A few years back I found myself wanting to know where a picture came from…and there really wasn’t anything that could do it.

Then came Tineye.com. They use a search function that could identify likenesses of your image to other images on the Internet. By their own description “TinEye creates a unique and compact digital signature or ‘fingerprint’ for it, then compares this fingerprint to every other image in our index to retrieve matches. TinEye can even find a partial fingerprint match. Our fingerprinting technologies have been developed by Idée Inc..”

It worked fairly well the few times I tried it. I found for commercial images I always got the result I wanted. If I was trying to match a photo of a person or something more obscure I generally got nothing.

Then Google came along with their version and it worked REALLY well. Possibly because Google has permissions into more places and more powerful servers to cache and search existing images. You might have noticed now when you search for images on Google there is a little blue camera icon, that is where you can upload your photo for the reverse search. http://images.google.com/ 

I think both of these services are limited by what they can peer into. For instance, if you were sent a photo from someone’s Facebook page, but their profile or photos were set to private, I don’t think Google Images or Tineye.com can peer into those private accounts and match up your photo.

One of the great things about Google Images I’ve found is that if you get a photo and want to know where it originated, sometimes you can do a search, then sort the results by date and find the oldest search result for an image and get an idea of where it might have started.

Another great use is when you get a low res version of a photo and want something higher you can search using the low res and then sort the results or filter by image size.

I’ve heard of people using it for dating purposes, someone you have found online sends you a photo you can search to see where else that photo might appear…interesting possibilities there.

In all, these tools become more and more useful once you realize you have them at your disposal, you will think of reasons and ways to use them.