World's biggest digital pic

A group of Dutch engineers has produced the world's largest known digital photograph--a 7.5GB monster that consists of almost 2.5 billion pixels.

The Netherlands Organization for Applied Scientific Research (TNO), a research and engineering conglomerate involved in fields ranging from aerospace to petroleum, announced the creation in a posting on the group's Web site Tuesday. The site includes a condensed version of the photo and a Flash-based application for viewing details.

The photo--an aerial image of the city of Delft that's unlikely to spur a sudden upswing in tourism there--consists of 600 individual images shot over the course of more than an hour. The images were then stitched together on a computer.

"It took about 24 hours to compare the overlapping photos and optimize them," according to the TNO statement. "Stitching the photos into one image required the capacity of five high-end PCs for three full days."

The image consists of precisely 2.487 billion pixels and would measure about 22 feet by 8.7 feet if printed at a standard resolution of 300 dots per inch. By contrast, typical consumer digital cameras capture images with 3 million to 5 million pixels.

The TNO team had to write its own software for much of the image-stitching work, including devising a new file format. The TIF format typically used for high-definition photos maxes out at 4GB. The group also solved temporary storage issues by creating a FireWire link between the camera and a laptop PC to capture images, bypassing the camera's memory card.

The TNO engineers pay credit to the previous record holder, photographer Max Lyons, who broke the 1 billion pixels mark last year with his panoramic image of Utah's Bryce Canyon National Park.