April 2004

Unpacking Pixels

A new bandwidth-conserving technique transmits different parts of a digital image separately, at different resolutions.

By Technology Review

Until Internet connections have infinite bandwidth, big digital files like color images will have to be compressed-which means a loss of detail. But Xerox researcher Robert R. Buckley has come up with a way to compress and transmit different parts of a digital image separately. People viewing the image online could conserve bandwidth by starting with a low-resolution preview but could selectively download portions of the image at higher resolution, showing specific details such as text or a face. Buckley's technique, which is part of the industry's new image compression standard, divides elements such as text and pictures into separate groups, each of which is saved using the best-suited compression method. (Text, for instance, needs to retain its sharp edges, while many photos don't.) The groups can then be downloaded individually, on demand. Xerox plans to license the concept royalty-free to companies developing image-editing software.