Colour management question

[rvst]

This isn't an affinity related question per-se, but there are a lot of knowledgeable people on this forum and I'll probably get a more coherent answer here than elsewhere.

I took delivery of two EIZO CS2740s yesterday. I calibrated two of the monitor custom settings to a 100cdm2 native gamut with a 2.2 gamma on one and to 100cdm2 sRGB profile with gamut clamping enabled on the other. 

These are the same settings as two of the factory calibrated and built-in profiles and the calibration result is visually indistinguishable from the factory calibrated profiles, so I know the calibrations are good. All the following comments apply both to my created profiles and to the in-built factory calibrated profiles.

I have Colornavigator 7 installed and it appears to be working correctly. That is to say, when I change profiles on the monitor between Native, AdobeRGB and sRGB, the ICC profiles used by Windows for the display profile also change to the correct ICC profile that is associated with that monitor profile. This is done by the Colornavigator tray app. 

I use an NVidia RTX 3070. I've set it in Nvidia control panel to send 32 bit, 10 bits per pixel, full range RGB to the monitor. The monitor confirms on the OSD that this is the signal it's getting. There are no colour adjustments taking place in the Nvidia control panel of course. Color accuracy mode is set to "accurate", so it's not set to bypass the windows display colour transform.  

Now, I load up a file into affinity photo. The file is an RGBA/16 sRGB file. I've set the working space to sRGB, so all the colours in this file fit within the more limited sRGB colour space and it's not being converted into a wider gamut working space.

I would reasonably expect that this file would look the same on my monitor, whether the monitor profile be set to native gamut, AdobeRGB or to sRGB gamut, assuming Windows colour management is working properly. I mean, this is the whole point behind a colour managed workflow, right?

However, it doesn't. If I flip back and forth between the native gamut and sRGB gamut profiles on the monitor, there is a visually obvious difference where the native gamut profile on the monitor shows colours of the sRGB file in the sRGB working space as significantly more saturated than the sRGB profile on the monitor. The is the type of behaviour one would expect from an app that is not colour managed, where it stretches an sRGB gamut to fit the wider display gamut. 

I've even checked with other colour managed apps, not just Affinity Photo, and the behaviour is the same. 

The EIZO support person seems to think this is normal. Am I fundamentally misunderstanding something about colour management workflows here, or is this indeed unexpected behaviour? The EIZO tech's insistence is making me doubt myself now...

[lacerto]

Obsolete.

[rvst]

1 hour ago, lacerto said:

I am not sure if I understood the issue, but if you mean that you get different appearance in color managed sRGB file when switching the monitor color gamut from within a control/app that directly adjusts the hardware, this sounds like a problem of monitor color profile just not "taking" (even if you can see the profile change in the UI color management windows). Does the problem stay even if you reboot?

Yes, correct. A colour managed sRGB file looks totally different on a calibrated wide gamut profile to the calibrated sRGB profile. The effect is as if I'm using a non-colour managed app to view an sRGB file on a wide-gamut monitor: more saturated colours than they should be. 

The monitor is hardware calibrated and there is an associated ICC profile loader that integrates with Color Navigator, the EIZO calibration software. When switching the monitor profile, this profile loader is responsible for loading the associated ICC profile. It looks to me like it's not working properly even though it seems to be associating the correct profile name. This is what I asserted to the EIZO tech too, who didn't agree. And yes, the problem stays after boot.

1 hour ago, lacerto said:

I experience occasionally issues with Windows monitor color management when using multiple monitors or when switching the display resolution, etc. These can normally be fixed by using a calibrator-based profile loader and could perhaps also be fixed by reloading the correct profile using the Windows native color management controls, but sometimes I need to reboot to have the profiles properly loaded and taking effect.  

This does happen with Windows, you're right. Windows colour management profile loading is a bit broken. That's why DisplayCal has their dispcalgui profile loader - I previously used DisplayCal with their profile loader on my old monitors.

 

[rvst]

Found the cause. There's something wrong with the ICC profiles generated by EIZO Colour Navigator. They're garbage. They weren't particularly accurate anyway: calibrating to D65 gave a white point after calibration consistently of around 6700k, so I had to make manual adjustments to get a more accurate calibration.

After manual adjustment I got a perfect D65 whitepoint with delta-E of zero and a very good grey balance and gamma across the board, saved the profile to the hardware and then used Displaycal to profile the calibrated monitor and generate a new ICC profile. 

I'm now looking at the left hand monitor set to the native gamut profile with the same sRGB image up in Affinity Photo and a second view of that same image on the second monitor, this one set on a sRGB profile. There's zero visual difference between the two images, light years from what I was seeing previously. 

So, great monitor. Rubbish calibration software. I've yet to come across any commercial software that has even a tenth of the accuracy and capability of Displaycal. 

[lacerto]

Obsolete.

[thomaso]

11 hours ago, rvst said:

So, great monitor. Rubbish calibration software.

I can't imagine that especially EIZO provides a 'rubbish' software. I used it without issues for years (but switched meanwhile to X-rite hard-/software to calibrate non-EIZO devices.)

Although I am not familiar with the two .icc versions I agree to @lacerto's hint, and I vaguely remember this also has been mentioned some months ago in an Affinity forums thread as being relevant.

EIZO mentions the difference and possible compatibility issues – although they write v4 would be "backward-compatible" (which sounds conflicting with possible incompatibilty to me).

https://www.eizo.com/library/management/color-management_icc-profiles/

Also this site (linked by EIZO) may interest for a v2 / v4 compatibility test: https://www.color.org/version4html.xalter
To me, opening their PDF in the Apple Preview.app shows incompatibility while opening it in APub V1 as sRGB document looks fine for all four test images / profiles.

[rvst]

Thanks @lacerto and @thomaso. You're both right about the ICC v2 vs v4 profiles. I'd come across this years ago and typically have always used v2 profiles. Color Navigator does default to v4 profiles, so I'll test with v2 profiles and see if this yields a better result. Perhaps the v4 profiles are not loading properly (the ones I generated with Displaycal were v2 profiles, which is maybe why they worked better). I'll probably still profile the Colour Navigator generated calibrations with Displaycal though, for the reasons below...

1 hour ago, thomaso said:

I can't imagine that especially EIZO provides a 'rubbish' software. I used it without issues for years (but switched meanwhile to X-rite hard-/software to calibrate non-EIZO devices.)

My other reasons for dissing Colour Navigator: its lack of custom correction matrix support for colorimeters and the rather low number of readings it takes when it does a calibration: I find I have to make multiple calibrations to let it converge on a better solution. Displaycal just does an all round better job, although of course it can't do the hardware calibration, so can only be used to profile an existing Colour Navigator calibration.

On the colorimeter support, I'm fortunate to own two calibration devices, one a i1p2 spectrophotometer and the other a i1d3 colorimeter. Typically, my use case has been to use the i1p2 to create a correction matrix for the i1d3 for the specific screen. You can't do this with Colour Navigator - it uses the device's builtin RG-Phospor spectral correction matrix, which gives a distinct cast and isn't very accurate. When I verify a calibration made with the i1d3 by using the i1p2, it's significantly off (dE > 3) - others have complained about this as well, I'm not the only one to note it. 

So I'm forced to use the i1p2 to actually do the calibration with Colour Navigator. But even then, it doesn't get anywhere close to as good a result as it should. For example, calibrating to D65 consistently yields something around 6650k. And so I have to zero in the target manually, which I can do fairly easily and get a dE of 0 or 0.1, which in itself is huge kudos to the monitor hardware, but it shouldn't be necessary - the monitor can get this level of accuracy, but the software can't. The software should just do more optimisations, with something like a time to accuracy slider to allow the user to control the number of iterations it does.  

Having to use the spectrophotometer to calibrate is non-optimal because it's not as good on the blacks as the colorimeter, it reads much slower and using it to calibrate just kills the lifetime of the light, which I'm reluctant to do since it's a really expensive device. In general, Colour Navigator just feels like a dumbed down piece of software. But, I can understand why this is - it probably best meets the needs of the majority of non-technical users and is good enough, but it's just a bit too dumbed down for me. No different to any of the other commercial calibration software: i1Profiler is worse in my opinion. I'm probably just used to the extremely high level of control that Displaycal gives me and I've been using it for a decade, so the switch to a less capable piece of software bugs me a bit.