how to make default wordpress gallery pagination

i have this code in functions.php, and i want to make pagination on default wordpress gallery, so can you help me to how can i make wordpress gallery pagination, this code is not working…
one page show 20 images per page
help ….

and how can i add pagination in index.php or in main page…

/*FILTER: GALLERY:  --------------------------------------------------------------*/
add_filter('post_gallery', 'filter_gallery', 10, 2);
function filter_gallery()
{
    global $post;

	//GALLERY SETUP STARTS HERE----------------------------------------//
    if (isset($attr['orderby'])) {
        $attr['orderby'] = sanitize_sql_orderby($attr['orderby']);
        if (!$attr['orderby'])
            unset($attr['orderby']);
    }
	//print_r($attr);
    extract(shortcode_atts(array(
		'order' => 'ASC',
        'orderby' => 'menu_order ID',
        'id' => $post->ID,
        'itemtag' => 'dl',
        'icontag' => 'dt',
        'captiontag' => 'dd',
        'columns' => 2,
        'size' => 'thumbnail',
        'include' => '',
        'exclude' => ''
    ), $attr));

    $id = intval($id);
    if ('RAND' == $order) $orderby = 'none';

    if (!empty($include)) {
        $include = preg_replace('/[^0-9,]+/', '', $include);
        $_attachments = get_posts(array('include' => $include, 'post_status' => 'inherit', 'post_type' => 'attachment', 'post_mime_type' => 'image', 'order' => $order, 'orderby' => $orderby));

        $attachments = array();
        foreach ($_attachments as $key => $val) {
            $attachments[$val->ID] = $_attachments[$key];
        }
    }
    if (empty($attachments)) return '';
	//GALLERY SETUP END HERE------------------------------------------//

	//PAGINATION SETUP START HERE-------------------------------------//
	$current = (get_query_var('paged')) ? get_query_var( 'paged' ) : 1;
	$per_page = 24;
	//$offset = ($page-1) * $per_page;
	$offset = ($current-1) * $per_page;
	$big = 999999999; // need an unlikely integer

	$total = sizeof($attachments);
	$total_pages = round($total/$per_page);
	if($total_pages < ($total/$per_page))
	{	$total_pages = $total_pages+1;
	}
	//PAGINATION SETUP END HERE-------------------------------------//

	//GALLERY OUTPUT START HERE---------------------------------------//
    $output = "<div class=\"gallery-images\">\n";
	$counter = 0;
	$pos = 0;
    foreach ($attachments as $id => $attachment)
	{	$pos++;
        //$img = wp_get_attachment_image_src($id, 'medium');
		//$img = wp_get_attachment_image_src($id, 'thumbnail');
        //$img = wp_get_attachment_image_src($id, 'full');	

		if(($counter < $per_page)&&($pos > $offset))
		{	$counter++;
			$largetitle = get_the_title($attachment->ID);
			$largeimg = wp_get_attachment_image_src($id, 'large');
			$img = wp_get_attachment_image_src($id, array(100,100));
			$output .= " <a href=\"{$largeimg[0]}\" title=\"{$largetitle}\"><img src=\"{$img[0]}\" width=\"{$img[1]}\" height=\"{$img[2]}\" alt=\"\" /></a>\n";
		}
    }

    $output .= "<div class=\"clear\"></div>\n";
    $output .= "</div>\n";
	//GALLERY OUTPUT ENDS HERE---------------------------------------//

	//PAGINATION OUTPUT START HERE-------------------------------------//
	$output .= paginate_links( array(
		'base' => str_replace($big,'%#%',esc_url(get_pagenum_link($big))),
		'format' => '?paged=%#%',
		'current' => $current,
		'total' => $total_pages,
		'prev_text'    => __('«'),
		'next_text'    => __('»')
	) );
	//PAGINATION OUTPUT ENDS HERE-------------------------------------//

    return $output;
}

/*FILTER: GALLERY:  --------------------------*/