NB: You shouldn't use System.Drawing in a web app. It can lead to memory leaks and lots of pain. Even the newer WPF equivalents are not safe for use on a web server.
Unless you have a good reason to then I would recommend against rolling your own (with any library). Use an existing cloud service that specializes in it.
Most b2b saas products have a specific reason to not use a third party for everything - their customers don't want their data sprayed everywhere. Add to that anyone with a government contact.
Any of the ones listed in the article?