Robert_Charlton - 6:06 am on Aug 10, 2013 (gmt 0)
...uses something called "keyword albums", which are keyword links on every page that link to an album of images tagged with that tag on the fly.
ichthyous - This sounds essentially like search-generated tag pages, a combination which IMO is guaranteed to get you into trouble with Panda.
Tag pages generally end up being very thin pages unless they're predefined and prioritized, with their number strictly limited. They're generally not integrated well structurally into the site... and generating them on the fly introduces several levels of randomness and confusion into how Google sees what your site is about. Keyword tags are pretty likely to be superficial.
...I am wondering if blocking them in robots.txt might help me to recover.
This would perhaps be the worst way of dealing with them. You'd be sending your link juice, which ought to go into a well-conceived navigation structure, into a black hole.
Better than robots.txt would be to use the robots meta tag with "noindex,follow" as attributes. The "follow" attribute is a default, but many webmasters choose to use "nofollow" in this situation, so I thought I'd note the choice.
IMO, noindex is only a temporary fix, but at least with "noindex,follow" you'd be recirculating your link juice throughout the site, rather than throwing it away completely as you would with robots.txt blocking the tagged "keyword albums".
Those tag links, though, would still be on your pages... most likely providing too many choices for users, and you'd be throwing away most opportunities you have to prioritize the navigation on your site. I realize that this is what you thought that the tags would be doing... but tags are simply a superficial approach to a much more complex problem. I'm guessing also that Panda doesn't do well with a somewhat randomized "on the fly" structure.
So, I'd suggest getting rid of "keyword albums" entirely, and looking into other, more solid approaches to structuring your navigation and to providing an engaging experience for your visitors.