Archived posting to the Leica Users Group, 2013/05/08

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Subject: [Leica] Warning: Tech Stuff and Questions
From: douglas.sharp at gmx.de (Douglas Sharp)
Date: Wed, 08 May 2013 09:23:15 +0200
References: <E9886B64-65FB-4390-A1DB-5C1219D2C6A1@acm.org> <DF2FA96E-ABE9-4810-B66B-2B0631BA2742@gmail.com>

Hi Herbert,

I noticed the same with Canon DSLRs - the file size 
varies depending on the ISO value you use.

Cheers
Douglas




On 08.05.2013 04:50, Bob Adler wrote:
> Way beyond my pay grade!
>
> Sent from my iPad
>
> On May 7, 2013, at 4:46 PM, Herbert Kanner <kanner at acm.org> wrote:
>
>> Wanting an inexpensive camera for places/activities that could be risky 
>> for my M9, I jumped at the offer of a used Lumix DMC-LX5d on the LUG. 
>> After a dozen hours of learning how to cope quickly with the complex 
>> array of menus and doing some experemts with RAW, I come up with with 
>> some puzzlements for the techies among you,
>>
>> First, for comparison, here is how the M9 files are. Not using Leica's 
>> compression, the DNG files right out of the camera are exactly 36,4 MB. 
>> After going into Lightroom (LR4) the DMG files that LR stored from a set 
>> of twenty or thirty shots ranged in size from 19.2 to 22.2 MB. Clearly LR 
>> is doing some lossless compression--this started, I think, with LR3; LR2 
>> didn't do it. Interesting fact--note this later as you read--is that a 
>> Mac application called "Just Looking" will display images from RAW files 
>> and displays both the original and compressed versions equally.
>>
>> Next, here is the story on the Lumix RAW files. The files right out of 
>> the camera have ranged in size, again from a moderate set of shots, from 
>> 11.8 to 11.9 MB. That they are not identical in size is puzzling. Are 
>> they using some lossy compression from a sensor that puts out larger 
>> files? Also, I'd like to make a comment on the file size of RAW from this 
>> 10 megapixel camera. It would indicate that the data from each pixel is 
>> one byte. Well that is exactly the data size from an M9 if one uses 
>> Leica's lossy compression, which several LUGers have said is not visually 
>> detectable. I'm sort of ready to go along with this observation; human 
>> response to stimuli--all kinds--is logarithmic. That is each time you 
>> multiply the intensity of a stimulus by a constant factor, e.g., doubling 
>> it, the human thinks of that as uniform steps (think decibel!). So, the 
>> Leica 36MB minus whatever the EXIF data consumes is gross overkill!.
>>
>> Now a funny thing happens when LR turns those files into DNGs. The RAW 
>> files right out of the camera can be displayed by "Just Looking". But the 
>> DNG files produced from these by LR cannot. The files produced by LR are 
>> a bit more varied in size than the originals, ranging from 10.3 to 14.8 
>> MB.
>>
>> Can the techies among you shed any light?
>>
>> Herb
>>
>>
>>
>> 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
>
>




In reply to: Message from kanner at acm.org (Herbert Kanner) ([Leica] Warning: Tech Stuff and Questions)
Message from rgacpa at gmail.com (Bob Adler) ([Leica] Warning: Tech Stuff and Questions)