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 Katrina Kaif !, which shows multiple images related to Paris, the city, as well as Katrina Kaif intermixed. Now try this face search, which shows you only images with Katrina Kaif 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

Simply add &imgtype=face to the URL, and enter. Your new face search results will be displayed.

If you append &imgtype=news to the URL, the new results features images related to the news event.