Color management sanity check

[boredphoto (Fabio)]

Hi, I need to understand if I’m doing color management right. These are my notes. Sorry for the wall of text, but I want to share all the information I know. My doubts and questions in the late section.

Devices

I’m using an old Eizo CG247 that has an built-In selfcalibration sensor.
I calibrated it on Windows with the Eizo ColorNavigation software and moved the profile on Linux:

Operating System: Kubuntu 22.04
KDE Plasma Version: 5.27.9
KDE Frameworks Version: 5.104.0
Qt Version: 5.15.3
Kernel Version: 6.2.0-37-generic (64-bit)
Graphics Platform: X11

Installed on KDE:

Monitor setup

Following settings are suggested by the print shop (details in next section):

Brightness: 100cd/mq
Temperature: 5800K
Gamma: 2.2
Color Gamut: Adobe RGB.

Printing

I’m working on a photo book and the print shop is telling me:

RGB images (with Adobe RGB 98 as color space). We separate the images using the FOGRA 51 standard on our Ricoh C7100X press. If you want to simulate color shifts in Photoshop, you’ll need to use the CMYK profile of the FOGRA 51 in relative colorimetric mode.

So after looking for more information, I downloaded the PSO Coated v3 ICC profile that I want to use to simulate the printer in the darktable preview. Just to be sure print will be ok.

Darktable setup

Following the documentation I’m checking darktable configuration.

➜  ~ darktable-cmstest 
darktable-cmstest version 4.5.0~git1394.269e5743-1+11010.1
this executable was built with colord support enabled
darktable itself was built with colord support enabled

primary CRTC is at CRTC 0
CRTC for screen 0 CRTC 1 has no mode or no output, skipping
CRTC for screen 0 CRTC 2 has no mode or no output, skipping
CRTC for screen 0 CRTC 3 has no mode or no output, skipping
CRTC for screen 0 CRTC 4 has no mode or no output, skipping
CRTC for screen 0 CRTC 5 has no mode or no output, skipping

DisplayPort-2   the X atom and colord returned the same profile
        X atom: _ICC_PROFILE (1236 bytes)
                description: CG247
        colord: "/home/fabio/.local/share/icc/edid-992a0aac92952e214927cff0dfba7ab4.icc"
                description: CG247

Your system seems to be correctly configured

I’ve added the PSO Coated v3 profile here:

➜  ~ ll .config/darktable/color/out 
total 2.1M
-rwxr-xr-x 1 fabio fabio 2.1M Sep  4  2015 PSOcoated_v3.icc

Darktable warning and doubts

In this screenshot, I’m trying to summarize the setup and the darktable’s warning (details after the screenshot):

Display profile: Adobe RBG (Compatible)

Question 1: do I have to use ‘system display profile’ ? My gut answer is yes.

Preview display profile: PSO Coated.

This is the printer profile. And if everything is setup correctly, on the left window I have a preview of how the image will appear on paper.

Question 3: If you look carefully on the right side there is a warning:

unsopported output profile has been replaced by sRGB

This warning makes me think that the printer profile is not applied, but I have no idea how to solve it. What can I do to be sure that I’m previewing the images with the right profile?

Question 4: instead of using the preview on a separated window, I’d like to use Ctrl+s to toggle the softproof on/off. So I set it up like this:

As you can see I get another error, this time related to the vectorscope profile (but there are no vectoscope profiles in the dropdown). What am I doing wrong?

Last but not least, the PSO Coated v3 profile I downloaded from the ECI website looks ok and not corrupted:

Thanks for any suggestion and help!

[KarlMagnusLarsson (Magnus Larsson)]

I have an EIZO CG279X and calibrate using Windows ColorNavigator7 app and transfer icc profile to Linux.

@boredphoto

Display profile: Adobe RBG (Compatible)

Question 1: do I have to use ‘system display profile’ ? My gut answer is yes.

Yes, set it to system display profile

@boredphoto

Preview display profile: PSO Coated.

This is the printer profile. And if everything is setup correctly, on the left window I have a preview of how the image will appear on paper.

Do not use a printer soft prof profile for this. I use ‘system display profile’.

@boredphoto

Question 3: If you look carefully on the right side there is a warning:

unsopported output profile has been replaced by sRGB

This warning makes me think that the printer profile is not applied, but I have no idea how to solve it. What can I do to be sure that I’m previewing the images with the right profile?

I have a hard time to understand what is going on here. Are you displaying a jpg file? What is the color profile of the jpg file? For instance exiftool -icc_profile:* photo.jpg. I have not seen this error before.

@boredphoto

Question 4: instead of using the preview on a separated window, I’d like to use Ctrl+s to toggle the softproof on/off. So I set it up like this:

As you can see I get another error, this time related to the vectorscope profile (but there are no vectoscope profiles in the dropdown). What am I doing wrong?

Same here. I can not help. I have not seen this error before. Softproof works fine for me with various soft proof printer profiles I get from the printing company I use.

EDIT:

@boredphoto

ast but not least, the PSO Coated v3 profile I downloaded from the ECI website looks ok and not corrupted:

Is this profile intended to be used for Soft Proof? I do not know, but it is stated Output device. EDIT2: I do not have full insight into which profiles I can use for soft proof. I asked the printing company and they pointed to their web page with profiles for soft proof.

[priort (Todd Prior)]

CMKY… will that work??

[sugarbravo (Šarūnas Burdulis)]

I would suspect that “Default: CG247” is not the profile you created and moved to Linux.

The one you created is either the unchecked one or still needs to be added by locating its .icc.

[KarlMagnusLarsson (Magnus Larsson)]

For me, after getting the monitor icc profile from calibrating using Windows ColorNavigator7 from EIZO and transfering icc-profile to linux:

./darktable-cmstest
darktable-cmstest version 4.5.0+1401~gc2455d4619
this executable was built with colord support enabled
darktable itself was built with colord support enabled

primary CRTC is at CRTC 0
CRTC for screen 0 CRTC 1 has no mode or no output, skipping
CRTC for screen 0 CRTC 2 has no mode or no output, skipping
CRTC for screen 0 CRTC 3 has no mode or no output, skipping

DP-2	the X atom and colord returned the same profile
	X atom:	_ICC_PROFILE (8416 bytes)
		description: CG279X(35945120)10Display-100-D65
	colord:	"/home/magnus/.local/share/icc/CG279X(35945120)10Display-100-D65.icc"
		description: CG279X(35945120)10Display-100-D65

Your system seems to be correctly configured

The default profile name from EIZO app ColorNavigator application becomes: CG279X(35945120)10Display-100-D65: MonitorType-Serial-Candelam2-colortemp.

[boredphoto (Fabio)]

I recalibrated the monitor and I see the profile. I think the issue is on PSO Coated profile. Even on other software doesn’t work. Maybe is not intended for what I want to do. In any case, I asked the print shop to share their profile. I’ll update the post if I get a hit.

➜  ~ darktable-cmstest 
darktable-cmstest version 4.5.0~git1402.9f0088ce-1+11013.1
this executable was built with colord support enabled
darktable itself was built with colord support enabled

primary CRTC is at CRTC 0
CRTC for screen 0 CRTC 1 has no mode or no output, skipping
CRTC for screen 0 CRTC 2 has no mode or no output, skipping
CRTC for screen 0 CRTC 3 has no mode or no output, skipping
CRTC for screen 0 CRTC 4 has no mode or no output, skipping
CRTC for screen 0 CRTC 5 has no mode or no output, skipping

DisplayPort-2   the X atom and colord returned the same profile
        X atom: _ICC_PROFILE (8388 bytes)
                description: CG247(22339064)02Adobe RGB
        colord: "/var/lib/colord/icc/CG247(22339064)02Adobe RGB.icc"
                description: CG247(22339064)02Adobe RGB

Your system seems to be correctly configured

[KarlMagnusLarsson (Magnus Larsson)]

You are running Adobe profile. You could consider selecting ‘native’ in case monitor can do a bit better than Adobe RGB in some color corners of color space.

[Leniwiec (Michał)]

PSO Coated is a CMYK profile I use at work to convert RGB images to commercial CMYK offset press printed on a coated paper stock (I work at a print shop).

From time to time I did use Darktable’s softproof function with both PSO Coated and ISO Coated v2 ECI and didn’t have any issues.

[boredphoto (Fabio)]

hey @KarlMagnusLarsson thanks for the suggestion. How can I use the native option? I understand the logic, but not sure the right step to follow for the setup.

[priort (Todd Prior)]

Ya NP… I was going from memory and had seen this in the past and also thought that DT would have no idea what to do with CMYK on any level…

Soft proofing with darktable

I know this topic is a little bit stale by now, Bit in the meantime I have discovered what issues the original poster might have had. So I just writhe my thoughts here for reference: Some print shops offer their soft proofing ICC profiles only as CMYK profiles and then the darktable has an issue with displaying the soft proof (I stumbled upon this issue recently). As a quick workaround it helps to use gimp for soft proofing in this case. e.g. the ICC profiles here: cyberlab.at | Das Hi-Tech Fo…

[KarlMagnusLarsson (Magnus Larsson)]

Hello @boredphoto,

@boredphoto

How can I use the native option?

When I start ColorNavigator7 on Windows the main window states a target for the selected profile: Brightness, Black level, contrast, White-point Gamma, Priority, and Gamut.

EDIT: You might have to define your own new target, which you can edit, when it comes to the different settings.

For Gamut I can select: BT2020,BT709,DCI,sRGB, AdobeRGB, or native as a target.

My CG279X EIZO monitor is 99% of AdobeRGB, but that is just because the native gamut does not cover 1% of AdobeRGB in one corner. In all other places the monitor can do better than AdobeRGB

If I select Adobe RGB as gamut target, then I miss some color gamut in blue and red areas.

The ColorNavigator manual is here: https://www.eizo.com/prodeizo/media/contentassets/2020/07/22/UM-03V27604K1-EN.pdf.

EIZO makes many different monitor models and I suppose it varies what you can do and what native means.

On Linux side I transfer icc profile from windows and make sure the monitor operates in the calibrated state, selecting that target.

[LaurenceLumi]

Coupling quick points.

If your using colornavigator to create the profile it will be for one of the CAL presets not the AdobeRGB or any of the other one in list in your screenshots. That your first mistae. On my CG243W connected to the display port. The preset is CAL3. At least that how it wors if you want to use the built in LUT in the monitor.

I found that gnome color manager didn’t wor properly for me under Ubuntu 22.04. I use argylCMS it sets the xatom property, so that CMM apps can see your profile.

When the print shop said use AdobeRGB, what they meant was send them a file, where they data contained in represents data for the AdobeRGB colorspace, ideally with a AdobeRGB colorspace tag in the file.

You want your monitor to display the widest gammut possible, as you want to do softproofing, because you ideally want to simulate the your printer, not AdobeRGB

Hope that helps rather confuses.

[boredphoto (Fabio)]

Hey @LaurenceLumi thanks for your reply.
In ColorNavigator I can calibrate the monitor at any profile.

So far example:

AdobeRGB

I click on calibrate, ed after the calibration i got the ICC profile in

“C:\Windows\System32\spool\drivers\color\CG247(22339064)02Adobe RGB.icc”

CAL3

I did the same on CAL3. The difference is that I can fine tune the target as @KarlMagnusLarsson suggested above.

After the calibration I get this profile.

“C:\Windows\System32\spool\drivers\color\CG247(22339064)10100cd_Minimum_5800 K_2.20_Native.icc”

I switch the 2 mode from ColorNavigator OR clicking the Mode button on the monitor, they are very very similar (nothing change to my eyes) because they are calibrated at 5800Km 100cd/mq and gamma 2.2.

In my original post I was using the AdobeRGB profile above.

My monitor had 3 CAL mode, and there is no mention about the relation between the Display Port and the CAL3 profile.

Maybe is my gut feeling but in Linux (as well Windows) if I force the Mode AdobeRGB from the physical button on the screen I think it is using the embedded profile from my monitor.
And still in Linux as I do not have color navigator running probably is better to use the standard mode AdobeRGB instead of CALx (unless the software on Linux can share the current ICC profile to the monitor and viceversa). If I got it well ArgyllCMS is solving this problem. Am I understood this correctly?

[boredphoto (Fabio)]

Thanks @KarlMagnusLarsson I recalibrated using your suggestion. As I wrote below in another answer the difference are invisible to my eyes but I understand why this is better.

There is another doubt I have.

By default darktable is using the following export profile:

When I export the images I use the default image settings in the Export module:

I’m using the default because I’ve been reading that is better to use them unless you know what are you doing.

The print I got from the service are very close to my editing so at least with my previous setup I did it right.

I’m wondering if there will be any benefit exporting the pictures using a different profile.

[LaurenceLumi]

I dont use color navigator normally, but I did once., but only with version 6, with my earlier CG243W. That is my disclaimer!

With presets 1-7 I am NOT sure if colornavigator can calibrate YOUR monitor internally using the EIZO inbuild LUTs. 2 through 7 are factor presets in any case.

The CAL presets definitely lets the colornavigator software drive the eizo onboard LUTs to calibrate monitor internally instead of using the video card.

On my CG243W I have to use CAL3 because that is hard wired to the Display port , CAL1, CAL2 are hardwired to vga and hdmi inputs.

I would only use preset 2 thru 7 for NON color managed apps. e.g. you have a JPG saved in AdobeRGB, and you want to use an app/computer combination that is NOT color managed.
i.e. using those presets WITHOUT an ICC file and CMM the display will better match the colorspace. Could be usefull, especially the sRGB profile if you using the monitor with computer/app that has no color management. I can think of other use cases, but for your application NO.

For your use case., IF using color naviator callibrate AND profile, (though I think software does not make any distinction) using one of the CAL options or all three. You could use more than one. I use two, one for working in the day, and one when my room is artificially lit. (different WP, brightness and gamma). But I achieve this slightly differently. I don’t use color navigator so have to use the Video card to do the calibration.

I also avoiding using gnome color manager, which for ME does NOT work. I just made sure darktable uses the profile.

ArgllCMS is much more powerfull than collornavigator, e.g. you can for example profile the printer you are using, but that is for another day!

I would stick with what your have for the moment, try and get your calibrate and profile for monitor done and working with Darktable. When you got that working, try to some softproofing. The supplied profile from the printer shop maybe helpfull. That profile your posted PSO Coated v3 ICC profile crashed my darktable when I tried to use for softproofing. When I tried it for the second window it just ignored it. If your set on using it , you could try using other tools. But maybe I downloaded the wrong one. The one I got was designed for CMYK input, I think.

EDIT. Actually the one I download is a device link profile, which my version of Darktable can’t use, and Rawtherepee its the same. See my other thread.

Does Darktable support device linked ICC?

I created a device linked ICC profile from ArgyllCMS for softproofing. I tried to find somewhere in darktable to add this. I tried softproofing but I think just works for a normal ICC device profile. Is there some easy way do this? This is an example of how I created the device linked profile. #Argyll Usage Scenarios I understand that LittleCMS can work with device linked profiles, as of course ArgylCMS and other tools like photoshop etc. EDIT: this also applies to Rawtherapee and solution…

[KarlMagnusLarsson (Magnus Larsson)]

Hello @boredphoto,

@boredphoto

y default darktable is using the following export profile:

When I export the images I use the default image settings in the Export module:

With image settings you get the export profile set in module output color profile. That is sRGB in this case.

@boredphoto

I’m wondering if there will be any benefit exporting the pictures using a different profile.

I think there is a benefit to use a large gamut profile for archiving and as a baseline for further editing. I use Adobe ProPhoto RGB (non linear, i.e., gamma not equal to 1) from RawTherapee called RTv4_Large. The file is here: RawTherapee/rtdata/iccprofiles/output at dev · Beep6581/RawTherapee · GitHub

I also archive in 16 bit integer TIFF. This is required since Adobe ProPhoto RGB (RTv4_large) has large gamut and 8 bits could led to to large color gamut steps.

The camera sensor is capable of capturing a large color gamut. I prefer to collect all of that. I commit to a smaller color gamut only as last step: sRGB for Web and AdobeRGB for pinting.

@boredphoto

Thanks @KarlMagnusLarsson I recalibrated using your suggestion. As I wrote below in another answer the difference are invisible to my eyes but I understand why this is better.

Certainly. This is true. sRGB is a very useful color space. The optimum is to cover with a color profile with smallest possible color gamut, but which still covers the gamut of the scene. Most of my captures fit in sRGB. However, if I do macro photo of flowers and insects, or when I take pictures of artwork, then I do get colors that are outside sRGB and I benefit from a larger color profile, that is if I convert such a capture from bigger profile to sRGB I notice a color change.

The color profile of all naturally occurring colors is called Pointers gamut: Color Gamut | Cinepedia

[betazoid (Anna)]

Oh man when I landed here in 2018 or so I was one of the very few people who had a wide gamut screen (and could test color management with wide gamut). Now everybody has Eizos…

[KarlMagnusLarsson (Magnus Larsson)]

…and how lovely it is.

[mosaster (Alex M)]

Guys @KarlMagnusLarsson @boredphoto Thank you for posting, this thread is practical guide for DT color management!

[priort (Todd Prior)]

@boredphoto

I’m wondering if there will be any benefit exporting the pictures using a different profile.

Its a matrix profile (ie the default srgb profile) with no lookup table so you can change the rendering intent all you like and you will get perceptual render no matter what, which is not a bad thing but often I have found relative rendering is a better look for some edits…it adds a bit of punch… you can download one of the other srgb profiles at color.org ( sRGB profiles ) there are 3 you can try… one is a slightly modified version of the srgb standard… one is called appearance and it is supposedly very good to maintain your image look when dropping from wide gamut to smaller…so perhaps like the drop we do from working to output for a export to srgb and one is called perceputal srgb but it has all the rendering intents and actually the effect of the relative render is stronger… You can copy them to the \color\out folder of your config directory and experiment with them … they can be an option… As of late when I have posted an image to the forum I have often done so with both versions just for comparison…