Grainy images of a large snake in Borneo's Baleh River have some locals afraid the mythical Nabu snake is back. Is Borneo's 100-foot river snake—reported yesterday by London's Telegraph and captured in photographs (one appears to the left)—real?

Like the Loch Ness Monster, countless UFOs and Bigfoot, it's hard to say, says Hany Farid, a computer science professor at Dartmouth University, because it's been captured in such low resolution. "It's as if you took a blood sample," he says, "threw away 99 percent of it and asked me to do a forensic analysis."

An expert of digital photography forensics, Farid notes that with so few pixels to analyze, there's much less evidence to weigh in one way or the other. At a high resolution—say, 1,000 by 1,000 pixels—tampering gets tougher. At that level, he says, "It's really hard to do. You've got to get it all just right."

The low level of resolution is precisely why viewers should be skeptical. To make a fraudulent photo, he says, one would want to work in high resolution, fake it as cleanly as possible and then compress it and make it a bit blurry. "That's a good way of masking any artifacts that you've left behind," he says.

Plus, Farid notes that although the fuzziness of UFO and Nessie photos might add a bit of desirable mystique, in this day and age of high-quality point-and-shoot digital cameras, there really aren't many reasons why anyone's daytime photos should be as blurry as those of the Borneo "snake."

In addition to the resolution of the two snake photos, other characteristics of an easy fake pop up as well, he observes. Both images show the snake in a somewhat open area, not interacting with other objects. It would be a lot more difficult, Farid says, to fake a snake wrapped around a person.  

Although Farid won't opine whether the Borneo photos are real or manipulated, he suggests a handy rule of thumb: "When you look at images, you should think about, 'How hard would this be to do?'"