When can a photo be trusted?

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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.

Tuesday
Oct012013

Is That A Race Horse On The Roof?

When the owners of “Must Win” received a photo of their race horse on the roof of their home they were suspicious that it was a prank. A shadow analysis confirms that the photo is probably real.

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Tuesday
Sep242013

Why Did The Salmon Cross The Road?

In Southcentral Alaska, a brown bear runs runs through a crowd of people with a salmon in her mouth. The series of three photos is pretty remarkable and offers a good lesson in the physics and geometry of shadow formation.

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Tuesday
Sep172013

The Photojournalism "Darkroom" Then and Now

Last week, several of my photography friends were posting links to an article profiling Pablo Inirio, a darkroom master of the famed Magnum Photos photography cooperative, who has worked on some of the most famous images in photographic history. What makes the article most interesting are the before and after images of several iconic prints featuring such people as Audrey Hepburn, James Dean, and Muhammad Ali. The “before” images are heavily marked up by Inirio’s pen, indicating how he planned to dodge and burn various regions of the photo to accentuate important details and increase the impact of each shot. Though, of course, no details were added or removed in this process, the differences between the before’s and after’s is in some cases striking.

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Monday
Sep092013

Has My Real Life Been Photoshopped?

I was on my deck the other day reading a magazine. With the sun in front of me, the magazine was casting a shadow onto my chest. At the same time there was another shadow running in the other direction onto my lap. There is no light source on my deck or surrounding area, so I was baffled by this extra shadow. It took a few minutes of looking around to finally understand the source of this extra shadow.

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Tuesday
Sep032013

As Pretty (and Flat) as a Postcard

Last week we saw reports that Hong Kong’s tourism industry created giant fake skyline banners so that tourists can capture photographs of a clear skyline even on hazy days. Detecting this type of staged image poses a unique set of challenges. Given only a single image, it is difficult to distinguish between a well created backdrop and the real thing. But, from a pair of images, and with the help of a little projective geometry, we can tell the difference.

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