Context: Ubuntu 20.04 and darktable 3.4.1 (configured with ‘scene-referred’ and ‘modern’)
I wanted to create the icc file for my sony a6600 following the article
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Hello @victor50, what is your question?
I saw your other thread as well. You can follow the instructions from here.
Bit of a caveat…this is a script that creates an icc from a mix of the jpg and the raw so it works like DT chart in a way except DT chart creates a style not an icc and this creates an icc file.
I know this is not what you are trying to do although it works nicely and I have modified it to work with a 24 patch card, however the instructions here for processing the raw should be sufficient for you to get a tiff to create your icc…Open your test shot select the history stack back at WB and compress …this will get rid of filmic and color calibration for this image. You can actually set it that way in preferences as well actually ie not to add anything to your image on opening … Now follow these instructions
Processing The RAW
Open the respective RAW in your favorite RAW processing
software, and disable all possible processing. Set linear
gamma (1.0) and set input and output profile to the same
profile, and rendering intent to absolute colorimetric if
possible, effectively creating a color management
pass-through. Then apply cropping, and lens distortion
correction if needed, be careful not to apply lens
vignetting correction. Then save to a 16-bit TIFF
(again without compression).
Particularly for Darktable, make sure camera white balance
is unchanged, disable basecurve, disable sharpen, set a
linear rec2020 for input and output color profile. Make
sure not to override the output color profile while
exporting.
Particularly for UFRaw, make sure camera white balance is
unchanged, restore details for negative EV: clip, clip
highlights for positive EV: digital linear, load Argyll’s
ClayRGB1998.icm both as camera and output profile, with
an absolute colorimetric rendering intent. Set output
bit depth to 16-bit. Set gamma 1,00 and linearity 0,000.
Also make sure Embed exif data in output is enabled.
Particularly for DCRaw, you can use the following command:
dcraw -v -w -M -H 0 -o 0 -6 -W -g 1 1 -f -m 1 -T …/_MG_1234.CR2
This should give you a tif that you can use with argyllcms…
The link I provided you in the other thread to Tomas Sobek’s website also has decent instructions…again just disable and ignore filmic and color calibration for now and set the parameters noted above to give you a linear unmodified TIff…it will be quite dark…
https://tomassobekphotography.co.nz/articles/create-camera-input-profile-with-ColorChecker-Passport.php
One other short cut. If you have access to Raw therapee it has a function to save a reference image that is linear and without any color management… THis takes care of all the configuring and you could use that as a source for your DT ICC.
Todd,
Thanks a lot for your exhauxtive explanation.
Could you please clarify what you mean with
"…for Darktable make sure camera white balance is unchanged
"
Or, in other words, should I disable ‘Scene-referred’ and ‘modern’ in DT processing preferences?
Ciao
Vittorio
My take would be yes…the scene referred or modern is an enhancement after std WB and input profile to bring the pipeline to D50. So it would be my assumption that you want your input profile with no impact. Basically the color calibration will respond to the corrections made by your new input profile if you use it later in time…Perhaps the in build colorchecker calibration will be an easier workflow as it builds yet again upon the input profile and the color calibration corrections to add tweaks to rgb channels to get an even better match but that will not be available unless you build DT or wait for the new release…Its also not hard to run your icc creation both with and without WB just to see how the results come out…I am no expert and perhaps someone who is need to write a little blur about the creation and integration of icc profiles into the new scene/modern workflows in DT