title: Read meta information from PDF using Perl module Image::ExifTool
body: <p>I would like to read meta information from PDF using Perl module <a href="http://search.cpan.org/~exiftool/Image-ExifTool-10.10/lib/Image/ExifTool.pod" rel="nofollow">Image::ExifTool</a>. I need to process PDFs using cross reference streams (as of PDF 1.5), and the other well established modules like PDF::API2 and CAM::PDF seem not to support them or have limited support.</p>
  
  <p>Anyway, Image::ExifTool reads apparently a number of <a href="http://cpansearch.perl.org/src/EXIFTOOL/Image-ExifTool-10.10/html/TagNames/PDF.html" rel="nofollow">PDF tags</a>, but if I run the following code:</p>
  
  <pre><code>use Image::ExifTool qw(:Public);
  my $file = 'file.pdf';
  my $exifTool = new Image::ExifTool;
  $exifTool-&gt;ExtractInfo($file);
  my @tagList = $exifTool-&gt;GetFoundTags('File');
  for (@tagList){
      print "$_\n"
  }
  </code></pre>
  
  <p>I do not seem to be able to get more then these tags:</p>
  
  <pre><code>ExifToolVersion
  FileName
  Directory
  FileSize
  FileModifyDate
  FileAccessDate
  FileCreateDate
  FilePermissions
  FileType
  FileTypeExtension
  MIMEType
  PDFVersion
  Linearized
  Author
  CreateDate
  Creator (1)
  ModifyDate
  Producer (1)
  Subject
  Title (1)
  XMPToolkit
  CreateDate (1)
  CreatorTool
  ModifyDate (1)
  MetadataDate
  Producer
  Format
  Title
  Description
  Creator
  DocumentID
  InstanceID
  PageLayout
  PageMode
  PageCount
  </code></pre>
  
  <p>In particular, I would like to get e.g. the PDF document catalog (Root tag). However running a code like this doesn't return any value:</p>
  
  <pre><code>my $tag = 'Root';
  my $exifTool = new Image::ExifTool;
  my $info = $exifTool-&gt;ImageInfo($file, $tag);
  for (sort keys %$info) {
          print "$_ =&gt; $$info{$_}\n";
  }
  </code></pre>
  
  <p>Help please :-)</p>