How to Search Faces with Google Images

I came across a wonderful tip which allows you to search for faces and portrait images using Google Image Search. Try searching for Paris (Hilton!), which shows multiple images related to Paris, the city, as well as Paris Hilton intermixed. Now try this face search, which shows you only images with Paris Hilton face photos. How to do this?

Google Blogoscoped got tipped from a Google engineer that

“And now, Google Images allows you to restrict your search to a specific category albeit in an unofficial mode only and one of these categories may well be powered by actual image recognition (as opposed to textual keyword analysis).”

How does this face recognition search work?

If the normal search url looks like this
http://images.google.com/images?q=paris

Simply add &imgtype=face to the URL, and enter. Your new face search results will be displayed.
http://images.google.com/images?q=paris&imgtype=face

If you append &imgtype=news to the URL, the new results features images related to the news event.
http://images.google.com/images?q=paris&imgtype=news

This reminds me of Riya Visual Search, another cool face recognition photo search tool. Try out the Google Image Labeler and help improve image search results. I highly recommend you try out Imagery, a powerful alternative Google Image Search interface.