National Geographic is one of the pillars of the nature photography community. As such, its staff members consistently have to trawl through thousands of photos sent in from their own photographers, from freelancers and other images for contests and features. They are vigilant in ensuring the veracity of the images they receive to ensure that fakes or frauds aren’t published. Luckily they have several techniques to filter out rogue images,which they’ve been good enough to divulge.

“In the digital age, when it’s easy to manipulate a photo,” says Susan Goldberg, Nat Geo’s Editor-in-Chief, “it’s harder than ever to ensure that the images we publish, whether on paper or on a screen, reflect the reality of what a photographer saw through his or her viewfinder.”

Goldberg’s words ring true. In 2010, the Nat Geo team were fooled by an entry to their ‘Your Shot’ series. The image sent in by William Lascelles, of a scruffy dog sitting on a lawn, had a set of fighter jets added to the background in Photoshop. It took multiple complaints after publishing before the forgery was acknowledged and the picture removed. This echoes a similar event from earlier this year when a Nikon photo contest winner’s picture had also been (poorly) edited to include a plane flying overhead. Even the very best in the industry can let manipulated images slip through the cracks.

Unlike that dreadful Nikon award entry, some edits are extremely difficult to spot. In those cases you have to go further than just examining it with your eyes. “You can’t always tell if a photo is fake,” explains Sarah Leen, director of photography at National Geographic, “at least not without a lot of forensic digging.”

This ‘digging’ involves getting information straight from the image files themselves. Nat Geo now has a stringent policy that everyone, even their own trusted photographers and stock image sources, is required to send in their raw image files. These contain data directly from the sensor of the digital camera that took them. This data is far less likely to have been played with and lends a certain level of authenticity.

But what happens when that raw file is simply not at hand? The answer is old-school interrogation. “If a raw file isn’t available,” says Goldberg, “we ask detailed questions about the photo. And, yes, sometimes what we learn leads us to reject it.”

“We ask detailed questions about the photo. And, yes, sometimes what we learn leads us to reject it.”

The issue isn’t just about major cuts and edits to pictures but even about slight changes in processing such as the lighting and contrast of a piece. Nat Geo editors are allowed to conduct minor changes to better reflect how the eye would perceive the captured image on site. However that can lead to some very subjective judgement calls. Goldberg uses the following example: “One of our photographers recently entered a photo in a contest. It was rejected as being over-processed; our editors, on the other hand, saw the same photo and thought it was OK.” Goldberg, whose team chose to publish the picture, says that it continue to be an ongoing discussion about who is “right” in situations like this.

Goldberg claims that National Geographic has maintained a strict adherence to authenticity ever since an embarrassing incident in 1982. A photograph of camels crossing in front of the pyramids of Giza at sundown was manipulated in order to better fit the print magazine’s vertical portrait alignment. This involved bunching up the pyramids from the horizontal landscape shot to fit together and was not received well.

“A deserved firestorm ensued,” Goldberg recalls, “‘National Geographic moves the pyramids!’ came the outcry.” Goldberg says it was that event that taught them the lesson, “At National Geographic, it’s never OK to alter a photo.”

Numerous high profile cases of photographers being accused of unethical manipulation have been in the news as of late. Even regular Nat Geo contributor Stephen McCurry has been called out on potential counterfeiting in his work. It is unsurprising that Goldberg is making the magazine’s message clear.

As Goldberg puts it,“making sure you see real images is just as important as making sure you read true words.”