A New Web Image Format

MrP- writes: "BetaNews is reporting that a company called LizardTech has developed a new image format for the Web called DjVu." Apparently, it differentiates between forground and background components of an image, and compresses each appropriately. Good idea, but I'm skeptical of improvements (especially because they say it's "20 times faster then gifs" -- which measure compression in terms of speed? And they also say it compresses faster then pdf, but pdf isn't really an image format). No Linux support. And I don't see any source code on the format, so don't expect it to get a lot of support on any major Web sites, regardless of the compression.

Comments

Re:Some facts off the top of my head...

[Anonymous Coward]

Gary got is mostly right.

I am one of the four persons who created DjVu in the first place. The events took place in AT&T-Labs Research between 1997 and 1999.

1. There is Linux support. Just go to the download page and select the Linux platform. Most of DjVu was first coded under Linux.
2. After the Lizardtech deal, we set up a "non commercial site" named DjVuZone. It contains general information, benchmarks. links, a searchable digital library, etc.
3. There is source code. Lizardtech recently had the good idea to relicense version 2 of the DjVu reference library under the GPL. We have the corresponding online documentation on DjVuZone. We are just waiting for the release of version 3 to redo that part of the site.
4. DjVu combines several new technologies including new approaches to arithmetic coding (Z'-coder), new compression methods for textual images (Soft pattern matching, JB2), new wavelet method (IW44), and new ways of combining them together. The current implementation is geared toward compressing scanned document images in 24 bit colors around 300 dpi (raw size is 25MB) and typically packs them into 50-60KB. Neither TIFF, nor JPEG, nor JPEG-2000 nor Fax-G4 can do that. None of these technologies will let you realistically view such documents over the web. DjVu can.

Hope this helps :-).

- Leon Bottou, AT&T-Labs Research.

Actually quite an old product

[Nailer]

DjVu has been around for 2 years, and isn't anything new. In fact, it wasn't actually designed by Lizardtech - it was developed as an Open Source technology in the Olivetti and Oracle Researtch labs in Camridge, UK, and was sold when US telco AT&T purcahsed the labs.

Hence the Open Source products generally only seem to be there to satisfy existing licensing requirements from prior to Lizardtech's purchase. It's doubtful Lizardtech tend to encorage that aspect of the technology, and they're only promoting the closed source stuff.

However, the compression is indeed very real and the cross platform nature makes it quite useful for archiving stuff that won't be modified frequently in the future - remeber, that text ain't vectorized, it's just another layered image, AFAICT.

Re:Actually quite an old product

[dkh2]

True. If you want to see DjVu in action, go get the plugin at djvu.com and visit one of my projects here at CWRU. http://www.cwru.edu/UL/DigiLib/Hours/homepage.html

Picture this: Start with a 15th century Flemish "Book of Hours", hand illuminated on vellum (goat skin). Scan it at 600dpi 24bit for archival purposes. Reduce your tiffs to 300dpi and you still have 1.06 GB of image data (not very downloadable). Using the DjVu compressor we achieved 205:1 compression so the final product totals 5.44MB. By separating the pages so they only download when called for the initial download is a mere 45.06KB (including all of the HTML and other images on the page) with an average download of subsequent pages only 21.34KB.

DjVu was developed by AT&T Research. It was then purchased by LizardTech last year.

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