Whether it's photoshopped or not, the portrayal of what it is with the hellish nature of cannibalism is wrong.
I wouldn't eat the dead. Why not? Firstly, anyone in their right minds wouldn't go somewhere unprepared in such an event where their are shortages of food. I'd bury the dead in his/her place of death.
If anyone knows how to survive in the wild, there are plenty of edible plants and animals. Only thing one needs to know is how to hunt, trap, gather, and farm.