A colleague asked about how to identify potential copyright infringers on the internet. There are a number of ways to do so. One method uses a reverse image search engine (link to article identifying 8 such engines). These engines have indexes of images generated by crawling the internet, and they search their index for images that are similar to the original image.
Two engines that I prefer are:
2. Google's reverse image search (link to the instructions) through its image search engine.