Archived posting to the Leica Users Group, 2010/04/30

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Subject: [Leica] LR question - Adobe or Camera standard profile
From: Frank.Dernie at btinternet.com (Frank Dernie)
Date: Fri, 30 Apr 2010 08:18:25 +0100
References: <!&!AAAAAAAAAAAYAAAAAAAAAGt4itF1rVtGmy0jR78k18rCgAAAEAAAAEcg3/IhaltHgS5aOA0ioHEBAAAAAA==@comcast.net> <4B6B47F3-1AAC-4B9F-BED3-E5191A5778B2@mac.com>

I may be wrong George, but I believe that JPG is a lossy compression, and 
that some, maybe quite a lot, of information is discarded from the raw data 
by the jpg process and is therefore not available again, it was not stored 
on the card, so expanding the jpg to any other format later can not recover 
it.
In fact, the advice not to work on and re-save as a jpg is the give away, if 
-nothing- was lost in the jpg process, this advice would be 
superfluous/wrong.
I always shoot raw, and only convert to jpg if needed.
I nowadays import my raw files into LR in native format, ie not converting 
to dng. This means the import is fast, and if there is any proprietary info 
stored in the makers raw format, such as distortion or chromatic 
corrections, which may not yet have a "place" in the current dng file 
format, it is not lost.
cheers,
Frank

On 30 Apr, 2010, at 00:01, George Lottermoser wrote:

> I agree that the jpg is what it is;
> but I believe
> when originally opened in photoshop
> (or other imaging software)
> it expands to reveal its maximum amount of information.
> To then save it as a tiff or psd or DMG
> does preserve whatever it did have to offer.
> 
> Working on a jpg and then saving as jpg
> will further throw away information.
> (or so I've been lead to believe).
> 
> So I do see some value, if choosing to shoot jpg,
> (which I don't)
> to then open the jpg and save as DMG
> for further nondestructive editing
> in LR or other software.
> 
> Regards,
> George Lottermoser
> george at imagist.com
> http://www.imagist.com
> http://www.imagist.com/blog
> http://www.linkedin.com/in/imagist
> 
> On Apr 29, 2010, at 5:49 PM, Oliver Bryk wrote:
> 
>> Vince,
>> there is really nothing of value that I can add to Frank's explanation. 
>> Your
>> in-camera JPG processor will have done whatever it was designed to do, and
>> AFAIK that is an irreversible process.
>> Oliver
>> 
>> 
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> 
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Replies: Reply from imagist3 at mac.com (George Lottermoser) ([Leica] LR question - Adobe or Camera standard profile)
In reply to: Message from oliverbryk at comcast.net (Oliver Bryk) ([Leica] LR question - Adobe or Camera standard profile)
Message from imagist3 at mac.com (George Lottermoser) ([Leica] LR question - Adobe or Camera standard profile)