[Plugin: NextGEN Gallery] Printing Tags instead of Description or Title…

I’d like to print the images’ tags as a caption instead of the description or title. I’ve found where it produces the caption, but I can’t figure out what to put:

imageURL ?>” title=”<?php echo $image->description ?>” <?php echo $image->thumbcode

$image->description is what needs to be changed. I tried $image->tags and $image->tag.