Fellow Monks:
I am wondering if there is anyone out there amongst my brethern that have had dealings with the Perl module: Image::TestJPG.
This module was recommended to me in a previous post as having the primary function of verify the integrity of a JPEG image file, (which is precisely what I want to do). With a slight little bit of tweaking to see what precisely (with the variables), what things were doing, I ran the test code provided with the documentation on a JPEG image file that was known to be good.

#!/usr/bin/perl -w

use strict;
use Image::TestJPG;
my $file="/main/images/temp/image.jpg";

  # read data from a file
 open(JPEG, "$file") or die "Can't open $file : $!\n";
my $jpgData = <JPEG>;
 close(JPEG);
my $length=length($jpgData);
 print "LENGTH: $length\n";        
  # test the data
 my $rv = Image::TestJPG::testJPG($jpgData,$length);
print "RV: $rv\n";
  # do something based on the return value
 if($rv) {
     print " ... jpeg data is valid ...\n";
 }
 else {
     print "... jpeg data contains errors ...\n";
 }
[download]

According to the documentation for this module, the subroutine testJPG should return a value of 0 if the JPEG is bad, and 1 if it is good; thus in this case setting the variable $rv to 0 or 1 accordingly.
My initial results on the test of the "good JPEG" returned the results of "... jpeg data contains errors ..." . A new this was not correct because a knew for a fact that my JPEG was good. So... I suspected that something was fishy, so I added a diagnostic line to see what was actually being returned by the subroutine:

 my $rv = Image::TestJPG::testJPG($jpgData, $length);
print "RV: $rv\n";
[download]

If things were working properly according to the documentation, I should have gotten a 1 or a 0. Instead all I got was:

Use of uninitialized value in concatenation (.) or string at ./CCIMGVE
+Rtest.pl line 20.
RV:
[download]

This implied to me that something inside the subroutine was going wrong, or perhaps I was missing some subtlety not known to me. At one point I added:

binmode JPEG;
[download]

just after the open statement for reading in the image file, with the line of thought of forcing perhaps the file read into binary; however, this made no difference.

It would be really grat if I could get this module to work like it is supposed to according to the documentation.
FYI: The OS that I am running this is Red Hat Linux 9 and the Perl Version is 5.8.0 .
Thank you in advance for you help, insight and wisdom!