[Leica] M9 DNG compression

[kanner at acm.org (Herbert Kanner)]

See the link in John McMaster's post. It's clear that Leica's 
compression requires trivial processing. Lossless LZW or whatever 
would take much too much processing.

Herb


>Not sure if it is a processing limitation or if a firmware update can make
>it lossless like the S2....
>
>john
>
>-----Original Message-----
>
>
>I also shoot compressed because of the write speed. I use 16 GB cards so
>storage is hardly ever an issue.
>
>Here's a thread on the actual algorithm used, which I found somewhat
>surprising.
>http://www.l-camera-forum.com/leica-forum/leica-m9-forum/206098-dng-compress
>ion-any-difference-quality-2.html
>
>  I guess normal LZW / zip type of compression takes too much processing
>time. Come to think of it, I'm surprised that no one in the camera industry
>has designed a "compression" FPGA chip....
>
>On Thu, Dec 29, 2011 at 1:53 PM, Henning Wulff
><henningw at archiphoto.com>wrote:
>
>  > I too have never seen a difference to date. Early on I shot a number
>  > of comparisons to make sure I wasn't doing something stoopid, but as a
>  > result of those tests and information from Leica I now shoot
>  > compressed. It's not a matter of disk space or card space, but of
>  > speed. The buffer in the M9 is small enough, and clears slowly enough
>  > that any speed enhancement is noticeable, and there is a BIG
>  > difference in the speed. Try shooting a buffer full of compressed vs.
>  > non-compressed images and see how long it takes for the buffer to clear
>(write light to stop blinking).
>  >
>  > I don't shoot in continuous mode, but I do expect the camera to be
>  > ready when the shot arrives in the viewfinder. When the buffer is
>  > full, the shot is often gone by the time the camera is ready again.
>  >
>  > Henning
>  >
>  >
>  > On 2011-12-29, at 12:41 PM, John McMaster wrote:
>  >
>  > > I don't think any real difference has been seen at this stage. The
>  > > main thing is whether future software can bring more information out
>  > > of a DNG file which may be lost if compressed. I shoot uncompressed
>  > > and deal with
>  > the
>  > > data ;-)
>  > >
>  > > john
>  > >
>  > > -----Original Message-----
>  > >
>  > >
>  > > Has anyone ever done a comparison of the 34.6 Mb Leica DNGs to the
>  > > compressed versions which are 18 Mb more or less depending on the
>  > > degree
>  > of
>  > > detail in the image? While it is not an issue for me, with a mere
>  > > 1000 to
>  > > 2000 images per year, terabyte drives being so cheap, It probably is
>  > > an issue to the much more prolific professional photographers.
>  > >
>  > > The question is: has anyone ever found an image where this degree of
>  > > compression has been seen to matter?
>  > >
>  > > Herb
>  > >
>
>
>
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-- 
Herbert Kanner
kanner at acm.org
650-326-8204

Question authority and the authorities will question you.