I would probably have at least 3 tables, including the table with the images.
images - probably the table you already have for all images in the gallery
albums - info that describes each album
image_to_album - could just be 2 columns: image_id and album_id (the primary keys from the other 2 tables)
For the "cover photo", I'm undecided right now whether I would make that a 3rd column in the image_to_album table or a column in the albums table, though I think I'd go with the albums table as that automatically limits you to one cover photo per album.