For a while, I was publishing a semi-regular feature in this blog entitled “Truthful Photo Editing,” in which I described how best to approach the editing features in tools like Photoshop so as to maintain the original truth of a photo. One of the recurring themes of those posts is that there are, unfortunately, few firm rules about what tools and techniques are acceptable in a truthful workflow. Almost any tool can be used both sparingly in ways that enhance and severely in ways that distort, and what level of truth must be maintained is dependent on context. The type of editing permissible in photojournalism differs from what is permissible in a legal setting or in a medical image. Ultimately there is no substitute for good judgment. But applying good judgment is hard, especially when the baseline of truth you’re comparing against is itself open to interpretation.
Welcome to the Fourandsix blog, where you’ll find tips on image forensics techniques and commentary on issues relevant to photo tampering and the responsible use of imaging tools.
This week, a controversy regarding this year’s winner of the World Press Photo contest came to a head. Since the contest winner was announced earlier this year, there have been concerns that the photo looked a little too unreal and even cinematic to be an authentic photo. Those concerns reached a new level this week when the Hacker Factor blog posted evidence which it claimed showed that the award-winning photo was in fact a composite of multiple images. After this claim blew up further on the Extreme Tech website, Fourandsix was enlisted by World Press Photo to help settle the issue. We provided our own analysis refuting the other evidence, and demonstrating that the photo is not a composite but rather a single photo to which adjustments have been applied to selective regions.
I was recently talking to my friend and colleague Prof. Michael Black about a seemingly unlikely image of President Obama and Vice President Biden putting on the White House lawn. We were discussing how a shadow and lighting analysis could be applied to this image to determine if it is fake. Michael made the clever observation that the President’s left ear provides further information about the lighting in the scene.
A while back I described how optical flare is sometimes misinterpreted as evidence of other-worldly beings. Optical flare occurs when stray light enters the camera and is scattered throughout the optical train before striking the camera sensor. In addition to creating cool visual effects, optical flare can be used to determine the location of the light in the image.
To create a convincing composite, it is often necessary to stretch or rotate portions of an image. For example, when creating a photo of a giant hog, cat, rabbit, fish, etc., the critter may be resized in order to exaggerate its size. This process introduces specific correlations in the image. Because these correlations are unlikely to occur naturally, their presence can be used to detect this specific type of manipulation.