image is therefore definitely subjected to a first recognition process. If the first process fails, the image is subjected to a second recognition process different from the first. And, if this also fails, the image is subjected to video-coding recognition.  
         [0038]     Standby unit  8  performs the operations shown in the  FIG. 3  flow chart, during which, in the example shown, the mail items are located in the standby unit  8  shown in  FIG. 1 .  
         [0039]     More specifically, the operations comprise a first block  200 , which extracts an image successfully processed by the first process (in block  110 ), i.e. an image whose mailing address has been recognized and for which relative data DATA OCR  is available.  
         [0040]     Block  200  is followed by a block  210 , which subjects the current image to the second, i.e. RCR, recognition process.  
         [0041]     Block  210  is followed by a block  220 , which determines success of the RCR process and whether the address recognized matches the one recognized in the same image by the OCR process (block  110 ).  
         [0042]     In the event of a positive response (RCR process successful, and matching addresses recognized by both different processes), block  220  is followed by a block  230 , which memorizes data DATA RCR , selects another image, and then goes back to block  200  to examine the next image, until all the available images have been examined.  
         [0043]     In the event of a negative response, block  220  is followed by a block  300  (queuing block), which inserts the current image (for which the RCR process and the preceding OCR process in  FIG. 2  give different addresses, or for which the  FIG. 3  RCR process has failed) in a queue to which all the images not recognized by the OCR process in  FIG. 2  (NO output of block  120 ) are sent.  
         [0044]     The queue therefore comprises: 
        images rejected by block  120  operating as shown in the  FIG. 2  flow chart, i.e. the images rejected by the first OCR process on the images, and which were therefore coded by the RCR process (block  140 ) or video-coded (block  160 );     images not recognized by the RCR process in block  210  ( FIG. 3 ); and     images whose addresses recognized in block  210  do not match those in block  110 .        
 
         [0048]     Block  300  is followed by a block  310 , which extracts images from the queue for operator video-terminal checking.  
         [0049]     Images are extracted in such a way as to form homogeneous queues, i.e. containing one city place-name (e.g. a street) and arranged by alphanumerically arrangeable elements, e.g. building numbers.  
         [0050]     The images are displayed on the video-terminal (not shown) so that the addresses can be seen and either accepted or modified by the operator. It should be pointed out that the system provides for displaying the unmatched addresses (e.g. those coded differently by blocks  120  and  210 ), which are conveniently displayed together with the image of the relative mail item.  
         [0051]     The operator may confirm the proposed address, select one of the proposed addresses (in the event of unmatched addresses as described above), alter the proposed address completely, or retrieve the image of a mail item whose address has been altered manually, e.g. to check the proposed address has been altered correctly.  
         [0052]     In other words, the operator may: 
        complete the available data by adding, deleting, or altering the stored addresses; and     select the available data (e.g. in the event the OCR and RCR process results fail to match).        
 
         [0055]     Upon completion of the operations in block  310 , the operator enters an end-of-check command, and block  310  goes on to a block  320 , which stores the addresses DATA CHK  checked by the operator in block  310  and then goes back to block  310  until all the images have been checked.  
         [0056]     Second unit  9  performs the operations shown in the  FIG. 4  flow chart.  
         [0057]     More specifically, these comprise a first block  400 , which acquires (in known manner) another image of a mail item  7  fed to unit  9 , acquires the identification code/s previously applied to the mail item, and is followed by a block  410 , in which the acquired image is subjected to the OCR (Optical Character Recognition) process.  
         [0058]     Block  410  therefore repeats the process already performed by block  110 .  
         [0059]     Block  410  is followed by a block  420 , which determines success of the process in block  410 , i.e. whether the address has been recognized automatically from the mail item image.  
         [0060]     In the event of a positive response (address recognized—first process successful), block  420  is followed by a block  430 , which performs a global statistical mail item acceptance analysis by means of tables, selects another image, if there is one, and then goes back to block  400 .  
         [0061]     If the address on the mail item is recognized, a set of recognized data DATA OCR-2  is generated, is stored in a memory of first unit  9 , and is associated with mail item  7  using the existing identification code.  
         [0062]     In the event of a negative response (mail item address not recognized), block  420  is followed by a block  440 , which subjects the current image to an RCR (Reject Character Recognition) process.  
         [0063]     Block  440  is followed by a block  450 , which stores the previously acquired data DATA RCR-2 .  
         [0064]     Block  450  then goes back to block  430 .  
         [0065]     In other words, the second unit repeats the same automatic OCR and RCR operations performed by first unit  3 , but with no video-coding operations.  
         [0066]     Like those performed by the first unit, the results of the operations performed by the second unit are stored to permit real-time checking by which to sort and statistically control the stored acquired data.  
         [0067]     The object of the method according to the present invention, in fact, is to minimize error. For which purpose, when statistical analysis reveals potentially conflicting situations (e.g. non-matching recognized addresses or identification bar codes which do not conform with the recognition result), the mail items are rejected or sent for checking to a further video-coding station (not shown).  
         [0068]     In addition, the image of a mail item for which a possible double extraction has been determined (in known manner) may be forwarded for operator checking (video-coding). In which case, when a potential double extraction is determined, the mechanical line forwards the mail item to a video-coding recognition system, by which an operator determines the actual nature of the mail item image in question.  
         [0069]     The real-time check is performed using the tables in block  430 .  
         [0070]     The  FIG. 5  table shows an example of one possible check.  
         [0071]     More specifically: 
        row R 1  is selected in the event of only one semiautomatic address recognition (i.e. by video-coding, block  160 — FIG. 2 );     row R 2  is selected in the event of only one automatic address recognition (i.e. by the OCR or RCR process in block  110  or  140 );     row R 3  is selected in the event of two automatic address recognitions by blocks  110  and  210  giving non-matching results; this situation may also be caused, not by the recognition system, but by a double extraction; in which case, even if the recognition system is operating correctly, overlapping of the mail items would result in mismatching;     row R 4  is selected in the event of two automatic address recognitions by blocks  110  and  210  giving matching results; and     row R 5  is selected in the event of operator-entered address data in block  310 .        
 
         [0077]     Columns C 1 -C 27  in the table are selected on the basis of a matrix M, which receives as input data: 
        the comparison between the result of the OCR process in block  410  and the operator-entered result in block  310 ; or     the comparison between the result of the RCR process in block  440  and the operator-entered result in block  310 .        
 
         [0080]     On the basis of the data associated with each mail item image, a row R 1 -R 5  and a column C 1 -C 27  are selected, and the intersection of the row and column indicates a box indicating the operation (sort/reject) to be performed on the mail item.