Spot the fake photo through photo forensics

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Trust in media is declining, particularly for online news and social media. And how can you tell which images are real, and which images are photoshopped? Duc Tien Dang Nguyen visited the ViSmedia Conference to demonstrate which methods researchers uses to detect visual disinformation. 

Images have been retouched for many reasons. An image of an Iranian missile test appeared on the front page of many newspapers, and went viral. It shows four missiles being launched. But one missile was added to conceal a missile on the ground that did not fire. The image came from Sepah News, the media arm of Iran’s Revolutionary Guards. 

Photoshopping is often used to make public figures look stronger, slimmer, and more elegant. We even have pictures that are completely generated from computer graphics, and are hard to tell from the real ones. At the same time, we have real photos that look photoshopped. 

In photo forensics we try to verify what is real and what is computer generated or photoshopped. A tampered photo is almost always created on the base of a real one, and every step leave some traces that forensics can use to review what happened when the light goes through the camera. As a first step, you can find the source of the photo through reverse image search. You can also look for the inconsistencies in the image, especially in lighting, shadow and reflection. And you can zoom in for the really small parts. 

There are also more advanced photo forensic tools, for example magnification to identify the noise from the photo sensors. But technology can only take us so far. If a fake video goes viral, often the damage is done before anyone even has the change to analyse the content. So slow down a bit before you share something. 

Thomas Wold