Looking for companies who detect copyright infringement on the internet?

[Alexa]

I am looking for companies that use images from professional photographers and look online for copyright infringements. I do know the big ones already, like Picscout, Pixray, Corrigon, But I would like to find more of these companies to be able to make a comparison between their services and prices.
P.S.: I know there are services out there where you can look for your pictures like Google etc. But when this concerns a stock of a couple of thousand images, you need a service provider who offers this service for you

[Sean K]

You can drag an image into Google image search. You'll see everyone that uses the image for free.