as you already know, we care a lot about not having double standards and try hard coming up with rules that would respect and satisfy our members' artistic spirit and at the same time not disrespect deviantArt as a community.
The copyright issue is exactly that – a pretty big issue. In deviantArt's rules and guidelines you will read that copyrighted images (such as celebrity photos, screenshots from movies and games, official game covers, etc.) are NOT a valid stock for photomanipulating. We actually agree on that, since every artist would have a problem with people using their work without permission or without giving credit. But it's pretty much impossible for you to ask permission to use, let's say, Lara's official released images for your photomanipulations, hence the rule you can't use them.
However, since this rule is in a way a little bit absurd, we have decided to write a disclaimer about exceptions that can and will be made. We will from now on start accepting photomanipulations which may contain copyrighted material BUT the standards for those will be very strict. We can't write a universal rule about how they will be chosen because every deviation is very different, and when it comes to an issue like this not everything is black and white – there are a lot of grey areas and loopholes on which you'll have to trust us to make the right decision, so we would appreciate it if you weren't to ask us why your deviation was declined (although we always give you feedback when that happens).
So, the exceptions may be done on works that use copyrighted material BUT in a way that the artist has created something completely new and original out of it. Exceptions will NOT be made in case you added a few changes on already existing copyrighted artwork/screenshots/released images, etc., in other words if the copyrighted material remains dominant on your entire work.
Example of work that can be accepted:
Example of work which cannot be accepted:
Also, we would like you not to think that this has anything to do with favoritism – we will be objective when it comes to choosing the deviations.
Thanks for reading, and for understanding!
Skin by JAMsEye and Inna-Vjuzhanina
Special thanks to marioluevanos