Hello, Do you want to use an image and would like to know if it is copyrighted? This was a hard boring thing to do, however, I have found an online tool which allows you to check if you are free to use any kind of image. Have a look at it! http://www.tineye.com/
tinyeye is a REVERSE image search this wont' tell if the image is copyright or not in legal terms, all images are copyrighted the moment they are created ( or clicked) you have to BUY the rights from the copyright holder so all the sites using google images and posting it on their blogs , are actually i'llegal, its just that the copyright holder, does not enforce the copyright. doesnt' make it legal.
Hello, This 'copyright' use you are telling is quite subjetive. We are talking about real copyrighted images, that when using them you can get in legal trouble. The easiest way to tell if you may be infringing copyright is look at the oldest image and see where it links to. If it something like getty images then best not use it.
I think a Copyright sign on image appears when the copyright owner don't wants the image to circulated over web.