Search engine TinEye finds instances of an image across the web. After signing up for a free account, you upload an image or provide a URL to an existing image on the web and TinEye will search for other places that image exists. How effective is it? To test the system I decided to "face stalk" our very own Gina Trapani using a head shot photo I know she'd used for a variety of interviews in the past. TinEye found a few instances I had overlooked, but ignored other instances that came up under a cursory Google image search.
For instance it caught the head shot attached to the speaking schedule at the 2008 O'Reilly Emerging Technology Conference but missed it from a Geek Illustrated interview and a New York Times interview. Missing the Times article seems like a glaring oversight to a human, but might have an obvious explanation from the standpoint of the search algorithm? Uploading a head shot I took specifically for the post Gina used to introduce me here at Lifehacker yielded a pinpoint accurate link right back to my Lifehacker profile. If you mess around with TinEye, share your results in the comments below. Thanks jsmorley!