Monitor profiles and deep shadow tonality

Hi, here’s a question for people that see almost all the patches: do you normally print your pictures? I ask because I see about 16-17 patches (depending on the illumination), and that is because I wanted my monitor to give me a good preview of my prints. If I set it brighter (or better, with a lower gamma), all my prints will turn out too dark. BTW, I use an online service for printing which wants pictures in sRGB. In this respect, I found this piece of documentation of displaycal quite relevant and helpful:

So if you are displaying images encoded to the sRGB standard, or displaying video through the calibration, just setting the gamma curve to sRGB or REC 709 (respectively) is probably not what you want! What you probably want to do, is to set the gamma curve to about gamma 2.4, so that the contrast range is expanded appropriately, or alternatively use sRGB or REC 709 or a gamma of 2.2 but also specify the actual ambient viewing conditions via a light level in Lux, so that an appropriate contrast enhancement can be made during calibration. If your instrument is capable of measuring ambient light levels, then you can do so.

I rarely print, but I DO print sometimes.

Prints are my #1 end goal, so my setup reflects this. Generally going from adobe rbg to sRGB for web is OK and is easier than going the other way.

On my mobile device, I see 15 patches; on the laptop, I see 20, or 22 at max brightness. Both have sad screens that aren’t profiled and Firefox with the color management settings enabled.

(From above: I can see about 23 patches in a profiled monitor.)
With profile turned off, i.e. when running the monitor in its native mode, I can see about 14 patches.

Have fun!
Claes in Lund, Sweden

So, answering some of the questions:

  • I do see all the shadows in the night shot just fine, at least when looking at it without the white background. Here on pixls it’s a little harder but still possible.

  • I do see all the 25 grey patches.

  • To show how little monitor profiles changed for me, here are both the one I made on 25.06.2013 and 13.09.2017. The old one was made with the X-rite software on Windows and the VCGT part uploaded into the monitor, the new one was made following Pascal’s blog post. That’s how I have been creating profiles for other monitors for years.

DELL U2413 - 25.06.2013.icc (9.4 KB)
DELL U2413 - 13.09.2017.icc (2.2 KB)

The procedure in Pascal’s blog post is the same procedure I’ve been following for a long time, except I’ve always skipped the calibration step (the colprof step) and profiled my monitor using its native TRC and color temperature) - the only calibration I’ve been doing is to set the monitor brightness to something around 64cd/m^2. My profiles have always had the same shape xicclu curve as your profiles, except the color channels were split.

Recently I’ve been experimenting with using dispcal to calibrate my monitor to have a neutral gray axis, so non-color-managed parts of the desktop will look neutral gray if their corresponding colors are supposed to be gray, such as the new GIMP-2.9 themes. My goal is to make a profile that:

  • Looks as neutral and also as smooth as possible up and down the gray scale.

  • Shows low or zero chroma values - preferably well under LCH “1” - when using GIMP’s screen “eyedropper” to color pick from the screen itself. I’m not sure exactly how this screen “eyedropper” works, but results do change as the installed system profile is changed, and the picked colors cohere with what my eyes are seeing.

It seems curious to me that using dispcal to calibrate and also at the same time make the monitor profile (using the “-o” switch: Argyll Usage Scenarios) produces a profile without that characteristic downward hook at the x-axis of the xicclu curve. Instead the xicclu curve is very close to a straight line, at least if the requested gamma is close to the native gamma reported by dispcal using the “-R” switch.

However, despite the straight-line xicclu graph, the colprof “one step calibrate and profile” monitor profile that I made last night, when black point compensation is turned on in GIMP, seems to “screen color pick” very close to the actual LCH “Lightness” values, which is a nice thing. Here’s a screenshot of the xicclu curves:

I haven’t thought this hard about monitor profiles or spent so much time trying different ways to profile the monitor, for many years. Sigh.

About “installed system monitor profile”: what I mean by “installing a system monitor profile” is using “dispwin -I whatever-filename-the-selected-monitor-profile-has.icc”, or else the equivalent process using displaycal or colord or xicc or oyranos etc. I don’t have colord/xicc/oyranos installed on my system as I find these utilities to be somewhat unpredictable and not friendly to user intervention when the user wants to do something other than what the utility thinks should be done.

In case anyone wants to experiment and doesn’t already know the Argyllcms commands:

  • The command to uninstall a system monitor profile is “dispwin -U whatever-filename-the-selected-monitor-profile-has.icc”.

  • The command to clear the video LUTS is “dispwin -c”.

  • The command to load a calibration file into the video LUTS is “dispwin

  • If the monitor profile has a vcgt tag, there’s no need to also load the calibration file as the “dispwin -I” command also loads the vcgt tag information into the video LUTS.

Yes, thanks! for that link, which prompted me to set my gentoo portage “package.mask” file to not allow Firefox or Thunderbird to be updated again. I’ve been increasingly unhappy with Firefox with each “upgrade” - as @afre noted in another thread these recent updates keep changing settings and functionality. I have Pale Moon installed as an alternative to Firefox, but it doesn’t support the full range of privacy/security add-ons.

1 Like

I was referring to the Chrome interface, which uses that term without explaining where it looks or what it finds there, if anything.

Ah, I thought you were speaking ironically, along the lines of “Why does some Linux software insist on enforcing the use of a system monitor profile that might have been installed without the user even knowing that any such profile had been installed.” But I gave a “straight answer” in case there was anyone reading the thread who didn’t know what “system monitor profile” actually means.

I also assumed - obviously without any good reason other than also assuming the Chrome devs used what might pass for common sense when writing their color management code - that Chrome used the actual system monitor profile if one is installed in Linux, and whatever the equivalent is in other operating systems. Making assumptions is always risky, but the alternative is not saying anything at all :slight_smile:

I want to say “Thank you” for all the feedback on the train tracks image and the 25 gray patches image and regarding xicclu curves and such. I’ve spent a good part of the last couple of weeks experimenting with making different types of profiles for my monitor, and the feedback has been very helpful.

Regarding the 25 gray patches image, I was surprised at the number of people who could see all or nearly all the patches. So I checked to see how the image looks on three uncalibrated and unprofiled displays in our house, in each case displaying the image in Firefox:

  • A low-end Windows 10 laptop: I see all 25 patches, and the background is obviously gray instead of black. Pictures look very washed out on this display.
  • A wide screen LCD TV: I see all 25 patches, and the background looks black.
  • The LCD monitor that came with a small HP Pavilion desktop, running OpenSUSE Tumbleweed: I see 22 patches, and the background looks black. Pictures look pretty good though shadow tonality could be a bit darker.
  • On my own monitor, if I clear the calibration from the video LUTS and use sRGB as the monitor profile, then I see 20 patches.

After experimenting a bit with using ArgyllCMS to make different types of monitor profiles, each time using the same calibration file (using the “multi-step” approach to making a profile that includes a calibration file), the number of patches I could see ranged from 10 to 25, depending on which profile I installed as the system monitor profile. I kept the rendering intent set to “relative colorimetric”, and when viewing the image using GIMP and other image editors, I also selected to not use black point compensation.

Well, probably none of the above is very interesting. The profiles that allowed me to see more than 14 patches (“gamma matrix” profiles made using the “-ag” and “-aG” colprof parameters) also had very large deltas near zero (as reported by “profcheck”), so weren’t exactly accurate profiles, which isn’t surprising given that my monitor’s uncalibrated black level isn’t anywhere near zero.

But here’s something that is puzzling: When using the XYZ LUT profile (the profile with the lowest deltas overall and also near zero), and with black point compensation disabled, and using relative colorimetric intent:

  • GIMP, RawTherapee, Krita, darktable, Photoflow, geeqie (built from git a couple days ago), and digiKam all showed ten visible patches, which is consistent with the actual black level of my monitor.

  • Firefox shows fifteen clearly visible patches and maybe five more “sort of visible” patches. This discrepancy between Firefox and the other image editors and geeqie was also visible in actual photographs and such, but only for predominantly low-tonality images.

I really wish Firefox hadn’t decided to roll their own QMS color management system.

Did anyone perchance check to see how many patches they could see in Firefox vs PhotoShop, or PhotoShop vs various free/libre image editors and viewers, keeping the rendering intent at relative colorimetric and not using black point compensation?

1 Like

Ha, you are wrong!!!

After experimenting a bit with using ArgyllCMS

What setting(s) would be the “optimum”, then?

Have fun!
Claes in Lund, Sweden

That would depend on what your monitor is capable of and also your own particular editing/viewing goals and also on what software you want to use with whatever monitor profile you might make. I’m still experimenting to figure out what works best with my own monitor/goals/software. I’m putting together an article with some test images and procedures/considerations for profiling monitors, but I’m not quite ready to load the article up to my live website.

Speaking of software that you might want to use when viewing images, here are two screenshots illustrating some peculiarities of Firefox/Palemoon (they both seem to handle monitor profiles the same way), vs Google Chrome:

As shown below, when the system monitor profile is a LAB LUT profile, Firefox/Palemoon and Google Chrome both use sRGB (presumably their own built-in version of sRGB) as the monitor profile. I confirmed this by opening the image in GIMP-2.9 and telling GIMP to use sRGB as the monitor profile. The sky is not supposed to be saturated turquoise blue, but rather “normal” blue sky blue:

As shown below, when the system monitor profile is an XYZ LUT profile, Firefox/Palemoon show correct colors, though deep shadow texture is flattened compared to what GIMP-2.9 shows. But Google Chrome shows, um, something else:

The two sets of screenshots above use:

  • Google Chrome Version 63.0.3239.84 (Official Build) (64-bit), with no changes to whatever chrome does by default to color-manage images.
  • Pale Moon 27.4.1 and Firefox 52.5.0 with settings as per Viewing photographs on the web

Obviously Chrome really is picking up on the system monitor profile, else the image in Chrome would look the same in both screenshots. And just as obviously, it’s not doing the right thing for LUT profiles.

Is there a way to tell Chrome to use particular color management settings, such as what Firefox allows using about:config?

1 Like

Thank you.
I presume that your link above points at your not-yet-live-website.
For those who want to read it today, this link is more alive:

Have fun!
Claes in Lund, Sweden
– also known as Santa Claes and Sinterclaes around this time of the year –

Yes, sorry! and thanks! for catching that. I corrected the post, it used to link to my localhost test server (http://localhost/. . .)

The nice thing about writing a “how to” is it forces you to check things carefully. Anyway, here is my write-up regarding making and evaluating monitor profiles:

What type of monitor profile to make, plus test images for evaluating monitor profiles

To quote the introduction: This article is a summary of the results of two week’s worth of experimenting with different ways to calibrate and profile a monitor. The article gives an overview of different types of monitor profiles, screenshots of using DisplayCAL to set the monitor’s color temperature using the monitor’s RGB White level controls, a step by step example showing how to use ArgyllCMS to make a calibration file and then use the calibration file to make a monitor profile, and test images for assessing the useability of the resulting monitor profile.

Anyway, probably the most interesting part of the article for most people would be the test images. While checking various ways to make a monitor profile, at least for my own monitor some profiles showed color casts up and down the gray axis, some showed shadow posterization, and all showed what I’ll call “faux posterization” visible in neutral gray gradients. There are test images for checking for these issues. There’s also a consideration of “how many patches” should be visible in the Twenty-five patches image.

I’d be very interested to know if anyone else sees “faux posterization” and/or color casts along the gray axis.


[quote=“Elle, post:1, topic:5956, full:true”]

The xicclu curve on the left is from a calibration+profile done in one step using just the colprof utility


Hi Elle,
apologies me but how do we can make e profile only with colprof without ti3 file?
My default language did make me miss something ??:roll_eyes:

No, you didn’t miss anything - I miss-typed - thanks! for catching the error. I should have typed “dispcal” instead of “colprof”. Here’s the link to where the documentation explains how to do a calibration+profile in one step using dispcal:

Adjusting, calibrating and profiling in one step.