Corbis is a stock photo/images agency, one of the largest in the world. It is wholly owned by Microsoft. The “Corbis” watermark on the photo means that whoever put the graphic together just ripped the thumbnail image off the Corbis website instead of paying for and downloading the actual high-res photo. Since such images are easily accessible and are fine for online graphics, Corbis puts a digital watermark over every image on their site to discourage just this sort of piracy. (I used to work for Westlight, a large West Coast stock agency which was absorbed by Corbis several years ago. )