frontend.txt

PDF417编码的算法的源程序

  The frontend program will read in a pgm file produced by a scan
of a sheet of paper with a pdf417 barcode symbol on it.  The frontend
will find the pdf417 barcode on the page, orient it so it can be read,
and will figure out the values for the modules ( 17 wide bar codes) that
make up the barcode.  You can specify some diagnostic information to
determine if the program is doing the decode correctly.  The scan I use
for the example was read using a flat bed scanner.  The code used is
the same as the barcode in the AIM pdf417 standard writeup.


  Usage:   frontend   infile  [1-7]


  infile is the name of the input pgm format file.

  and optional number from 1 to 7 follows.  The output of the
  program will include the file out.data ( the data for the codes ).
  Plus the following output according to the optional number.


      1        An output file for each of the modules in pgm format
                            ( outmoduleXX_YY.pgm)
      2        An output file of the final unslanted barcode. (outf.pgm)
      3        Both 1 and 2 above
      4        An output file for each column of the barcode (outcolx.pgm)
                 and an output file of the barcode before unslanting (out.pgm)
      5        Both 1 and 4 above
      6        Both 2 and 4 above
      7        All three 1 and 2 and 4 above
  

  The format of the out.data file is :

  row number :  column number :  code 
  
  where code is from 0 - 2789 ( if a valid code )
             or      9999     ( is an invalid code or erasure )


   The out.data file can be fed into the scan program for further processing
   to show the text of the message that was encoded into the barcode.