PDF Adaptive Compression edges close to DjVu
a news report by PlanetDjVu, July 17, 2003
When Acrobat 6.0 was released last month, Adobe introduced the Version 1.5 upgrade to the PDF format, new JBIG2 and JPEG2000 compression methods, and a new image segmentation method called "Adaptive Compression".
JBIG2 is a new open standard for bitonal image compression, similar to the JB2 compression used in DjVu, and JPEG2000 is a new open standard for color and grayscale image compression, similar to the IW44 compression of DjVu.
Adaptive Compression is a method of segmenting color and grayscale images into foreground and background layers, just like the segmenter that is at the core of the commercial DjVu products from LizardTech. Unlike the DjVu segmenter, Adaptive Compression does not (yet) write color information into the image mask, but otherwise it is remarkably similar.
We are presenting here a comparison of DjVu with the new, Adaptive Compression PDF files. To view these PDF files, you will need either the free Acrobat Reader 6.0, or the full version of Acrobat 6.0. Previous versions of Acrobat Reader do not support the new compression methods, so they cannot decode and display these files. Note that while Acrobat 5.0 supports JBIG2, it does not support JPEG2000.
The sample files in this comparision are taken from the Transactions of the Bristol and Gloucestershire Archaeological Society website.
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