title: exif_read_data - Incorrect APP1 Exif Identifier Code
body: <p>I have problem with some of my photos when i want to read EXIF data.</p>
  
  <p>My code below:</p>
  
  <pre><code>$exif_date = exif_read_data($file_path,  'IFD0');
  </code></pre>
  
  <p>With some images i get warrning:
  Message: exif_read_data(001.jpg) [function.exif-read-data]: Incorrect APP1 Exif Identifier Code</p>
  
  <p>My question is: how can I awoid this warrning, can I check somehow if app1 is correct before exif_read?
  Thanks for help.</p>