Davidson -- who runs a US$500,000-per-year business photographing objects in microscopic detail -- slid the exposed innards of a Silicon Graphics microprocessor under his hybrid camera-microscope.

Amid the city-street-like layout of the silicon chip, something caught Davidson's eye, like a building that didn't belong.

"I cranked up the magnification, and then I realized -- it was a little rendition of Waldo," Davidson said. "Two hundred microns (or 200 millionths of a meter) away, I found a rendition of Daffy Duck."

Each image had the altitude of a dust particle, between 10 and 30 microns high. Both had been printed, along with the processor's minuscule transistors, in that photographic moment when an engineer's design is born as silicon.

As Davidson has come to discover, the designers of printed circuits have been enhancing their intricate circuit-scapes for decades. The images -- from Waldo to the graphics in a personal wedding invitation -- are one way chip designers add ghosts to their machines.

The hidden image is created along with the rest of the image that is a printed circuit, just another line formation in the labyrinthine layout. The creative add-ons are simply fitted in where unused surface space is available.

"Some chips have quite a bit of [extra] room," Davidson says, silicon voids between a chip's memory registers and data caches. Many chips also have a signature area, normally used to identify the chip, its designers, and manufacturer.

Davidson has been hunting for hidden chip images since discovering the first one three years ago. As his online exhibit will tell you, he's spotted a hummingbird on a Hewlett-Packard RISC design, a California license plate on a MIPS 4000, and one of his oldest finds -- on a chip used in Macs circa 1988 -- the Sta-Puff Marshmallow Man (a protagonist in the movie, Ghostbusters).

The oldest known image appeared 20 years ago, when Mickey Mouse took silicon form on the chip of an early calculator.
"It's a passion," says MIPS spokeswoman Constance Sweeney, who confirms that the extra artistry is common among chip designers. "It's a way of putting a signature on their work.... After putting so much time and effort into a particular design, it's a means of personalizing it."

Few chip designers are vocal about the practice. And Davidson says it's not something every company encourages. Of the estimated 90,000 chip images Davidson has discovered, not one has turned up an Intel chip.

"Intel may be more stringent," he says. "Some companies say, 'That's not the kind of thing we do.' It's not real consistent."

Davidson has seen interest in the images surge since October, when he started to post them in his company's Web photo gallery. For a gallery that averages a thousand hits a day, Davidson says the chip section has lately gotten the greatest response.

The gallery features mega-magnified photographs from all areas of Davidson's work: from beer and Ben & Jerry's ice cream to vitamins and margaritas, pesticides and birthstones. The images have appeared on ties, as screen savers, and in custom photography for the pharmaceutical and microprocessor design industries.

"The hard part is capturing on film what you see in the microscope with the eye," Davidson says of his work. He's had to modify he way he processes color film -- enhancing color saturation and contrast -- so that the chip images show clearly.