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Date: Fri, 23 Sep 2005 15:20:33 -0700
To: TIFF <tiff@lists.maptools.org>
From: Chris Cox <ccox@adobe.com>
Subject: Re: [Tiff] Additional Lossless Compression Schemes
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Status:   

At 5:11 PM -0400 9/23/05, Frank Warmerdam wrote:
>Folks,
>
>I was wondering if there is much interest in adding more lossless
>compression schemes in libtiff.
>
>In addition to Packbits (pretty crappy) we have LZW and the more
>recent Deflate.  My understanding is that Deflate is usually better than
>the old LZW though not as widely supported.  Also, that Deflate
>is essentially the "zip" compression type.

Yes, yes, and yes.


>Since then I have seen "gzip" on Unix, but I am not clear if that
>is just deflate or not.
>
>Then came bzip2 which seem 5-10% better in that gzip on many
>datasets.

Since TIFF supports predictors, it can already do better than straight deflate.



>Now looking around a bit I see LZMA which I have heard good things
>about.
>
>    http://www.7-zip.org/sdk.html
>
>Are there any opinions on possibly incorporating LZMA as an
>additional compression type?

Possibly - but it'll take a while to check the legal implications, 
get a couple of implementations going for cross testing, etc.

And I'd expect it to be at least 10% better than deflate to be worth 
the effort...

Chris
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