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davidcyclebackIf you post on your website a scan of an original drawing your drew or a snapshot of your kitty cat, no one can copy it or use it elsewhere without your permission.
If you post a scan on your website of something that is in the public domain, like the the Mona Lisa, you don't own the image. If anyone owns special rights to the image of the T206 Christy Mathewson baseball card, it would probably be the Mathewson estate, Major League Baseball and SF Giants, not a website owner who bought one of the cards on eBay.