JBIG2 Feature: |
Benefit: |
Example: |
Higher compression rates than its predecessors (e.g., JBIG1,
TIFF G3, and G4). File size reduction capabilities up to 90%
or higher. |
Reduction in storage space and transmission bandwidth. |
With JBIG2 compression, a 78 MB uncompressed 500-page PDF
document, would see its file size drop to 12.7 MB. An
equivalent TIFF file would be approx. 15.8 MB. |
Lossy and lossless compression methods. |
Lossy yields a higher compression rate without any
perceivable information loss. |
A pass to clean the document of dots and artifacts from a
scanned document can help JBIG2 compression by coding more
simple white areas. |
The use of symbol dictionaries |
• For the compression of other images within the same
document .
• Eventually one symbol dictionary could be used to
recognize the text in the image. It contains the building
blocks of a possible OCR procedure to help rebuild font
information (if lost). |
• Unique to one PDF document, a global JBIG2 stream can
contain a dictionary of symbols used for all the pages of
the document.
• Once the dictionary is built, software attempts to
recognize letters and build legible text from them. |
The use of arithmetic and Huffman coding schemes for bit
representation. |
Huffman coding takes less page memory and has faster
compression and decompression than arithmetic coding.
However, arithmetic compression is slower, uses more memory
but yields better compression results. |
JBIG2 can support the Huffman and the arithmetic coding
algorithms for image structure information such as encoding
schemes, references, indexes, sizes, offsets, and popular
symbol identities. |
ITU-T T.6 facsimile coding schemes and coding control
functions for Group 4 facsimile functionalities which is
activated by a MMR (Modified Modified READ (Relative Element
Access Designate)) flag. |
Use of the latest facsimile logic for the compression of
building block images. |
Any image leaf can be coded using MMR logic. In addition, a
symbol in a dictionary or whole page can be found in the
JBIG2 stream as a MMR image. |
Stripped-page compression. |
JBIG2 can compress uninterrupted image flows. |
Under specific circumstances, if a scanner sends image
information without a page cut, a JBIG2 stream can still
take the data and compress it. |
Most PDF viewers support reading JBIG2 (ver. 1.4 and
higher). |
JBIG2 technology can be easily integrated into the PDF’s
established technologies. |
Most of the PDF documents produced by high-end scanners with
professional drivers are compressed with JBIG2 technologies. |