Suggested php code to read file rating set by Adobe Bridge CS3

Question

Background: I have been attempting to read the rating that is assigned in Adobe Bridge CS3 using the creative commons Metadata toolkit for php without success. I am using shared hosting so I do not have an oppotunity to recompile php with different modules.

Is php code available that could be used to read the rating that is embedded in the .jpg file? I have read that this is an xmp (xml) formatted section within the file.

Answer 1

I'm posting my solution here in case someone else has a similiar problem and reads this thread. Here is what I found:
Windows Vista add the rating to the exif section embedded in the file
Adobe Bridge adds another section to the jpg file that contains data formatted in xml. The xml + data structure is referred to as the xmp file. I hadn't yet processed the file with Adobe bridge, that is why I was unable to read the xmp data with the Metadata toolkit.

Using the Creative Commons - Metadata toolkit I was able to read the ratings using the following code. This code is part of a Drupal Module, some of the referenced variables are Drupal settings: variable_get() is a Drupal function to read a variable from a perssistent data store.

include_once("PHP_JPEG_Metadata_Toolkit_1.11/JPEG.php");
  include_once("PHP_JPEG_Metadata_Toolkit_1.11/Photoshop_File_Info.php");
  include_once("PHP_JPEG_Metadata_Toolkit_1.11/EXIF.php");
  include_once("PHP_JPEG_Metadata_Toolkit_1.11/XMP.php");

  $photodir = variable_get('rotate_images_sourcefiles_dir',"sites/default/files/imageNodes");

  $rating_threshold = variable_get('rotate_images_rating_threshold',3);
  $allImages=dir($photodir);
  $filenames = scandir($photodir);

  foreach($filenames as $filename){

    $rating = null;
    $info = pathinfo($filename);
    if (strtolower($info['extension'])=="jpg"){
      //  First try to get the rating from the EXIF data, this is where it is stored by Windows Vista
      $exif = get_EXIF_JPEG( $photodir . "/" . $filename );
      $rating = $exif[0][18246]['Data'][0];

      $jpeg_header = get_jpeg_header_data($photodir . "/" . $filename );
      //  If no rating was found in the EXIF data, it may be in the Adobe format xmp section
      if ($rating == null){
        if($jpeg_header != false){
          $xmp = get_XMP_text($jpeg_header);
          $xmpArray = read_XMP_array_from_text($xmp);
          $rating = $xmpArray[0]['children'][0]['children'][0][attributes]['xap:Rating'];
        }   
      }
    }
  }

I did need to modify the EXIF_Tags.php file in the metadata toolkit by adding an additional entry to the EXIF Tags array. I reported this to the author, but I don't believe he is maintaing the module any longer. The source is on sourceforge, but I don't know how to post a patch. So you may need to make the change to EXIF.php yourself to make the code work.

'EXIF' => array (

// Exif IFD

18246 => array ( 'Name' => "Rating",
                'Type' => "Numeric" ), 

Answer 2

Theoretically if you use fgets you should be able to read it. It would be helpful if you know where this section begins in terms of bytes into the file.