ICC profile version 2 or 4 and the color management pipeline?

[KLE-France]

So, down the rabbit hole of color management for us!

I'm on a Windows 10, 64-bit operating system with a run-of-the-mill Dell P2414H.

I purchased a ColorMunki Display to calibrate my monitor.

In the preferences of the program delivered with it, you have the choice of ICC profile version 2 or version 4.

It defaults to version 4, but my Googling appears to suggest that version 4 may be problematic in numerous situations. However, I'm also having a hard time finding recent AND reliable info (ironically X-rite's own information is very dated).

Of course, I'm most concerned about all this in Affinity Photo, so, first question:

Do you advise ICC version 2 or 4? Can AP handle both of them (if that even comes into question), or is it better to use the older ICC version 2?

And more largely (second question), is there anything specific that I need to do to make sure that AP is... correctly calling upon the monitor calibration information in the icm file?

I'm asking because I also use RawTherapee for more "in-depth" raw development, and in that program, you have to indicate the monitor's color profile (point the program to the current monitor calibration icm file, so to speak).  I don't see any such thing in Affinity Photo, although I do think Affinity Photo is completely "color managed"(?). So, I suppose there i a third implicite question: How does AP insert itself into the color management pipeline on any given computer?

De excuse me if my terminology is off; I hope everything is understandable and thank you all in advance for your feedback!

[James Ritson]

Hi Kerwin, welcome to the murky world of display profiling and colour management 

Quote

Do you advise ICC version 2 or 4? Can AP handle both of them (if that even comes into question), or is it better to use the older ICC version 2?

Are you using i1 Profiler or something similar? (I believe the ColorMunki software might be the same, just rebranded). I don't use it any more (I use displayCal instead which only generates v2 profiles) but Affinity Photo's colour management system should handle v4 profiles just fine.

Quote

And more largely (second question), is there anything specific that I need to do to make sure that AP is... correctly calling upon the monitor calibration information in the icm file?

Just make sure your custom profile is loaded within the Windows colour management system and that's it. The Affinity apps will automatically colour manage from your document profile to display profile.

The only caveat I would mention is if you were switching between different profiles for whatever reason (perhaps comparing D65 to D55)—whereas on macOS the document view will change accurately, it's been my experience on Windows that you should restart the Affinity apps between display profile changes to ensure everything works as expected. You don't need to worry about this if you're only ever using one profile though.

Quote

I'm asking because I also use RawTherapee for more "in-depth" raw development, and in that program, you have to indicate the monitor's color profile (point the program to the current monitor calibration icm file, so to speak).  I don't see any such thing in Affinity Photo, although I do think Affinity Photo is completely "color managed"(?). So, I suppose there i a third implicite question: How does AP insert itself into the color management pipeline on any given computer?

Yes, the Affinity apps are fully colour managed—we use our own solution to manage the document view or "canvas" as it's called, so it goes from your current document's colour profile to the display profile. The UI is also colour managed, but I believe Windows handles that area.

[Edit] Here's a tldr for brevity: calibrate then profile your monitor, then make sure that profile is loaded within the Windows colour management (the profiler software should take care of this). Run the Affinity apps and everything will be colour managed without any intervention required.

Hope that helps!

[v_kyr]

Isn't the Affinity software LittleCMS based? - Then it shouldn't be a problem using either here.

[James Ritson]

4 minutes ago, v_kyr said:

Isn't the Affinity software LittleCMS based? - Then it shouldn't be a problem using either here.

Yes, in theory it shouldn't be a problem—I'm just basing the answer from my experience at the time having used i1Profiler to generate v4 profiles. I'll edit my post for clarity. There shouldn't be an issue using v4 profiles, but we can't speak for other software that may use different CMS solutions.

[v_kyr]

6 hours ago, Kerwin said:

I'm asking because I also use RawTherapee for more "in-depth" raw development, and in that program, you have to indicate the monitor's color profile (point the program to the current monitor calibration icm file, so to speak).

Related to RawTherapee see here ...

Quote

Monitor

Set the "Default color profile" to the ICC file you generated when calibrating and profiling your monitor. You can have RawTherapee try to auto-detect the profile by using the "Use operating system's main monitor color profile" option. ...

 

Other than that just the general/common Monitor related calibration rules apply, which are independent of the Affinity software ...

Quote

Calibration parameters

The factory defaults for calibrating the monitor are D65 (6500 Kelvin) for the white point (color temperature), gamma 2.2, and a brightness of 120 cd / m². These are usually good starting points, especially since ordinary screens are usually delivered so that they represent sRGB reasonably correct without further settings, ie preset to a white point of 6500 K and a gamma of 2.2. The default setting of wide gamut monitors is often based on Adobe RGB, thus also based on D65 and Gamma 2.2. However, it certainly does not hurt to check in the monitor's hardware menu that the correct color space is set. The better this harmonizes with the target values for the calibration, the less the color space must later be reduced by the color profile and the lower the loss of tone levels.

Which monitors are suitable?

The interaction between image processing or graphics program, operating system, display driver, graphics card, monitor cable and monitor with control is normally designed for a signal with 8-bits per color channel. When calibrating a screen, this makes it difficult to correct because there are no intermediate values available. If, for example, the gamma curve of a color channel is to be corrected via the monitor profile, the given 256 tone levels no longer exactly match the "sag" of the desired curve. The brightness distances from one tone value to the next are smaller in a gamma curve in the dark areas than at the bright end, and with a gamma correction, deviations due to the rounding practically inevitably cause successive tone values to coincide with each other where the curve is flattened, and there, where the curve is steeped, partly torn apart so that originally existing tonal values are partially skipped. In one case, detailing is lost in the depiction, while in the other, the tonal value jumps can be seen as so-called breaks in progressions. However, there is a technical "back door" to prevent such tonal value lost. Then, if the monitor has an internal color table (LUT = look-up table ) with a higher bit depth. A LUT with ten bits per channel has 1024 tone levels from which the calibration picks those 256 closest to the desired values for the desired tone curve. This way, loss of detail and breaks can be avoided; even in the corrected representation, each channel retains 256 distinct tonal values. The catch is that the 1024 possible tonal values can not be addressed directly via an 8-bit graphic signal. So it needs a special controller that allows the calibration software to communicate directly and at the full bit depth available with the monitor hardware to optimize the allocation of tonal values between the more accurate LUT of the monitor and the mostly 8-bit limited graphics signal supplied by the computer make. Exactly this is the beating advantage of hardware calibratable monitors with appropriate software. With normal monitors, which can only be calibrated by software, ie via an ICC color profile, the accuracy of the correction is limited to 8 bits and is subject to the aforementioned errors. At best, a different global gamma preset may be recalled on such a monitor, however, calibration using a meter will not allow individual assignment of higher bit depth tones from the monitor's internal LUT.

Updates for monitor software

Some hardware-calibratable image-processing and proof-reading monitors come with specialized calibration software from the manufacturer. Thus, hardware functions can be used as well as the calibration directly in the monitor LUT with higher color depth.

 

[KLE-France]

Thanks James and v_kyr for this information!

Color management is one of things where the more you know the more you realize you don't know...

But thanks to you guys I'm a couple of steps further along on the pathway.

Happy shooting to you both!