The pdf417_dec program will read in a pgm file produced by a scanof a sheet of paper with a pdf417 barcode symbol on it.  The pdf417_decwill 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) thatmake up the barcode.  You can specify some diagnostic information todetermine if the program is doing the decode correctly.  The scan I usefor the example was read using a flat bed scanner.  The code used isthe same as the barcode in the AIM pdf417 standard writeup.  Usage:   pdf417_dec   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.