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Date: Thu, 5 Jul 2007 12:29:52 -0700
To: "Joris" <joris.at.lebbeke@skynet.be>
From: Stephen Carlsen <stcarlse@adobe.com>
Subject: Re: [Tiff] 16-Bit-Per-Channel Lossless Compression
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Status:   

Joris et al,

Indeed, so in my compression tests I used single-row tiles. This may 
not be optimal for all applications, but it is where I get the best 
import and display performance with page layout programs, and, 
amazingly, my compression ratios were about the same as when I tried 
more-square tiles.

YMMV, of course...

Best regards,
Stephen


At 8:30 PM +0200 7/5/07, Joris wrote:
>Stephen,
>
>Stephen Carlsen wrote:
>>Separating 16-bit data into byte planes before compressing seems to
>>be very effective. I get 40,882,548 bytes using the simple approach
>>of applying LZW (with predictor) to the high byte plane and no
>>compression on the low one.
>
>The problem here is that it is no longer sequential, i.e. a decoder 
>or encoder can no longer stream out line/block by line/block (where 
>block is a very limited chunk of compressed data, as line is a 
>minimal chunk of image), whilst streaming in the data as needed 
>block/line by block/line, and maintaining only a mimimal buffer in 
>between. Instead, total buffering of complete striles becomes 
>necessary in this scheme. Therefore, it doesn't scale well (problem 
>with LibTiff approach and huge striles), or doesn't stream well 
>(problem with minimal buffering maximum throughput approach of 
>AsTiff).
>
>
>Best regards,
>
>Joris Van Damme
>info@awaresystems.be
>http://www.awaresystems.be/
>Download your free TIFF tag viewer for windows here:
>http://www.awaresystems.be/imaging/tiff/astifftagviewer.html
>_______________________________________________
>Tiff mailing list: Tiff@lists.maptools.org
>http://lists.maptools.org/mailman/listinfo/tiff
>http://www.remotesensing.org/libtiff/

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