negadoctor - custom working profile not selectable - frontier

[burakmartin]

Is there an existing issue for this?

• I checked and did not find my issue in the already reported ones

Describe the bug

Darktable docs for negadoctor mention this:

The working profile parameter in darktable’s input color profile module should be set to either linear Rec2020 RGB, or to an ICC profile representing the actual color space of your film emulsion. Some examples of such ICC profiles may be found in the following forum posts:

https://discuss.pixls.us/t/any-interest-in-a-film-negative-feature-in-rt/12569/177
https://discuss.pixls.us/t/input-color-profile-to-use-for-negatives/20271/13

Going to the second link, I've found an .icm profile for a frontier printer, Fuji_Frontier5-sRGB_CA-DPII_v3a.icm

The docs clearly state that these profiles can be set as a working profile, but this doesnt seem to work, I've downloaded the profile, put it in the /share/darktable/color/out folder (i also tried the /in folder) , but darktable does not let me pick them. Am I doing something wrong, or are the docs outdated?

Steps to reproduce

1. Go to https://discuss.pixls.us/t/input-color-profile-to-use-for-negatives/20271/13
2. Download the frontier icm profile (Fuji_Frontier5-sRGB_CA-DPII_v3a.icm)
3. Copy it into the /share/darktable/color/out folder
4. Restart darktable
5. Open darkroom tab
6. Select "input color profile" module and select a working profile
7. Notice that the frontier icm profile doesnt show up

Expected behavior

Darktable should let me select the frontier icm profile as a working profile in the input color profile module

Logfile | Screenshot | Screencast

No response

Commit

No response

Where did you obtain darktable from?

darktable.org / GitHub release

darktable version

5.4.0

What OS are you using?

Windows

What is the version of your OS?

Windows 11 Pro

Describe your system

No response

Are you using OpenCL GPU in darktable?

None

If yes, what is the GPU card and driver?

No response

Please provide additional context if applicable. You can attach files too, but might need to rename to .txt or .zip

No response

Hey Burak, hope you are well.

What's the full path for /share/darktable/color/in?

The docs say to put it in $DARKTABLE/share/darktable/color/in, where $DARKTABLE is your install location.

You can also hover over the dropdown and it might tell you where to place it:

The color/out, would be for the output color profile module:

ETA: Although, saying that, putting the profile in the color/in and color/out folders on my machine also doesn't put it in the working profile dropdown. It is available in input profile on the input color profile module and it is available in the export profile of the output color profile module.

[burakmartin]

I put it in both folders to be sure, /in and /out, for me they can be selected as export profiles, but the docs clearly state I should be able to set them as a working profile, which doesnt work. Howering the "working profile" also says I shoud put it into the /out folder

[wpferguson]

Put them in you darktable configuration directory, %LOCALAPPDATA\darktable\color\in (or out) and they should be picked up the next time you start darktable.

There is also a lua-script, contrib/color_profile_manager.lua, that gives you a GUI to manage your color profiles.

[burakmartin]

I already did that but they are not picked up as working profiles, no matter in which of these two folders (/in or /out) i put them, i restarted darktable multiple times, only shows up as a export profile or input profile, not in the working profile tab. Ill check the lua script once im home

[jenshannoschwalm]

The provided .icm doesn't work as a work profile as it does not provide a "matrix" which is required for a work profile. You can see the info in the log with -d dev btw. So not a bug for me. Not sure how that profile was generated ...

[burakmartin]

The provided .icm doesn't work as a work profile as it does not provide a "matrix" which is required for a work profile. You can see the info in the log with -d dev btw. So not a bug for me. Not sure how that profile was generated ...

Arent the docs misleading than? Im just wondering because the docs aswell as the person who provided the profile both mention that the ICM profile should be used as a working profile

[jenshannoschwalm]

For me such a profile doesn't make sense for work profile. Don't know who provided that file.

[Jiyone]

I think it's from a time where it was still possible to use such profile as working profile, which was wrong and been fixed afterwards.

[jenshannoschwalm]

Yes, that was like 3.8 or so.

[jenshannoschwalm]

BTW i have absolute no experience using that module ...

[Jiyone]

It is not related to negadoctor anyway, and better find a working profile that have a matrix. That's the only fix for this current issue.

[jenshannoschwalm]

It is not related to negadoctor anyway, and better find a working profile that have a matrix. That's the only fix for this current issue.

Fully agreed. There have been more issues like this with matrix-less .icc profiles. Yet - only for negadoctor we seem to suggest to use such as a working profile and i simply can't comment why that would be good at all.

[Jiyone]

It depends on how you digitize the film. But it is not necessary in most of cases, and keeping rec2020 is more than acceptable.
I digitize my color negative films using a custom narrow band RGB LED panel. With my Nikon Z6 and my film is between my camera and the light, it produces a "technical only" image that has no real meaning by its substance, only that each CMY layer's transmittance is mapped to the corresponding raw RGB channel. Negadoctor is a kind of converter from the digital transmitance data to film density data. So there is no use of a specific working profile because, at the step of the Input profile module, it's the data of the digital camera (or the scanner) that is involved.

[burakmartin]

It depends on how you digitize the film. But it is not necessary in most of cases, and keeping rec2020 is more than acceptable. I digitize my color negative films using a custom narrow band RGB LED panel. With my Nikon Z6 and my film is between my camera and the light, it produces a "technical only" image that has no real meaning by its substance, only that each CMY layer's transmittance is mapped to the corresponding raw RGB channel. Negadoctor is a kind of converter from the digital transmitance data to film density data. So there is no use of a specific working channel because, at the step of the Input profile module, it's the data of the digital camera (or the scanner) that is involved.

Interesting! I just started scanning with a narrow band rgb light, I created a custom color profile for my camera for that specific rgb light and set it as a my input profile, for working profile I use linear rec 2020 (I've tried the FilmNegRGB_650_550_460-elle-V4-g10.icc profile which sometimes gives me more vivid colors after inversion), I dont fully understand the working profile, but I'm basically chasing the frontier scanner look. I guess that's pretty difficult to achieve, and I was hoping to get closer to it by setting the frontier profile as the working profile. What would make sense though is setting my export profile to the one of a frontier printer, which is not the scanner, but whatever it has frontier in its name
Is your workflow similar?

[Jiyone]

I don't use an other input profile than the standard matrix.
I may be wrong, but by experience I believe that using an input profile based on the panel's LED is not necessary at all for negative film since it have no meaning. It is not like a photography depicting something. You don't want the color of the dye against the LEDs, only the dye transmittance.