Legal Question in Intellectual Property in Oklahoma

Yes. Copyright protection is automatic upon creation of an artistic work. If you take the photo and "slightly modify" it, you have produced a derivative work. If you did not get permission to do that, you are hanging out legally as a copyright infringer, so you might want to check into the damages for copyright infringement before you infringe in this way. Perhaps the photographer won't care, but perhaps they will. Perhaps they never got a registration for their copyright, perhaps they did or will. You should see a copyright lawyer so you can get some advice, rather than admitting on lawguru your intent to engage in deliberate and willful infringement.