how to colour profile

Software RawTherapee
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hi, I am stuck and not technical…i got as far as importing the DCP profile photo of the Colour Checker onto Raw Therapee (editor- colour management - folder - clicking on DCP colour profile file) but i don’t know how to then change the colours in the photos of my paintings using that colour profile…
can anyone help please…

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Hello @jsmith, welcome to the forum and for reaching out!

I am taking a guess here that “the DCP profile photo” simply means a photo you took of a color chart, correct? You then want to use that calibration and apply it to other photos?
There is no copy-and-paste way to do that in RawTherapee I am afraid. It will require the use of (rather finnicky) tools outside of RawTherapee, called DCamProf and Argyll, or commercial software.
There is a description here if you want to try it out yourself: How to create DCP color profiles - RawPedia

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yes.

i take it there are free software outside of raw therapee to do the dcp photo -

yes but what i mean once i export it to raw therapee - i need to go to these places -

a few things i cannot see on Raw Therapee =
‘Develop Module’
‘Camera Calibration’
‘Imitation Shot’

do you know where these things are please?

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Could you tell me where you have read these terms? They do not sound like typical descriptions for what is available inside RawTherapee, and I do not want to give you bad advice on what to do based on guesswork.

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Sounds more like darktable?

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Hi!

  • There is no specific Develop Module, RawTherapee always shows the result of the development according to your settings (sometimes only at 100% zoom)
  • Camera Calibration is done by the camera profiles that come with RawTherapee, except you are using some rare and exotic camera
  • I guess you mean the software should find the same settings as used in the OOC jpeg? A first approach would be using the auto-matched tone curve.
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If what you’re asking is, how to change colors in a photograph using DCP profiles, you’ll find plenty of good information about that in the dcamprof documentation:

https://rawtherapee.com/mirror/dcamprof/dcamprof.html
http://rawtherapee.com/mirror/dcamprof/camera-profiling.html

Be advised, it’s not that un-technical, you’ll have to learn a bit about how digital color is done.

The same developer used the code from dcamprof to make a commercial tool, Lumariver. If you’re looking to do reproduction work, it’s worth consideration. I generally don’t care much for paid software, but this is one glaring exception.

http://www.lumariver.com/

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This* is provided by a proprietary plugin (?) that can be added to Lightroom, to interface with color checker photos, based on what I’ve seen. It appears to be superficially similar to the color checker interface in darktable’s color calibration module. I’m familiar with neither, though.

*‘Develop Module’
*‘Camera Calibration’
*‘Imitation Shot’

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thanks i cannot afford any paid software, someone recommended darktable to me…

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dcamprof is the open-source command-line core of Lumariver. I use it all the time to make ICC camera profiles, and it also makes DCP profiles.

The dcamprof documentation is worth spending time with by itself; Anders does a good job of explaining things relevant to profile making. dcamprof will also do “look” manipulations, which might be for what you’re looking…

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thanks, i take it it is free?

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Indeed, free.

https://github.com/Beep6581/dcamprof

Now, there’s no release at this page, just the source code. It’s not hard to compile, but if that’s daunting I made a windows build of it which you can download here:

https://glenn.pulpitrock.net/dcamprof-1.0.6.zip

It’s a command-line program, a bit daunting to use, but Anders’ documentation has everything from recipes to theory. Also, if you have questions, there are a few of us here that probably know the answers…

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great thanks very much! So i gather you’ve used a colour checker/ imported it into this site yourself then?

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Yes. I own a ColorChecker Passport. I’ve tried a few others, but they all produced more glare than the Passport.

Now, I don’t use RawTherapee, so I’m not familiar with procedure you’ve been reading, but the key is to process the raw image of the ColorChecker with only black subtract (you shouldn’t have to worry that one in RT, it’ll do it for you), demosaic, and white balance. No tone curve or any other processing. Oh, it does help Argyll scanin if you crop the image to just outside of the patches, saving the registration marks.

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Thanks Glenn, i will try dcamproff you’ve recommend for this job…

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darktable is free. But please do not expect a free clone of Lightroom: darktable is about control, not dragging 3 sliders.

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For darktable and the color checker, start here:

https://docs.darktable.org/usermanual/4.0/en/module-reference/processing-modules/color-calibration/

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Adobe has a DNG profile editor that you can use with a color checker or you can select multiple colors and alter them. It’s free if you run Windows… Is that perhaps what you saw??

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hi Glenn,

when you take the initial photo of the color checker, i will be doing it outside, i take it you just shoot in the right light - not glaring, not too dark, do i need to shoot with the white balance changed?

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I try to shoot my daylight target shots mid-day, so I can call the color temperature 5500K. No clouds in the vicinity of the sun, just direct light. I control the glare with the angle of illumination on the target, and the ColorChecker Passport makes it easy to get an angle bereft of glare.

You don’t need to mess with white balance at the time you take the shot, unless you want a good “as-shot” number in the image metadata. You should be able to get a good white balance in post with a patch from any of the lighter neutral patches.

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