Newsgroups: sci.image.processing
From: Steve@dstrip.demon.co.uk (Steve Rencontre)
Path: cantaloupe.srv.cs.cmu.edu!rochester!udel!gatech!howland.reston.ans.net!pipex!peernews.demon.co.uk!dstrip.demon.co.uk!Steve
Subject: Re: Image file formats and compression
References: <MXM.95Apr24110841@dcs.ed.ac.uk> <3niu6p$f4a@ed.petech.ac.za> <252339006wnr@dstrip.demon.co.uk> <aprc.218.0010F58A@pcmail.nerc-bas.ac.uk>
Organization: Datastrip Limited
Reply-To: Steve@dstrip.demon.co.uk
X-Newsreader: Newswin Alpha 0.7
Lines:  24
X-Posting-Host: dstrip.demon.co.uk
Date: Thu, 27 Apr 1995 15:14:09 +0000
Message-ID: <115971154wnr@dstrip.demon.co.uk>
Sender: usenet@demon.co.uk

In article: <aprc.218.0010F58A@pcmail.nerc-bas.ac.uk>  aprc@pcmail.nerc-bas.ac.uk (A P R Cooper) writes:

> SAR radar images are inherently quite noisy, with lots of speckle in the 
> image. However, the statistics of the speckle carry useful information! 
> Therefore, lossy algorithms are not suitable in cases where the noise in the 
> image may carry useful information.

Hmm... One could argue that if it contains real information, it's signal,
not noise, no matter what it might *look* like. I would then say that
this is not an 'image' in the conventional sense, and therefore I would
not expect human-visual-system-optimised algorithms to work well.

I can, however, envisage *in principle* a lossy compression algorithm which
would throw away only information of little or no significance in SAR terms.

Really, though, this is yet another instance of the general rule that 
you should know the applicability of tools before you use them :-)

-----------------------------------------------------------------------
Steve Rencontre               |  steve@dstrip.demon.co.uk (business) 
If it works, it's obsolete.   |  steveren@cix.compulink.co.uk (private)
-----------------------------------------------------------------------

