An imaging technique used to enhance ancient engravings might soon help you erase rips and creases from old photographs, using an ordinary flatbed scanner.
Tom Malzbender of Hewlett-Packard Laboratories in Palo Alto, California, and his colleagues pioneered a method of taking scores of digital photographs of a textured object from slightly different angles to create a computer model of the object's bumps and ridges. The team used it to bring carvings on previously unreadable ancient tablets into sharp relief. But back then the technique involved a metre-wide plastic dome and 50 separate light sources.
Now Malzbender's team has achieved the same effect using an off-the-shelf flatbed scanner. They rely on the fact that modern scanners use two separate light bulbs. This feature was added to scanners to improve colour quality, but it also lets you capture the image from two different angles. Re-scanning the object after rotating it 90 degrees provides a total of four different angles, more than enough to deduce 3D information about the object - mathematically, you only need three.
To fix old, damaged photographs, the software flags every pixel in the scanned image that isn't lying flat against the scanner, an indication that there is a tear or a fold there. Then it automatically replaces those pixels by copying adjacent ones, smoothing over the damaged region.
Hewlett-Packard has no immediate plans to release the software commercially, but "anybody with good programming skills could implement this", says Malzbender. "It would take them a while, it's not a slam dunk, but they could do it."
"The premise seems promising," says Bob Kolarik, a professional photograph restorer whose company, Yesteryear Memories, is based in Bolingbrook, Illinois. "If I can reduce the amount of time spent on a restoration project, I would probably go for it."
First published on NewScientist.com