content-based image retrieval?

Hello,
I have the feeling this is a FAQ, but I can't find an answer to it anywhere in the Postgres documentation, website, or
google.

Is there anything out there for PostgreSQL for doing content-based image retrieval?  e.g. "select all images that look
likethis one/are the same colors as this one"? 

Google returns a few references to something called Chabot, Virage, and a few other ancient sites, but there's very
littlemeat on anything that even still exists. 

There's a possibility I'll be building such a system, and currently I'm kind of being leaned towards Oracle and it's
interMediastuff.  I'd like to stick with PostgreSQL if possible. 

I'm not a rocket scientist, so I am not under the impression I can build my own CBIR.  I'd like to know if there's
anythingthat actually exists and works that works with PostgreSQL. 

Thanks!