Dying Princess Diana Photo Shown in New Documentary at Cannes Film Festival

"We're more comfortable looking at images of death when they are culturally distant or geographically distant. We weren't shown pictures of people who died in 9/11, but we were shown people who died in the 2004 tsunami," Zelizer said.

Zelizer said that technical advances in cameras and the advent of cell phone cameras have made capturing death photos easier.

Sept. 6, 1997: Princess Diana Funeral Watch Video

The Death of Princess Diana: Part 1 Watch Video

The Death of Princess Diana: Part 2 Watch Video

"We've seen people minutes before their death, the Pakistani Benazir Bhutto, John F. Kennedy...As cameras have gotten faster and lighter, the capacity for cameras to enter into situations involving death or near death has absolutely increased. Being able to show those pictures is not a question of technical capability, but much more a question of moral standard and political circumstance."

Zelizer said that displaying images of death or near death can actually help the public's healing process and understanding of an event. Since the film centers on Diana's death, showing those images makes sense, Zelizer said.

"Her death is absolutely part of the sequence of action that they're telling and when we leave that to the imagination, it takes on a magical power, it becomes greater than it is…we're actually giving it more power over us than if were we to actually look at it," said Zelizer.