pef vs dng

John Francis johnf at
Wed Oct 7 13:29:16 EDT 2009

On Wed, Oct 07, 2009 at 09:58:30AM -0600, William Robb wrote:
> So what you are saying is that Capture one is broken out of the box.

That might be putting it a bit strongly, but basically you're right.
Or, if not completely broken, at least more than a little crippled.
If you know how to extract information from a PEF, it's astonishingly
easy to get that same information out of a DNG (either one created
in-camera, or one produced by the Adobe DNG converter).  
Most RAW files are, like JPEGs, layered on a TIFF-EP file format.
Infrastructure that knows how to read TIFF-like files can extract
information from TIFFs, JPEGs, PEFs, NEFs, CRWs, and many others.
There is one stumbling block - the MakerNote offsets (which are
supposed to be relative to the start of the private data block)
are instead stored as absolute file positions in some RAW files.
Even that is covered by the DNG spec, though - there is a special
tag (MakerNote Safety) that can preserve the original file offset.

It took me only a short while to modify my PEF library to also
read DNGs - I doubt if it would be too dififcult for Capture One
to do the same.

Mind you, even a crippled version is better than some of the other
RAW converter products out there.  There is one (though just which
one I do not remember) that only offers DNG support for cameras
for which it has native RAW file support.  In other words it knows
enough about the DNG format to be able to track down and read the
camera-private data in the MakerNote tags, but nothing else.  At
least Capture One can read a DNG file from an unknown camera and
do something with the image data.

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