"Royalty free" is not the same as public domain, most "royalty free" images still need to be licensed for particular uses and come with other restrictions. The only thing royalty free means is that the copyright owner doesn't demand a cut of each sale you make of whatever you used it in.
"Royalty free" is not the same as public domain, most "royalty free" images still need to be licensed for particular uses and come with other restrictions. The only thing royalty free means is that the copyright owner doesn't demand a cut of each sale you make of whatever you used it in.