This is what the Guerilla unit had to say on Playstation boards about Kotaku's claims on the newly released KZ2 images as doctored :-
"They are only the tiniest bit touched up. Short answer is yes. Long answer is that there was a little bit of colour-correction done and some minor polish, but nothing major. Still very close to reality and it looks better in motion in my opinion.
Seb Downie - QA Manager - Guerrilla Games "
Link to the newly released screenshots are posted as credit URL and in the Alternative section