[argyllcms] Re: Calculate RAW importer profiles ?

  • From: Nikolay Pokhilchenko <nikolay_po@xxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Mon, 27 Jul 2015 11:34:57 +0300

Mon, 27 Jul2015, 9:41 +02:00 Adriaan van Os wrote:

My apologies if this has been discussed again. I searched for the word RAW in
the archives but got
quite a large number of hits.
Yes. I was discussed quite a lot. You may build abstract profile which links
together RAW output and JPEG output with some limits (gamut clipping problem
and may be something else).

A well known problem is that the output of RAW importers doesn't match the
gamut of the camera JPG
output. For example, when I import a Nikon .NEF with Nikon's proprietary
Caputure NX 2 software,
the produced TIFF matches the JPG exactly. When I import the same .NEF with
(say) the OS X built-in
CGImageSource RAW importer, the colors don't match. And I assume that
importers like dcraw and
ufraw have similar problems.
Why not to use proprietary software? Or, in contrast, your own profiles without 
any relation to proprietary SW?

Assigning different profiles to the TIFF imported RAW after import gives
different levels of
deviation from the camera JPG. Of course, the problem is that camera
manufacturers keep part of the
RAW image data format secret. And maybe, the RAW importers should do a better
job at color management.
May be. But better job requires more work of the professionals. Therefore this
is possible only in large manufacturer environment by employee professionals.

But many cameras do have an option to output both RAW and JPG. And the JPG
does reveal the secret
of how the imported RAW should look like (for a specific set of camera
settings). So, why not take
the JPG and the RAW imported TIFFs, compare them and calculate a "raw
importer" profile from both.
That profile, when assigned to the RAW imported TIFF would then represent the
best possible color
match with the JPG (for a specific set of camera settings).
If you carefully read the license agreements and the laws it may become clear
that discovering the secret is reverse engineering which may be not legal.

Would this be possible with argyll ? If so, it would offer users a quick way
to create a "raw
importer" profile from a (statistically relevant) set of RAW and JPG images.
Or at least it would
be better than the current (rather dissatisfactory) situation.
I can't imagine why the situation is dissatisfactory? By a cameras, use
proprietary software. If you need better results by another camera and another
software. There is nothing absolutely free in the world. You had to invest
either your money to by already made solution or spend your time to develop
your own (sensors, filters, cameras, software, profiles).
It's possible with ArgyllCMS. Not very straight by known way is to shoot the
target and to build both input profiles: RAW and JPEG. Then compute abstract
profile - the device link between these. Then apply the device link to RAW
image to obtain JPEG-like image.

Nikolay Pokhilchenko
Николай Похильченко

Other related posts: