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: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] 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 [EMAIL PROTECTED] 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 > Notice: This email and any attachments may contain information that is personal, confidential, legally privileged and/or copyright. No part of it should be reproduced, adapted or communicated without the prior written consent of the copyright owner. It is the responsibility of the recipient to check for and remove viruses. If you have received this email in error, please notify the sender by return email, delete it from your system and destroy any copies. You are not authorised to use, communicate or rely on the information contained in this email. Please consider the environment before printing this email.
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