Section: ~DjVuLibre-3.5~ (1)
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bzz - DjVu general purpose compression utility.
bzz -e[blocksize] inputfile outputfile
bzz -d inputfile outputfile
The first form of the command line (option
compresses the data from file
and writes the compressed data into
The second form of the command line (option
and writes the output to
The optional argument
specifies the size of the input file blocks processed by the Burrows-Wheeler
transform expressed in kilobytes. The default block sizes is 2048
The maximal block size is 4096
Specifying a larger block size usually produces higher compression ratios
and increases the memory requirements of both the encoder and decoder.
It is useless to specify a block size that is larger than the
The Burrows-Wheeler transform is performed using a combination of the
Karp-Miller-Rosenberg and the Bentley-Sedgewick algorithms. This is comparable
to (Sadakane, DCC 98) with a slightly more flexible ranking scheme. Symbols
are then ordered according to a running estimate of their occurrence
frequencies. The symbol ranks are then coded using a simple fixed tree and
the ZP binary adaptive coder (Bottou, DCC 98).
The Burrows-Wheeler transform is also used in the well known compressor
The originality of
is the use of the ZP adaptive coder.
The adaptation noise can cost up to 5 percent in
file size, but this penalty is usually offset by the benefits of
The following table shows comparative results (in bits per character)
on the Canterbury Corpus (
). The very good
performance on the spreadsheet file
puts the weighted average ahead of much more sophisticated
compressors such as
| compress ||3.27 ||0.97 ||3.56 ||2.41 ||4.21 ||3.06 ||3.38 ||3.68 ||3.90 ||4.43 ||3.51 ||2.55 ||3.31 |
| gzip -9 ||2.85 ||0.82 ||2.24 ||1.63 ||2.67 ||2.71 ||3.23 ||2.59 ||2.65 ||3.31 ||3.12 ||2.08 ||2.53 |
| bzip2 -9 ||2.27 ||0.78 ||2.18 ||1.01 ||2.70 ||2.02 ||2.42 ||2.48 ||2.79 ||3.33 ||2.53 ||1.54 ||2.23 |
| ppmd ||2.31 ||0.99 ||2.11 ||1.08 ||2.68 ||2.19 ||2.48 ||2.38 ||2.43 ||3.00 ||2.53 ||1.65 ||2.20 |
| fsmx ||2.10 ||0.79 ||1.89 ||1.48 ||2.52 ||1.84 ||2.21 ||2.24 ||2.29 ||2.91 ||2.35 ||1.63 ||2.06 |
| bzz ||2.25 ||0.76 ||2.13 ||0.78 ||2.67 ||2.00 ||2.40 ||2.52 ||2.60 ||3.19 ||2.52 ||1.44 ||2.16 |
Note that DjVu contributors have several
entries in this table. Program
was written some time ago by Joe Orost.
is an improvement of the
method invented by Paul Howard.
was written by Léon Bottou <email@example.com
was then improved by Andrei Erofeev <firstname.lastname@example.org
>, Bill Riemers
> and many others.
- SEE ALSO
This document was created by
using the manual pages.
Time: 00:05:50 GMT, November 14, 2015