Well, I see that the issue is not clear at all� so I guess I will keep away from this approach for now, but the attitude that tracing Mona Lisa is somehow ugly is a little funny to me in the light of the fact that a lot of renaissance painters used projection devices and traced outlines of their subjects - Leonardo likely did the same thing. Unless you have been in Louvre all you have ever seen are the copies� The whole creative process is a recombination of copies. The nature of creative process in itself is protein encoded copy passed via copying mechanism of DNA. Do you want to create something original? Then get yourself some random number generator�

 I know, I know� clipart collections look atrocious� with this I agree� but hey, go to Wal-Mart and see what customers buy� sometimes I think "the uglier the better"� Original Mona Lisa would probably be rejected by microstock agencies as a thing of  "little commercial value"�  In order to survive Leonardo would have to paint a lot of colorful blurs and zombified grinning clerks� that what sells� I wish we could trace more - and learn a thing or two from past� but no� let us be creative and run Difference Cloud filter over a gradient� LOL

Thank you for all of your prompt and helpful responses. I will visit the above-mentioned sites and look closer at their license agreements. Thank you again.