Drupal 7 image gallery output

gistfile1.php

// Requires Content Type with image field with multiple images as described here: http://drupal.stackexchange.com/a/5901
// Title is output as caption if there is title text
// Image size is determined by custom image style in Drupal admin named "gallery_thumb"

<?php
  $gallery_images = $node->field_gallery_image['und'];
  for($i = 0; $i < count($gallery_images); $i++) {
    $image = $gallery_images[$i];
    $output = '<a href="' . file_create_url($image['uri'])  . '">';
    $output .= '<img src="' . image_style_url("gallery_thumb", $image['uri']) . '">';
    if($image['title'] != ""){
      $output .= '<span>' . $image['title'] . '</span>';
    }
    $output .= '</a>';
    echo $output;
  }
?>