Anyone Archive Their RAW Images as DNG's

Archived from groups: rec.photo.digital (More info?)

Russell wrote:
> Anyone archive their RAW images as DNG's?
>
> If so, have you noticed that the DNG file sizes are approx. 1-2MB smaller?
> Why is this, are they compressed slightly during the conversion?
>
>
Depends entirely on what the camera raw file was. A DNG will
be larger than the Foveon X3F file it was converted from,
whereas if you start with a Pentax PEF file the DNG will be
much less than the original. The data in a DNG is compressed
using lossless JPEG compression.

--
Regards

John Bean

Archived from groups: rec.photo.digital (More info?)

Russell wrote:

> Anyone archive their RAW images as DNG's?

I just began exerimenting.

>
> If so, have you noticed that the DNG file sizes are approx. 1-2MB smaller?
> Why is this, are they compressed slightly during the conversion?


That seems a good reason to go through the conversion. There is an
involved discussion in rec.photo.digital.slr-systems under the title
something like "ACR DNG 3.x available for download".

--
Paul Furman
http://www.edgehill.net/1
san francisco native plants

Archived from groups: rec.photo.digital (More info?)

Russell wrote:
> Anyone archive their RAW images as DNG's?

I only archive the DNGs. Once I have DNGs in 2 places, I delete the
original Raw. This is NOT recommended practice, and contradicts Adobe's
advice.

> If so, have you noticed that the DNG file sizes are approx. 1-2MB
smaller?
> Why is this, are they compressed slightly during the conversion?

Yes, there is optional compression. Compression is lossless. It can be
reversed simply by re-converting with the option switched off. (DNG is
one of the Raw formats that the DNG Converter accepts as input).

There is also an option to embed the original Raw file inside the DNG.
Some people use that for archive purposes, because, while it has the
convenience of being one file, it offers the ability of regaining the
original Raw file as a separate file. Obviously, the result is larger,
but for the Pentax it is not as large as the sum of the 2 separate
files. I guess that is because the converter compresses the embedded
original file. (I don't use this option - I just tested it).

Another potentially useful feature is that, if you use xmp sidecar
files, the DNG Converter will embed the contents of the sidecars into
the resultant DNG, so you can archive the ACR settings as well in just
the one DNG file. (ACR 3.1 also offers this as an option).

It is absolutely clear that Adobe see DNG, not just as a common Raw
format, but also as a strategic storage (and presumably transmission)
format for future Raw workflows. It is becoming as comprehensive at the
Raw-processing stage as PSD is at the photo-editing stage.

--
Barry Pearson
http://www.barry.pearson.name/photography/
http://www.birdsandanimals.info/

Archived from groups: rec.photo.digital (More info?)

In message <3e7k40F1jp2oU1@individual.net>,
John Bean <waterfoot@gmail.com> wrote:

>Depends entirely on what the camera raw file was. A DNG will
>be larger than the Foveon X3F file it was converted from,

Speaking of xf3 files, I must say that after looking at the RAW data in
some of them very closely, it seems that as three separate greyscale
channels, or one (combined), noise is extremely low, and readout
artifacts are almost non-existent. It's just a shame that the data is
very hard to get accurate hue info from. I'm sure that the SD10 makes
an excellent camera to make 3.4MP greyscale images from, albeit with a
little aliasing.
--

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John P Sheehy <JPS@no.komm>
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