Usually your WordPress theme will have an “attachments.php” page that would have a “single view” of the image in question. For an example: http://twentyelevenphoto.wordpress.com/2011/05/25/an-image/mcm_5276/
That gives you a “single” view of your image as well as comments. To test to see if your site has this, create a gallery and make sure to check “Attachment Page” when setting the Link Thumbnail to option.
Then view the post, click on the gallery image and it should take you to that images single page.