If you're using the photos merely for reference to shape the mesh appropriately they don't even have to be in color. Shaping the mesh and building the texture are two different parts of the process. You don't necessarily have to use the same photos to perform the two tasks. And of course, using photos from the internet for both mesh manipulation reference and making textures is legal. Yet another link, for those whose reading comprehension skills are up to it, on the well established concept of fair use. http://www.umuc.edu/library/copy.html