In the case of the photo at the top of this page, "the manipulations don't seem to have been done to significantly alter the photo's informational content," says Thuillier. There are no extra bodies or militants added by Photoshop. AFP therefore published the photo, along with a warning alerting clients to possible retouches and adding clearly that this was a photo pulled from the Internet, making it impossible to independently verify the date and location of the image.
"Of course, Tungstene can't detect photos that have been wholly staged," adds Thuillier. "If the jihadists had decided to pile bodies here from another location, or even if people are lying on the floor and pretending to be dead to make the scene more terrifying, the software can't detect that."
But the likelihood of this being staged is low, says Baz. Considering the type of violence known to have been perpetrated by ISIL over recent months in Iraq and Syria, it seems more likely that this was a real event.
"The jihadists don't need to stage incidents," says the photographer, who has covered conflicts in the Middle East and elsewhere for nearly 30 years.