/**
  * @param int $contentObjectId
  * @param string $file
  * @return eZImageFile|null
  */
 protected static function fetchImageFile($contentObjectAttributeId, $file)
 {
     return eZImageFile::fetchObject(eZImageFile::definition(), null, array('contentobject_attribute_id' => $contentObjectAttributeId, 'filepath' => $file));
 }