(PPMII) Resources required for Information Inheritance
george
improvement in the Current Compression ratio I would like to implement
PPMII.
For this I have read the paper "PM: One step to Practicality, Dinitry
Shkarin" and it was difficult to grasp the concept and implementation
approach of the algorithm.
Any other resource on the web, which will provide the clear picture in
understanding this algorithm and its implementation, will be
appreciated.
George Wilson
Matt Mahoney
Charles Bloom wrote a paper on PPMZ, which uses some of the same ideas,
so it might help in understanding. http://www.cbloom.com/src/ppmz.html
I believe PPMZ is one of the codecs used in Malcolm Taylor's WinRK.
Dmitry Shkarin is the author of PPMd, PPmonstr, PPMs, and durilca.
Google for these.
The classic paper "Modeling for Text Compression" by Bell, Witten and
Cleary is a good introduction to PPM (and LZ), but you have probably
already seen it.
http://pharos.cpsc.ucalgary.ca/Dienst/UI/2.0/Describe/ncstrl.ucalgary_cs/1988-327-39
-- Matt Mahoney
Sachin Garg
I agree that paper you mentioned is a bit difficult to grasp and to
make matters worse, the code doesnt exactly does what is mentioned in
the paper. Probably because the code has undergone a couple of
revisions after the paper was published.
I had also tried searching for additional references but couldnt find
any, but after going through that paper a couple of times was able to
grasp most of it, Just ignore the maths and concentrate on results and
conclusions.
The code is written for maximum speed so its very cryptic to read. And
the author had an additional itch to make it fit into minimum number
of lines. But I doubt if any other PPM implementation can match its
speed.
I suggest going through ppmz first, that will make it easier to
understand ppmii concepts. Here is one reference which you *might*
find helpful but it just might confuse you a bit more.
http://www.muq.org/~cynbe/compression/ppmz2-vs-ppmd.html
Best of luck :-)
Sachin Garg [India]
http://www.geocities.com/schngrg
Dmitry Shkarin
>
> http://www.muq.org/~cynbe/compression/ppmz2-vs-ppmd.html
Excellent detective novel, similar to Conan Doyle's ones... ;-)