An artist designs a graphic for a web site. The artist signs a work for hire agreement with the owner of the site, who then becomes the copyright owner of the graphic created. All of these uses are the copyright owners priviledge because he now owns the right to derivative works from the original copyright in the graphic.
Lets say now a third party comes along and visits the owner's web site.
He really likes the graphic and decides to use some elements of it on his own web site. He takes the graphic and makes some significant modifications and posts it on his own web site. Yes he is. No matter how much is changed, the third party can only use the graphic with the copyright owner' s permission. More about contractors and their copyrights.