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LZW decompress. how to?

Posted on 1998-07-01
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I have a chunk of bytes LZW compressed. It's a part of a acrobat pdf file. I need to decompress that data to parse that postscript program.
Do you know any way to do that by MFC, or a dll/ocx lybrary (no matter price)?(All libs that I found, work with Tiff/lzw, and I have a plain chunk of bytes)
Help please.
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Question by:wau
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by:danny_pav
ID: 1318600
Will the functions in LZEXPAND.DLL help you?

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by:wau
ID: 1318601
Like VC++5.0 documentation sais, the Lzexpand.dll functions can only decompress Huffman, Run-Length and Lempel-Ziv methods. Anyway, I tried with LZOpenFile/LZRead/LZClose secuence, and nothing, I read garbage.
I think I need a dll that works with LZW buffer to buffer decompression.
Thanks.
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by:tdubroff
ID: 1318602
I think any 'LZ' type uncompression is relatively simplistic (at least compared to the compression algorithm).  It might be easy enough for you to do a search on the web for 'LZW' compression and decompression algorithms, and then design your own decompressor.
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by:duneram
ID: 1318603
here is something you could try.   Write the company (who makes acrobat) and offer to sign an NDA because you are writing something that would be both to their and your benefit.  If you do that, they would then be able to provide you with the layouts and probably decompression alg.

I know this will work if you approach it right, as I used this technique to develop a (internal to a company) ODBC driver for Lotus.   I just went straight to the company, signed an NDA and received several books describing all the information I needed to know.

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AlFa earned 40 total points
ID: 1318604
Try zlib (it's gzip from unix) you can find it at codeguru or something like that. it's also included in cimage.lib (source code is available).

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