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