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computers / comp.compression / Re: PPM 8-bit?

SubjectAuthor
* PPM 8-bit?Harry Potter
+- Re: PPM 8-bit?Harry Potter
`* Re: PPM 8-bit?Shelwien
 `- Re: PPM 8-bit?Harry Potter

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Subject: PPM 8-bit?
From: Harry Potter
Newsgroups: comp.compression
Date: Mon, 25 May 2020 23:45 UTC
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Date: Mon, 25 May 2020 16:45:27 -0700 (PDT)
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Subject: PPM 8-bit?
From: rose.jos...@yahoo.com (Harry Potter)
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Hi!  I just looked at the Wikipedia article "Prediction by partial matching" and like what I hear.  I believe I get the gist of it: shorten each character to the likelihood that it will occur after the previous character.  Now, I have an idea to shorten the code:

1.  Scan the input for all strings and count the number of occurrences of each character after the last.
2.  Scan the occurrences and write, for each preceding character, the 16 most-often-occurring following characters. 16 could be any useful number.
3.  Scan the input again and, for each character stored as likely-occurring, write 1 then the shortened count.  Otherwise, write 0 then a fraction of the entry skipping the stored values over the total non-stored values.  I have a way to shorten these values in bit streams.

Now, this requires a lot of memory: the counts alone would require 256k and, therefore, I deem it a 32-bit technique.  I am currently working on 8- and 16-bit compression technique.  I plan to do 32- and 64-bit compression at a later date.  Unless, of course, I can shorten the buffer to include only the often-occurring values.  :)

What do you think?


Subject: Re: PPM 8-bit?
From: Harry Potter
Newsgroups: comp.compression
Date: Tue, 26 May 2020 19:07 UTC
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Subject: Re: PPM 8-bit?
From: rose.jos...@yahoo.com (Harry Potter)
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I successfully implemented an 8-bit version of PPM based on my interpretation of PPM, and it backfired on me.  :(


Subject: Re: PPM 8-bit?
From: Shelwien
Newsgroups: comp.compression
Date: Tue, 26 May 2020 20:19 UTC
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Subject: Re: PPM 8-bit?
From: shelw...@gmail.com (Shelwien)
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It sounds like this: https://en.wikipedia.org/wiki/Burrows%E2%80%93Wheeler_transform


Subject: Re: PPM 8-bit?
From: Harry Potter
Newsgroups: comp.compression
Date: Thu, 28 May 2020 20:22 UTC
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Subject: Re: PPM 8-bit?
From: rose.jos...@yahoo.com (Harry Potter)
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I tried my rendition of PPM, but it didn't work.  :(

On Tuesday, May 26, 2020 at 4:19:46 PM UTC-4, Shelwien wrote:
It sounds like this: https://en.wikipedia.org/wiki/Burrows%E2%80%93Wheeler_transform

Tried that, too.  It didn't work, either. :(


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