Actually, if you generated the exact same picture yourself, it is not copyright infringement, but still copyrighted. It's one of those weird differences between copyright and patents. If you can show you produced the work independent of the other work, you are free of infringement claim. Same defense will not work in a patent case (although knowing infringement will usually get you a harsher penalty). Now of course, that's just theory, in practice that's an uphill battle to prove.
And also, you can copyright something that is a production of something that isn't copyrightable. For instance, individual words in the English language that are not copyrightable can end up copyrighted merely by being expressed in a set order (aka a work of literature). Same here. While every individual element of that nature shot isn't copyrightable, the picture itself is as it a particular arrangement of time, place and setting that is deemed artistic.