There are two main ways to deal with the challenge of verifying images, explains [Hany] Farid [a computer science professor at Dartmouth College]. The first is to look for modifications in an image. Image forensics experts use computational techniques to pick out whether any pixels or metadata seem altered. They can look for shadows or reflections that don’t follow the laws of physics, for example, or check how many times an image file has been compressed to determine whether it has been saved multiple times.
The second and newer method is to verify an image’s integrity the moment it is taken. This involves performing dozens of checks to make sure the photographer isn’t trying to spoof the device’s location data and time stamp. Do the camera’s coordinates, time zone, and altitude and nearby Wi-Fi networks all corroborate each other? Does the light in the image refract as it would for a three-dimensional scene? Or is someone taking a picture of another two-dimensional photo?
Two startups, US-based Truepic (which Farid consults for) and UK-based Serelay, are now working to commercialize this idea. They have taken similar approaches: each has free iOS and Android camera apps that use proprietary algorithms to automatically verify photos when taken. If an image goes viral, it can be compared against the original to check whether it has retained its integrity.
Learn More, Direct to the Serelay Website