[Leica] M9 DNG compression

[john at chiaroscuro.co.nz (John McMaster)]

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
> >