[OSGeo-Discuss] 'lossless' JPEG2000

[Michael P. Gerlek]

Bruce-
 
Again, I'm not sure how to convince you of this...  JP2 is inherently
lossless just like GeoTIFF is; what arguments do you / would you find
persuaive to use GeoTIFF?  (alternatively, what do you use now that you
trust?)
 
[feel free to take this to private email, this is probably a bit
esoteric for the rest of the OSGeo crowd]
 
-mpg
 


________________________________

	From: discuss-bounces at lists.osgeo.org
[mailto:discuss-bounces at lists.osgeo.org] On Behalf Of
Bruce.Bannerman at dpi.vic.gov.au
	Sent: Saturday, February 23, 2008 2:19 PM
	To: OSGeo Discussions
	Subject: RE: [OSGeo-Discuss] 'lossless' JPEG2000
	
	

	IMO: 
	
	
	Michael, 
	
	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. 
	
	As an example, to conduct multi-temporal analysis of 'imagery'
to help understand big picture issues such as climate change. 
	
	
	
	
	I understand that wavelet compressions such as MrSid and ecw are
lossy compressions and JPEG 2000 can be 'lossless', or as often occurs,
lossy. 
	
	
	
	I'm currently seeing proposals to the effect: 
	
	- wrt imagery, most people only want to look at pretty pictures 
	
	- 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. 
	
	
	
	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.

	
	I can also see an increasing need for image analysis for big
picture issues such as climate change and water shortage (in Australia).

	
	
	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. 
	
	
	
	Bruce 
	
	
	
	
	discuss-bounces at lists.osgeo.org wrote on 24/02/2008 08:44:25 AM:
	
	> Bruce- 
	>   
	> It is not clear to me what sort of "study" you would need to 
	> convince you, as the ISO standard for encoding data into the 
	> JPEG-2000 file format is by construction mathematically and 
	> numerically lossless process.  (Indeed, "compression", i.e.
throwing
	> away bits so as to further reduce storage requirements, is
actually 
	> not defined within the scope of the standard.) 
	>   
	> -mpg 
	>   
	
	

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