[Leica] Very very odd behavior of M8 and Adobe Lightroom with DNG and TIF files

[lug at steveunsworth.co.uk (Steve Unsworth)]

All perfectly normal :-)

I'm guessing you use an XP machine. The DNGs becoming Tiffs appears to be an
OS issue - the OS sees the DNGs as Tiffs and therefore renames them - thank
you very much! This doesn't happen with a card reader.

When you're running the DNG through the Adobe converter you're selecting the
lossless compression option. This is typical of the compression achieved -
the original M8 files are uncompressed.

The reason the Leica, and hence the converted, DNG, files are so small is
that Leica uses a non-linear processing algorithm to convert the data from
the sensor to 8 bits. This is then expanded back to 16 bits when the file is
opened - it's a bit like dbX recordings from the late 70s/early 80s if you
remember those that extended an LPs dynamic range by compressing the
recording before pressing and then expanding it again on playback.

Steve


On 3/4/07 21:13, "Clive Moss" <clive.moss@gmail.com> wrote:

> While packing to go away, I broke my usual procedure and connected the
> M8 directly into the USB port rather than taking the card out and using
> card reader as I usually do. I thought it would save me a little time.
> 
> Odd behavior #1: I was shooting DNG - the images arrived in Lightroom as
> TIF files, apparently good in all other respects.
> 
> Odd behavior #2: On a whim I did the Lightroom "Convert to DNG" thing.
> With my Nikon files doing this usually resulted in a large increase in
> the file size. With the M8 originated tif, the file sizes halved, from a
> constant 10,335 KB to a variable 5,800 to 6,000 KB. Looks like the tif
> is compressed, whereas the dng is uncompressed.
> 
> Odd behavior #3: I opened the DNG in Photoshop CS3 to see if it was a
> good file - it was. saved is a a 16 bit tif with zip compression. 58,217
> KB. Saved as 16 bit tif with LZW compression - 76,840 KB.
> 
> Not so odd behavior: For my last trick, I renamed a regular dng file as
> TIF and opened it in CS3. Worked perfectly. Not surprising - dng is just
> a special tif.
> 
> I will not be able to work on this (or take it to the Adobe forum where
> it belongs) while I am away - but I find it very interesting. May be
> able to halve my disk usage with DNG?
> 
> Bye for three weeks. I leave tomorrow.