Just days after Sarah Palin’s selection last August as the Republican vice presidential candidate, a photo of a bikini-clad, gun-toting Palin blitzed across the Internet. Almost as quickly, it was revealed as a hoax—a crude bit of Photoshop manipulation created by splicing an image of the Alaska governor’s head onto someone else’s body. From start to finish, the doctoring probably took no more than 15 minutes.
Altering digital imagery is now ubiquitous. People have come to expect it in the fashion and entertainment world, where airbrushing blemishes and wrinkles away is routine. And anyone surfing the Web is routinely subjected to crude photographic mashups like the Palin hoax, whose creators clearly aren’t interested in realism but in whatever titillation or outrage they can generate.
But other photo manipulations demonstrate just how difficult it has become to tell altered images from the real thing. For example, in 2005 Hwang Woo-Suk, a South Korean professor, published a paper in one of the most prestigious scientific journals, Science, claiming groundbreaking advances in stem-cell research. But at least 9 of the 11 uniquely tailored lines of stem cells that Hwang claimed to have made were fakes. Much of the evidence for those 9 lines of stem cells involved doctored photographs.
Apparently, Hwang’s fabrication was not an isolated occurrence. Mike Rossner, then the managing editor of The Journal of Cell Biology, estimated that 20 percent of the manuscripts his journal accepted contained at least one image that had been inappropriately manipulated. Since then, a number of scholarly journals have implemented new fraud-detection procedures, such as software that makes it easier to compare images within or between documents. The incidence of image fraud in scholarly publishing has not declined, though; indeed, it seems to be on the rise.
A more recent example of photo tampering came to light in July 2008. Sepah News, the media arm of Iran’s Revolutionary Guard, celebrated the country’s military prowess by releasing a photo showing the simultaneous launch of four missiles. But one of those missiles had, in fact, failed to launch. The truth emerged after Sepah circulated the original photo showing three missiles in flight—but not before the faked image appeared on the front pages of the Chicago Tribune, the Financial Times, and the Los Angeles Times. If the world could be fooled by such a photo, then what’s to prevent any country or militant group from using doctored images to intimidate?
To be sure, photographic alterations have existed about as long as photography itself. But before the digital age, such deceptions required mastery of complex and time-consuming darkroom techniques. Today anyone with a modicum of computer skills can call on powerful and inexpensive software to alter digital images. And as sophisticated forgeries appear with alarming frequency, people’s belief in what they see has been eroded.
Over the past few years, the field of digital-image forensics has emerged to combat this growing problem and return some level of trust in photographs. By using computer methods to look at the underlying patterns of pixels that make up a digital image, specialists can detect the often-subtle signatures of manipulated images that are invisible to the naked eye.