Copyright hinges on the question of ownership of an original piece of work, in this case, graphics. Copyright becomes immediately effective on the creation of the original work, without the creator even registering to protect his work or anything similar. It is already protected by copyright, which means the copyright belongs to the original creator.
Because of this, the original creator has the exclusive right to prevent any third party from doing any of the following:

- Copying the original piece of work
- Present copies of the piece of work to the public
- Making an adaption of the original work

The one I have highlighted in bold is the one Soulslayer is currently breaching, as he is uploading pieces of copyrighted work onto a public website for others to download and edit further, breaching the copyright even more than it already has been.
So, I'm sorry to say Loose Crow, you and your fellow administrators on www.soulslayer-graal.info are indeed breaching copyright, and so you must remove the work.
If you want to keep doing this, please find every creator for each artwork you have uploaded and ask for their permission to do so, otherwise, like I said, you're breaching copyright.

Also, if you're a little skeptical about the whole "copyright on creation" idea, then just know that GraalOnline owns the images as they have been uploaded onto Graal with the owner's consent (in one way or another), and that they now own them.