Pascal de Bruijn wrote:
On Mon, Jul 27, 2015 at 9:41 AM, Adriaan van Os <gpc@xxxxxxxxxxxx <mailto:gpc@xxxxxxxxxxxx>> 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.
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
"Problems" yes... except that it's a problem intentionally created by the camera vendor, by keeping their color handling secret.
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.
This problem is entirely a vendor problem. Most RAW converters color management is just fine. They just can't know the magic parameters (LUT?) the vendors use. And even if they did, they might not be able to legally use them. So you end up in a situation where isn't a single reason why it's reasonable to expect the same output from a third party RAW converter to be the same as the camera JPG.
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).
I've cobbled this up, with some help from others on this list, in the past.
It's very experimental, so it may or may not work well for you. Please do read the included README thoroughly before trying.