Not to rain on anybody's parade, especially since it is obviously nice somebody attempts to provide a service to the MorphOS community, but...

If anybody uses artwork from third parties without an explicit or implicit permission, irregardless whether it is done to create a website, wallpapers, icons or whatever, one would at the very least expect the original creators (all of them) to be given proper credit.

While it is usually perfectly fine to modify graphics for your own personal use, your legal (as well as moral) responsibilities change once you start publishing and distributing the results of your modifications to the public.