Archived posting to the Leica Users Group, 2006/02/25

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Subject: [Leica] Daily Dose of Spring XI
From: ericm at pobox.com (Eric)
Date: Sat Feb 25 04:25:35 2006
References: <9b678e0602221659y6619bb2fp9176ecef4b4598ba@mail.gmail.com> <43FD1511.1060904@adrenaline.com> <9b678e0602221852u567a926x9a66976d75ee468e@mail.gmail.com> <43FD2791.9040206@adrenaline.com> <9b678e0602221916j5df65dd9t2b2a286b9f194341@mail.gmail.com> <066141F2-F013-464B-934F-FA3F493B5DA9@ralgo.nl> <6.2.3.4.2.20060223133203.02a83060@mail.rhtc.net> <EEE0C0BF-5895-4C66-94F6-30C1260279BE@ralgo.nl> <1140769617.43fec351bcddc@www.uusikaupunki.fi>

Raimo:

>If you select to save JPGs using original quality it will not be
>compressed again - at least the programs I use do it this way.

I would be careful.  All JPG compression is lossy.  That is, when you save
the jpeg file, it throws away some information.  So the next time when you
open the file, it doesn't have 100%.  Which is fine for saving once and
viewing.  But if you save again, then you're tossing out more information.
Viewing jpegs is fine.  And there are some programs that can rotate jpegs
without losing information.  But if you save again, you will lose
information.  If you save using the original quality, I'm guessing that
means use the same level of compression that was first used.  If you change
an image and then save the jpeg again, it *will* be compressed again.
That's the way jpeg works.



--
Eric
http://canid.com/

Replies: Reply from raimo.m.korhonen at uusikaupunki.fi (Raimo K) ([Leica] Daily Dose of Spring XI)
In reply to: Message from don.dory at gmail.com (Don Dory) ([Leica] Daily Dose of Spring XI)
Message from scott at adrenaline.com (Scott McLoughlin) ([Leica] Daily Dose of Spring XI)
Message from don.dory at gmail.com (Don Dory) ([Leica] Daily Dose of Spring XI)
Message from scott at adrenaline.com (Scott McLoughlin) ([Leica] Daily Dose of Spring XI)
Message from don.dory at gmail.com (Don Dory) ([Leica] Daily Dose of Spring XI)
Message from bruce at ralgo.nl (bruce) ([Leica] Daily Dose of Spring XI)
Message from images at InfoAve.Net (Tina Manley) ([Leica] Daily Dose of Spring XI)
Message from bruce at ralgo.nl (bruce) ([Leica] Daily Dose of Spring XI)
Message from raimo.m.korhonen at uusikaupunki.fi (Raimo K) ([Leica] Daily Dose of Spring XI)