function generate_thumb_image($file_path, $size, $value, $output = '')
 {
     $extension = end(explode(".", $file_path));
     switch ($extension) {
         case "png":
             GDSRGenerator::generate_thumb_png($file_path, $size, $value, $output);
             break;
         case "gif":
             GDSRGenerator::generate_thumb_gif($file_path, $size, $value, $output);
             break;
         case "jpg":
             GDSRGenerator::generate_thumb_jpg($file_path, $size, $value, $output);
             break;
     }
 }