By Andrew Curry

In the iconic image, Lenin stands alone atop a wooden dais, speaking to a rapt crowd filling the square in front of Moscow's Bolshoi Theater. But someone is missing. When the photograph was first taken in 1920, Lenin's comrade Leon Trotsky stood nearby. Seven years later, power struggles forced the revolutionary from the Soviet Communist Party–and so a photo retoucher meticulously painted him out of the picture.

The Soviet impulse to alter images isn't anything new. In ancient Rome, the Senate wiped its deposed emperors from the historical record by a decree of damnatio memoriae (condemnation of the memory), removing their names from public inscriptions and destroying their statues. A century ago, one common con was a "spirit photograph" with the floating faces of deceased relatives. The pictures were really double exposures. The famous Cottingley fairies hoax, perpetrated by two Victorian teens posing with paper fairy cutouts, took decades to discredit.

But the most dramatic and damaging examples of alteration probably come from Joseph Stalin's Soviet Union. With paint, razors, and airbrushes, Soviet graphic artists and censors erased the memory of the party's enemies by removing the faces of purged leaders and party officials from photographs. "The physical eradication of Stalin's political opponents at the hands of the secret police was swiftly followed by their obliteration from all forms of pictorial existence," writes David King in his pictorial history, The Commissar Vanishes.

Part of Stalin's legacy was an industry of photo fakers who became active in the Cold War battle over public opinion. In the 1950s and '60s the CIA began to focus on a flood of altered photos coming from the Soviet bloc, hoping to glean information about Communist leaders and military capabilities–and to sift out and discredit pictures that were faked for propaganda purposes. A top priority was to determine who was in and who was out from changing images of public appearances, as photo manipulators moved certain leaders to the periphery. Analysts also revealed that photos of Soviet industrial and military prowess were often just retouched pictures of American factories, with workers clumsily disguised in different clothes.

Today, computers have made the job of altering photos easier. "[Computers] are destroying the credibility of photography, and it's getting worse," says Dino Brugioni, a retired CIA photo analyst and the author of Photo Fakery: The History and Techniques of Photographic Deception and Manipulation. Examples are often subtle. Newsweek straightened the teeth of septuplets mom Bobbi McCaughey in a cover photo. National Geographic has shifted photo elements for a cover shot, once moving the Great Pyramids electronically so they'd line up in a row for a 1992 cover. Editors defend the changes, which they say are made for the sake of artistic purposes or heightened effect.

Though the media are the most visible culprit, it is the courtroom that may face the most profound changes from the rise of digital photography. With basic computer programs and limited skills, crucial details can be deleted or added–incriminating skid marks removed from pictures of an accident, bruises added to pictures of an assault victim. Accustomed to presenting pictures as indisputable evidence at trial, "judges and lawyers are still back in the Stone Age," Brugioni says. "Photography shouldn't be accepted as prima facie evidence in court any longer–digital cameras can erase the evidence." After all, a modern mouse is much easier to wield than a Roman chisel.