The scripts run.test1, run.test2 and run.test3. show the usage  of pdf417_dec program.  The first runs a simple test from the AIM  spec of a simple barcode.  The second runs a test of a barcode that  I had on the back of a badge given to me at a computer show.  The  third test shows the same barcode, but uses the pdf417_dec to show  the .pgm for each col and for each module broken down.  These files  are easily displayed using gimp.  The input .pnm files were just what is produced from scanning the barcodes  using a flatbed scanner.  I used xscanimage at about 300 dots/ inch.  You could use a higher res, but the scanned image files can become too big.  I scan using greyscale 0-255.  The .pnm image file input to the program  must be greyscale.  Also, the barcode must be surrounded about 20%  whitespace.  For each test, a out.txt file is produced.  They are then copied to  pnm1.txt and pnm2.txt to show the text for the different barcodes.  To run this you need to install netpbm package 10.24.  Make sure to  install the shared and linked libraries in /usr/lib and to add all  the include files in /usr/include before compiling the pdf417_dec  program ( in frontend_src directory ).