Displays Display Calibration - How Good a Match Can You Get?

So, I've picked up a cheapo Pantone Huey decade-old colorimeter and had a shot at calibrating my desktop and laptop. Both have calibrated, giving me colour matching profiles at 93 and 97 percent of sRGB respectively, but putting the two side-by-side shows that the desktop looks warmer (so is at a lower colour temperature, 'cos colour science is stupid science) and the laptop looks cooler (so is at a higher colour temperature.)

Basically, looking at a white image has a slight yellow cast on the desktop and a slight blue cast on the laptop (relative to each other.)

Now, the two displays couldn't be more different: one's a three-year-old Sharp IPS 13" 1920x1080 thing, while the other's an eight-year-old Philips VA (I think) 24" 1920x1200. Am I just expecting too much to have two very different display technologies colour-matched - or is something screwy with my calibration?

 

Which should be accounted for by the colorimeter results, as it sits on the same side of the mask as I do.

 

As close as I could get, aye - I think the main problem is I couldn't adjust the colours on the laptop pre-calibration like I could on the desktop.

 

I was thinking that, but it seems a shame to ignore the little "adjust the monitor so the bars are in the middle" RGBW calibration step.

I am wondering if the colorimeter is reading right: on that step, both the laptop and the desktop showed the green channel being lower than the others - which I could adjust on the desktop, but had to ignore on the laptop.

Nup - I swapped it out for GNOME's Night Light on the desktop a while back, and that only triggers at night; I disabled Redshift on the laptop when I saw it was overriding the colour correction profile I'd made.

 

Yeah, the thought had occurred. No real way to know without either another colorimeter to compare or a calibrated monitor to test it against!

 

One of those is a lot more likely than the other!

Maybe it's time to start planning a monitor upgrade anyway - this Philips thing wasn't exactly pro-grade when it was new, and it hasn't improved with age.

 

I can get the desktop looking more like the laptop if I set a colour temperature on the monitor of 8200 K, which results in an ICC profile claiming that the white point is 5400 K (?) - and the same issue of the green channel being way below the others in the initial manual calibration stage.

I'm starting to think that the Huey might be a great experiment, but not such a useful tool...

 

Right, hang on, turns out there's a setting or two I should probably have looked at 'ere...



That was set to a whitepoint of "as measured" and a tone curve of Gamma 2.2. Switched to a manual 6500K colour temperature and sRGB tone curve then re-ran the calibration with a manual monitor fiddle to centre the bars (which, this time, has set things to 49 red(!) 100 green and 99 blue) and everything looks a lot colder now. Sadly, it's also taken me further out of the sRGB gamut - I'm only seeing 86 percent coverage post-calibration.



I still don't know if that's just the monitor being old and cheap or the colorimeter being... well, old and cheap. Hell, let's assume both.

EDIT:

Testing using the oh-so-scientific approach of holding the laptop up next to the desktop's monitor and displaying the same images (https://webkit.org/blog-files/color-gamut/) on both, they're looking pretty well matched now - though I still have no idea if the colour is *accurate* or if they're just both equally wrong now. Why is nothing ever easy, eh?

 

Well, things *looked* okay, but when I compared a couple of images to my phone it revealed a greenish cast to the desktop - which is unsurprising, I guess, given that I turned red nearly halfway down.

I'm seeing talk of some colorimeters using filters which degrade over time, so it's entirely possible that the Huey is just too old to be of any use. Bums. Guess now I know why it was so cheap!

 

I used to do the same except with magazines, but recently my stuff in CPC has been coming out super dark - and I wanted to see if the problem was at my end or theirs.

So, I did some further research: turns out that many colorimeters use organic filters which degrade over time - a process accelerated if they're exposed to air, like they are in the Huey design. Additionally, older colorimeters don't understand modern panel backlights (though I'm not sure if my eight-year-old monitor is modern enough for that to be a problem). Put the two together, and that's probably why I'm struggling.

I'mma treat the Huey as an experiment and splash out on a Colormunki Display - apparently it's the exact same hardware as the X-Rite i1 Display Pro except with weaker software and a 30% firmware-enforced wholly-artificial penalty to read speed. As I'm using third-party software anyway and am in no rush, it's worth it to save about £65 off the price of the i1 Display Pro - and both are sealed units with the filters behind glass, so it should last longer than Huey-style open-air colorimeters. The guy who maintains DisplayCAL recommends 'em, so who am I to argue?

 

As I suspected: the green filter on the Huey is shot. Threw the shiny new Colormunki Display at the monitor, and instead of showing the red and blue channels high and the green massively low it showed the red and green channels high and the blue channel low (which fits in nicely with my whole "everything looks too warm" observation.)

The final result, when calibrated to a 6500K temperature (actually measured at 6540K, but what's 40 Kelvin between friends) is this:


That's what 96.49 percent of sRGB looks like, and I don't reckon a TN panel is ever going to get closer than that. Things are also looking a lot bluer now (for obvious reasons), and I reckon I'm going to see a much closer match betwix the desktop and the laptop (once I've thrown the Colormunki at the laptop, anyway.)

 

Calibrated the laptop, too, and things are looking pretty much identical between the two displays now. The laptop's darks are darker, but that's likely because it's a more contrasty display with better viewing angles anyway. The colours, to my untrained eye, now look spot-on betwix the two, which is what I was *expecting* to see when I first started calibrating things.

Oddly, though, DisplayCAL reckons my ancient cheapy Philips monitor handles more of the sRGB gamut (96 percent ish) than my far newer, supposedly high-end XPS 13's Sharp panel (94 percent ish.) I ain't going to quibble over a couple of percentage points, though!