THEORY AND PRACTICE

JPEG 2000: The Next Big Thing?

by Lowell Rapaport

How do companies share document images over the Internet? They either render non-browser-viewable images on the fly into file formats that browsers can understand, or they install plug-ins, applets or Active X controls to support browser-based viewing.

Both methods have drawbacks. Server-side rendering requires beefier servers or server clusters, while client-side viewers and plug-ins can be expensive and complicated to deploy. Converting or saving images in PDF format is a popular third alternative, but this requires the Acrobat Reader viewer, and many complain that PDF images are bandwidth hungry.

Enter JPEG 2000, a new image compression codec and format. JPEG 2000 uses wavelet compression, a technology that is more efficient than the original JPEG and that presents fewer objectionable compression artifacts.

For document imaging use, the interesting component of JPEG 2000 is Part VI of the specification, which has at least another year to go before it is likely to be adopted as a standard. (Standards bodies that will review the format include the International Organization for Standardization and International Telecommunication Union.)

Part VI defines a special version of JPEG 2000, dubbed JPM, that will allow images to be compressed using as many as four codecs: Group 4, JBIG II, JPEG or JPEG 2000. This means you can compress an image using JPEG on the photographic portions and Group 4 or JBIG II on the bitonal text and line art, thereby reducing the file size dramatically. These four different codecs can coexist within the same image; the appropriate combinations can be selected automatically by the compression engine.

Louis Sharpe, president of Picture Elements and one of the co-editors of the Part VI spec says the idea was to get document imaging into the mainstream. "Part VI of JPEG 2000 will put native Group 4 compression in the Web browser," he says. "Instead of having to install multiple document viewing clients in large companies, every desktop in the world will be able to view these images."

That's assuming JPEG 2000 gets native support from Web browsers, something that's not a sure thing. "The JPEG 2000 file format is not finalized yet," Microsoft stated in response to our questions. "We currently do not have plans to natively support JPEG 2000 in any upcoming products; when JPEG 2000 is ratified, Microsoft will re-evaluate future support."

Even if it is adopted as a "standard," JPEG 2000 will need more than Microsoft's support to ensure adoption. The PNG (portable network graphics) file format was intended to replace GIF (graphics interchange format), but it hit the market with a resounding thud despite support in both Internet Explorer and Netscape Communicator. Working in JPEG 2000's favor is the imprimatur of the Joint Photographic Experts Group and the fact that it is a free, open standard. Only time will tell if it succeeds.