<br><font size=2 face="sans-serif">IMO:</font>
<br>
<br>
<br><font size=2 face="sans-serif">Michael,</font>
<br>
<br><font size=2 face="sans-serif">My concern as a custodian of significant
image resources is to ensure that the integrity of this data is protected
and available for future analytical use by ourselves and by the public.</font>
<br>
<br><font size=2 face="sans-serif">As an example, to conduct multi-temporal
analysis of 'imagery' to help understand big picture issues such as climate
change.</font>
<br>
<br>
<br>
<br>
<br><font size=2 face="sans-serif">I understand that wavelet compressions
such as MrSid and ecw are lossy compressions and JPEG 2000 can be 'lossless',
or as often occurs, lossy.</font>
<br>
<br>
<br>
<br><font size=2 face="sans-serif">I'm currently seeing proposals to the
effect:</font>
<br>
<br><font size=2 face="sans-serif">- wrt imagery, most people only want
to look at pretty pictures</font>
<br>
<br><font size=2 face="sans-serif">- therefore we'll compress our imagery
via wavelet compression and save a lot of disk space and ongoing SAN costs
by backing up the source imagery to tape. Noone uses it anyway.</font>
<br>
<br>
<br>
<br><font size=2 face="sans-serif">I've been around long enough to expect
problems from tape backups, and to not expect my data to be there when
I request a restore.</font>
<br>
<br><font size=2 face="sans-serif">I can also see an increasing need for
image analysis for big picture issues such as climate change and water
shortage (in Australia).</font>
<br>
<br>
<br><font size=2 face="sans-serif">Therefore, naiave as it is, I want to
be 'convinced' that our data is protected for future use before agreeing
to such potentially irreversible proposals.</font>
<br>
<br>
<br>
<br><font size=2 face="sans-serif">Bruce</font>
<br>
<br>
<br>
<br>
<br><font size=2><tt>discuss-bounces@lists.osgeo.org wrote on 24/02/2008
08:44:25 AM:<br>
<br>
> Bruce-</tt></font>
<br><font size=2><tt>> </tt></font>
<br><font size=2><tt>> It is not clear to me what sort of "study"
you would need to <br>
> convince you, as the ISO standard for encoding data into the <br>
> JPEG-2000 file format is by construction mathematically and <br>
> numerically lossless process. (Indeed, "compression",
i.e. throwing<br>
> away bits so as to further reduce storage requirements, is actually
<br>
> not defined within the scope of the standard.)</tt></font>
<br><font size=2><tt>> </tt></font>
<br><font size=2><tt>> -mpg</tt></font>
<br><font size=2><tt>> </tt></font>
<br><font size=2><tt><br>
</tt></font>
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