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From: "Joris" <joris.at.lebbeke@skynet.be>
To: "Andrey Kiselev" <dron@ak4719.spb.edu>,
        "Stephen Carlsen" <sc42business@mac.com>
References: <03cf01c7be60$7dc4b610$da60fea9@EKAT><p0624081ec2b189c30c42@[10.0.1.8]><20070705105619.GA13773@ak4719.spb.edu>
	<p06240828c2b2d975ba22@[10.0.1.8]>
Subject: Re: [Tiff] 16-Bit-Per-Channel Lossless Compression
Date: Thu, 5 Jul 2007 20:30:00 +0200
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Status:   

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
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