You already have this one. It comes with Photoshop, but you might not know what it does. It's not exactly a filter because it doesn't change your picture. Instead, it protects your work by placing a digital watermark on it, and a copyright symbol © in the title bar. When you register with Digimarc, they'll send you an ID that will let you embed the digital copyright information into the file. When someone views a Digimarc watermarked file in Photoshop, they'll see a dialog box like the one in Figure 19.13, directing them to the website for more information. No one should use your work without your permission.