Archived posting to the Leica Users Group, 2012/12/10

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Subject: [Leica] DNG compression???
From: kanner at acm.org (Herbert Kanner)
Date: Mon, 10 Dec 2012 00:06:13 -0800
References: <540D27C0-778A-4F70-BAD7-C8A0EB0F9F5A@acm.org> <CAE3QcF6OzuDrm6JRNHz62j7a6_Rw9W5667s2y9P+A4=JKVcHhQ@mail.gmail.com>

Thanks Geoff. I take it then that it's the RAW processor in Lightroom and 
not a camera firmware update that introduced the lossless compression. I 
think that change was between LR2 and LR3.

Re the compression from 16 (actually only fourteen bits of data in a 16 bit 
container) to 8 bits being undetectable, I believe it, but I have plenty of 
disk space; at the rate I'm shooting, disk space will outlive me. However, I 
tried compressing in the camera in the hope that I would see a speed-up, 
i.e. an increase in the number of continuous exposures that could be made 
before the camera stopped dead because of a full buffer. I could not see a 
noticeable change in this number between compressed and uncompressed, so I 
just reverted to uncompressed for no particularly valid reason.
Herbert Kanner
kanner at acm.org
650-326-8204

Question authority and the authorities will question you.




On Dec 9, 2012, at 1:23 PM, Geoff Hopkinson wrote:

> Herbert you have several items in there.
> Firstly if you use compressed DNG set in camera you give up almost nothing
> to gain the savings in file sizes. Some argue that you cannot see any
> difference at all. While it is technically lossy, this does not mean the
> change is significant and there is no futher loss on resaving, unlike where
> you save new versionsa as new JPGs..
> Secondly on import in an Adobe raw processor (ACR or LR) truly LOSSLESS
> compression is applied. In recent program versions that is the default (and
> now only) process because there is no downside at all.
> If you open previously uncompressed on import DNGs and do some editing, for
> example a WB change that LOSSLESS compression is applied.
> Thirdly , whether you originally shot with your camera set for compressed
> or uncompressed DNGs, those files are further losslessly compressed by the
> Adobe program on import (or first editing and saving for earlier program
> versions).
> 
> Cheers,
> Geoff
> http://www.pbase.com/hoppyman
> 
> 
> 
> On 10 December 2012 06:39, Herbert Kanner <kanner at acm.org> wrote:
> 
>> Hi LUGers,
>> 
>> I'm looking for some enlightenment from anyone who knows. The question has
>> to do with the size of Leica DNG files. Back in August, 2010, I had a set
>> of DNGs all but one of which were 36.4 MB in size.  All of those taken the
>> same afternoon at the same general location. Similarly, using Leica's
>> compression, in December, 2011, I found a set of DNGs taken the same day,
>> at 18.3 MB.
>> 
>> Then, in November, 2011, there was a set taken the same day, where the
>> file sizes varied from 19.6 to 23.1 MB. Was this a result of a firmware
>> update in which Leica probably introduced LOSSLESS compression? To round 
>> up
>> the picture, I found a set in August, 2012, where the size range was 8.5 
>> to
>> 10.3 MB, undoubtedly where I set "compressed DNG" on the camera.
>> 
>> 
>> 
>> Herbert Kanner
>> kanner at acm.org
>> 650-326-8204
>> 
>> Question authority and the authorities will question you.
>> 
>> 
>> 
>> 
>> 
>> _______________________________________________
>> Leica Users Group.
>> See http://leica-users.org/mailman/listinfo/lug for more information
>> 
> 
> _______________________________________________
> Leica Users Group.
> See http://leica-users.org/mailman/listinfo/lug for more information



Replies: Reply from hopsternew at gmail.com (Geoff Hopkinson) ([Leica] DNG compression???)
In reply to: Message from kanner at acm.org (Herbert Kanner) ([Leica] DNG compression???)
Message from hopsternew at gmail.com (Geoff Hopkinson) ([Leica] DNG compression???)