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Hi!
First off, thanks for taking the time to read to this post. Any help anyone can give me would be gratefully received!
So I have an ASUS ProArt Display PA27UCX-K which I’m trying to calibrate through Davinci Resolve in order to colour grade a feature I shot last year. I’m actually a Director of Photography not a pro colourist so I’ve been teaching myself what I can about grading – and monitor calibration is one of the areas I’m struggling with…
I’ve read the DisplayCAL documentation and lots of various forum posts trying to work this out for myself, and then (basically because I still don’t know quite what I’m doing) I’ve been trying lots of different settings and generally experimenting with DisplayCAL to try and get the correct calibration. I can’t help feeling like a lot of what I’m reading goes wayyyy over my head! 😀
I’ve really hit a point where I feel like I’m stumbling around in the dark. I keep getting very different results (obviously) so I wondered if any kind hearted DisplayCAL aficionados could just advise me simply on what settings and procedure I should use to get a PROPER calibration.
Some of my calibrations have looked pretty good – but noticing they all look quite different, I’m wondering how I can tell what the CORRECT one is. Does that make sense?
An editor friend of mine here in the UK advised me that I should calibrate to REC709 Gamma 2.4, so I’ve been aiming for that. The film is likely to be screened at various film festivals (FrightFest have already said they would take it). And then they will likely be aiming to get it onto some streaming platforms.
So my first question is – would you all agree that REC709 Gamma 2.4 sounds like the correct calibration target? Or would you guys advise something else?
Furthermore, I have an Xrite i1 Display Pro that came with the monitor. I also have access to a Datacolor Spyder X Elite.
Would either one of these meters be better for the job? Or will they both work fine? And are there any settings I should definitely be using with whichever one you would recommend?
I’ve read quite a lot about loading correction profiles for the different colorimeters, and I’m still not sure that I completely understand this concept. Would my i1 Display Pro already have the proper correction profile loaded into it, as it shipped with the monitor? Or would the Spyder X (either straight out of the box or with a profile loaded) be the better option?
Thanks so much in advance for your help! And please forgive my ignorance. I feel quite out of my depth with this whole calibration topic!
Calibrite Display Pro HL on Amazon SpyderX Pro on Amazon
Disclosure: As an Amazon Associate I earn from qualifying purchases.Some of my calibrations have looked pretty good – but noticing they all look quite different, I’m wondering how I can tell what the CORRECT one is. Does that make sense?
We do not know whioch steps did you follow.
Let’s assume some basic scenario and then add your details.
-Let’s say that you know hoy to set your asus display to native gamut , D65 and 100nit measured with your i1displaypro (i1d3 for short).
If you do not know basic i1d3 operation it’s a very fast & reliable colorimeter for its price, but needs to know a sample of the backlight it is going to read, its spectral power distribution (SPD, power emited by each wavelength). This is stored and shares by community in CCSS text files (spectral colorimeter correction).
Modern widegamut displays are usually WLED PFS or QLED, check https://colorimetercorrections.displaycal.net and find a suitable CCSS file. Set is as colorimeter corerction in displaycal 1st tab.
Play with RGB gains on your display till you get D65 white (6500K/6504K and daylight curve) and 100cd/m2.
This will set your display at desired brightness, desired whitepoint , full native gamut and uncalibrated grey.-Depending on your final task & dedicated HW (like decklink cards or commn GPU card like an nvidia or AMD) you can create a “ICC profile” (+optional grey calibration) that describes display, how it behaves. It’s like a taylor made suit where ypu don’t hide where ypu are fat or thin. True measures.
-Once you have a profile that describes actyual display response you create a LUT3D that reencodes Rec709 gamma 2,4 content to your display colorspace (described by your newly created ICC profile).
-You load the .cube LUT3D file into resolve as described in FAQs (there must be some thread about it, place LUT3D .cube file in some folder and Resolve will see it) and Resolve will input Rec709 video to that LUT3D to get equivalent RGB numbers reencoded in display colorspace
So that is the basic operation. Maybe you skiped some step, IDNK.
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An alternative way for people using common GPU card from nvidia or AMD (no decklinks just regular graphics card) is to create a ICC profile + grey calibration for general use and then additionally create a LUT3D for Resolve work.
Calibrate as a regular monitor for common uses: D65, gamma 2.2 etc…
After calibration DIsplayCAL will load that display profile in OS and you can use Photoshop or other color managed apps expecting see things right (unless rounding errors and all that stuff at 8bit precision).After that you create a LUT3D from that display profile using the same settings described above. Source “Rec709, gamma 2.4”. Target/destination your new display profile, do not load VCGT grey calibration since it will be kept sysrtemwide by DIsplyaCAL due to dislay profile). Then load it into Resolve. That’s all
It does not matter that your display was calibrated to 2.2 gamma for general use, LUT3D will tranform/reencode content so in Resolve video looks 2.4.*****
In Resolve preview icons are not color managed. Also it’s easy to test with 100% saturation R G B C M Y videos in MP4 that gamut limitation to Rec709 was done properly with a visual test.
Hi Vincent!
Wow! Thanks so much for getting back to me in such detail so quickly! I really do appreciate your help! 🙂
Ok… So that’s interesting. I think this is starting to make a little more sense to me now.
-Depending on your final task & dedicated HW (like decklink cards or commn GPU card like an nvidia or AMD) you can create a “ICC profile” (+optional grey calibration) that describes display, how it behaves. It’s like a taylor made suit where ypu don’t hide where ypu are fat or thin. True measures.
-Once you have a profile that describes actyual display response you create a LUT3D that reencodes Rec709 gamma 2,4 content to your display colorspace (described by your newly created ICC profile).
So let me see if I’m getting this right – The actual ‘calibration’ that’s done by DisplayCAL is just a way of measuring the true capabilities and scope of what the monitor can do, and then then the LUT encoding at the end is a way of translating that into whatever you set up on the 3D LUT page?
I didn’t grasp that concept before. I was assuming you had to set what the 3D LUT encoding was when you ran the calibration. But if I understand correctly, you could measure your display (run the calibration) and then encode to more or less anything else? So you could create a LUT for REC 709 G2.2, or REC709 G 2.4 and it would simply scale to what was measured in the calibration? Is that correct?
So one other major complication I have is that (REALLY annoyingly) the joystick button on my PA27UCX monitor fell apart the other day as I was using it. I think there’s a possibility that it was damaged in transit. ANYWAY… It means I can’t really access the OSD menu on the monitor.
Sooo that means I can’t actually manually tweak the RGB gain and brightness/contrast or nits values in the monitor. The monitor comes with the Asus Proart Calibration software, but it doesn’t seem to alllow you to set the target nits, only the D65 colour temperature. 🙁
I’m desperately keen not to get into sending it back to ASUS for repair as I know it will take ages to get done. Very frustarting…
Is there another way of hitting the 100 nit target and the RGB gains without needing to change it physically on the monitor? Like for instance, can DisplayCAL simply do that with the 3D LUT? Or am I out of luck there?
We do not know whioch steps did you follow.
You’re totally right Vincent! Apologies, I should have given you a bit more information about my setup and what I’ve already tried. Sorry about that mate!
So I think I have pretty much followed all the steps you detailed in your response – apart from being able to physically change the RGB gains and the brightness etc on the monitor OSD (as I mentioned above). It may simply be that without that OSD control I’m stuck – and will just have to bite the bullet and deal with ASUS support to get a repair. But I’m really hoping there is another way around it!
Generally speaking, I’ve tried lots of calibrations and played around with lots of the different options in DisplayCAL to see if I could get a sense of what they do. Before I get into that though, let me just explain a bit more about my setup:
So I have my PA27UCX-K hooked up to my Blackmagic UltraStudio 4k Mini. I have a 12G SDI cable going from the UltraStudio 4k to a Blackmagic Design Micro Converter BiDirectional SDI/HDMI 12G box, and then run HDMI out of there to the monitor. Blackmagic tech support pointed out to me that this is a bit of a weird way of doing it, but again it was something someone recommended to me as a way to go as I have a seperate Mac Laptop running ScopeBox 4. If I apply the 3D LUT monitor correction (after say, running DisplayCAL) on in the Resolve Color Management tab, it applies it to the ScopeBox feed too and the scopes come out with the monitor correction applied (which I’m told I don’t want). So I upload the 3D LUT for JUST the monitor correction on the BiDirectional convertor and then it applies it ONLY to the PA27UCX-K, whilst keeping ScopeBox clean.
Basically, I’m using the BiDirectional Converter as a cheap LUT box… 😉
Does that all make sense? It’s probably a totally mental way of doing it so again if anyone can see an easier way of doing it without spending anymore money on gear (I’ve already spent a small fortune on this setup as it is) then please do let me know! 🙂
So what I’ve been trying in DisplayCAL —
I’ve been using the ‘Video 3D LUT for Resolve (D65, REC. 709 / REC. 1886)’ in the settings drop down as my starting point, and then running the calibration through the UltraStudio 4k Mini via the Portrait Displays Calman connection in Resolve.
In DisplayCAL –
On the Display and instrument tab I’ve mostly used:
Instrument – i1 DisplayPro, ColorMunki Display
Mode – Refresh (generic)
White and black level drift compensation – off
Display update delay – 1000ms
Settle time multiplier – unchecked
Full field pattern insertion – unchecked
Output Levels – usually leave Auto. Is that correct?
Correction – I did find this correcction a while back using the page you linked to above:
“ASUSTek COMPUTER INC PA27UCX (i1 Pro 2).ccss”
Does that look like it would be worth using?
On the Calibration tab:
I’ve tried lots of variables here, but again, not sure exactly which I should be using.
For example, if I’m looking for 100 nits, should I be setting the White level to Custom and setting 100 cd/m2?
On the profiling tab:
Generally left this alone. Sometimes for quick testing I’ve set the amount of patches quite low just to see if I’m roughly in the ballpark without having to wait ages for the calibration to finish.
On the 3D LUT tab:
Source Colorspace – REC709 ITU-R BT. 709
Tone curve – Rec 1886 — Gamma 2.4 — Absolute — Black output 0% — Apply calibration (vcgt) checked ‘on’
Gamut mapping mode – Inverse device-to-PCS checked ‘on’ — PCS-to-device ‘off’
Rendering intent – Absolute colorimetric with white point scaling
3D LUT file format – IRIDAS (.cube)
Input and output encoding – Full range (again… not sure if this is right??)
3d LUT resolution – 33x33x33 (because my BiDirectional SDI/HDMI 12G converter can only take 33 point cube LUTs)
I’ve not really played around with the verification tab much. But am I right in assuming that this allows you to test the final calibration you have set on the monitor to see if it’s correct? So could I use this to measure whether I’m actually hitting REC709 D65 @ 100nits after the calibration and 3D LUT generation?
Sorry for the lengthy response! And honestly, THANK YOU again so much for your help!
Hi Vincent!
Wow! Thanks so much for getting back to me in such detail so quickly! I really do appreciate your help!
Ok… So that’s interesting. I think this is starting to make a little more sense to me now.
-Depending on your final task & dedicated HW (like decklink cards or commn GPU card like an nvidia or AMD) you can create a “ICC profile” (+optional grey calibration) that describes display, how it behaves. It’s like a taylor made suit where ypu don’t hide where ypu are fat or thin. True measures.
-Once you have a profile that describes actyual display response you create a LUT3D that reencodes Rec709 gamma 2,4 content to your display colorspace (described by your newly created ICC profile).
So let me see if I’m getting this right – The actual ‘calibration’ that’s done by DisplayCAL is just a way of measuring the true capabilities and scope of what the monitor can do, and then then the LUT encoding at the end is a way of translating that into whatever you set up on the 3D LUT page?
No, displaycal calibrates grey, if requested to do so. It is what all generic HW in GPUs can do, load grey calibration (color of grey & gamma).
Once grey is calibrated & loaded (if you requested it) DisplayCAL profiles display = measures how display behaved (with optional grey calibration loaded)With display behavior stored in an ICC profile color managed apps know how to transofrm colors, like AdobeRGB TIFF, sRGB JPG and such… but most video edition apps do not use it.
What some video edition apps do is to “crystalize” a FIXED color transform, a LUT3D from colorspace A (content) to B (display) and nothing more.
Note this approach is different form ICC color managed apps where app computes on the fly from ine ICC profile to anotehr ICC profile, that’s why I said “crsytalized transform”, just ONE transformation.I didn’t grasp that concept before. I was assuming you had to set what the 3D LUT encoding was when you ran the calibration.
It CAN do that… if you can load it inside your monitor. but it will do the same.
Imagine that you have an Eizo CG2700X with LUT3D support. You use Colornavigator software to calibrate to native gamut D65 100nits 2.2 for general photo use.
Display *is calibrated* = it behaves as you requested, D65, true neutral grey without colors in grey ramp, 100nit, 2.2gammaNow you measure how it behaves (and since it is a very good display it will behave amost as an ideal display, one described with a matrix ICC profile) and store its actual behavior in some ICC profile (XYZLUT, a 3d mesh).
Then you create a LUT3D as instructed to simulare Rec709 gamma 2.4
Then you load it into CG2700X harware LUT3d using color navigator app.
NOW with LUT3D loaded display is calibrated to D65, rec709, 100nit gamma2.4 = It behaves as an ideal rec709, d65, 100nit, et ceteraSome displays/some software allow to simulate some colorspace without a LUT3D, it uses a lut-matrix-lut. Maybe yours is one of those, IDNK.
This lut-matrix-lut can simulate rec709 but it assumes perect ideal additive behavior in display. It may be true for Eizo CG or CS models but as a general rule won’t expect it to work aon any monitor.
THis is equivalent to profile in displayCAL using a “single curve + matrix” profile type = idealized behavior of display intead od XYZLUT profile (3dmesh).
For general photo use ***IF*** display is good behaved we use singe curve matrix porfiles, to avoid some ugly rounding errors.When you choose to simulate sRGB or Rec709 on VENDOR SOFTWARE, like Eizo’s Color navigator, it uses the simplifiex lut-matrix-lut even if display has LUT3D
Why? because a LUT3D need data from a 3dmesh (huge set of patches)… if you do not have taht amout of measurents it will be interpolated from ideal behavior… and that’s identical to lut-matrix-lut approachBut if I understand correctly, you could measure your display (run the calibration) and then encode to more or less anything else? So you could create a LUT for REC 709 G2.2, or REC709 G 2.4 and it would simply scale to what was measured in the calibration? Is that correct?
Exactly,
profile display, then create whatever FIXED/CRYSTALIZED color transforms as you want…as long as simulated colorspace fits inside display gamut.
If it does not fit (liek Rec2020) it will clip (rel/abs colorimetric intent) or will deform content (percetual) to keep track of gradients at the cost of in gamut accuracy.So one other major complication I have is that (REALLY annoyingly) the joystick button on my PA27UCX monitor fell apart the other day as I was using it. I think there’s a possibility that it was damaged in transit. ANYWAY… It means I can’t really access the OSD menu on the monitor.
Asus has HW calibration app for some models but usually it was very disapointing: wrong colorimeter corrections, low opoctions, bad results… but you may try.
Sooo that means I can’t actually manually tweak the RGB gain and brightness/contrast or nits values in the monitor. The monitor comes with the Asus Proart Calibration software, but it doesn’t seem to alllow you to set the target nits, only the D65 colour temperature.
I’m desperately keen not to get into sending it back to ASUS for repair as I know it will take ages to get done. Very frustarting…
Is there another way of hitting the 100 nit target and the RGB gains without needing to change it physically on the monitor? Like for instance, can DisplayCAL simply do that with the 3D LUT? Or am I out of luck there?
DisplayCAL cannot access propietary APIs in thos displays, but if it has DDC/CI (and it was enabled before you broke monitor button) you can try Xrite i1Profiler, the software that comes with colorimeter i1d3. That will set your display to native gamut D65, 100nits and create a profile with grey calibration to gamma 2,2… i the same way as DisplayCAL
But Xrite software has a limited amount of colorimeter corrections, no QLED or WLED PFS (adobeRGb flavor). You can “forge” and EDR and replace one of the original ones. Search a CS2731 thread started by Midas, of if you know that your asus is a WLED PFS phosphor you may try CS2731 EDR made by Start Pointon (a forged version of Xrite RG_phpshor/GB-LED EDR with WLED PFS data).
So without OSD buttons DDC/Ci by Xrite i1Profiler if your best chance.
DisplayCAL can correct white color while grey calibration, but it will be done as if whiet is one of the greys, limiting 1 or 2 channel max output and droping contrast.
If this EDR editing stuff sound too much complicated you can try one of the bundled corrections in Xrites i1Profiler and the let DIsplayCAL profile or LUT3D correct it with measurements with the “good corerction”. A reasonable 6dE whitepoint correction can be done without loosing a signifcative amount of contrast.
We do not know whioch steps did you follow.
You’re totally right Vincent! Apologies, I should have given you a bit more information about my setup and what I’ve already tried. Sorry about that mate!
So I think I have pretty much followed all the steps you detailed in your response – apart from being able to physically change the RGB gains and the brightness etc on the monitor OSD (as I mentioned above). It may simply be that without that OSD control I’m stuck – and will just have to bite the bullet and deal with ASUS support to get a repair. But I’m really hoping there is another way around it!
Generally speaking, I’ve tried lots of calibrations and played around with lots of the different options in DisplayCAL to see if I could get a sense of what they do. Before I get into that though, let me just explain a bit more about my setup:
That is a different appoach:
So I have my PA27UCX-K hooked up to my Blackmagic UltraStudio 4k Mini. I have a 12G SDI cable going from the UltraStudio 4k to a Blackmagic Design Micro Converter BiDirectional SDI/HDMI 12G box, and then run HDMI out of there to the monitor. Blackmagic tech support pointed out to me that this is a bit of a weird way of doing it, but again it was something someone recommended to me as a way to go as I have a seperate Mac Laptop running ScopeBox 4. If I apply the 3D LUT monitor correction (after say, running DisplayCAL) on in the Resolve Color Management tab, it applies it to the ScopeBox feed too and the scopes come out with the monitor correction applied (which I’m told I don’t want). So I upload the 3D LUT for JUST the monitor correction on the BiDirectional convertor and then it applies it ONLY to the PA27UCX-K, whilst keeping ScopeBox clean.
Basically, I’m using the BiDirectional Converter as a cheap LUT box…
Does that all make sense? It’s probably a totally mental way of doing it so again if anyone can see an easier way of doing it without spending anymore money on gear (I’ve already spent a small fortune on this setup as it is) then please do let me know!
So what I’ve been trying in DisplayCAL —
I’ve been using the ‘Video 3D LUT for Resolve (D65, REC. 709 / REC. 1886)’ in the settings drop down as my starting point, and then running the calibration through the UltraStudio 4k Mini via the Portrait Displays Calman connection in Resolve.
since you ar not using a common GPU byt a decklink. In order to do the Xrite i1Profiler stuff you will need to plug it to a common GPU, use DDC/CI to calibarte whietpoint & brightness and then plug it again to blackmagic GPU and do the DIsplayCAL part.
In DisplayCAL –
On the Display and instrument tab I’ve mostly used:
Instrument – i1 DisplayPro, ColorMunki Display
Mode – Refresh (generic)
White and black level drift compensation – off
Display update delay – 1000ms
Settle time multiplier – unchecked
Full field pattern insertion – unchecked
Output Levels – usually leave Auto. Is that correct?
IDNK how your blackmagic & monitor are configured. IDNK if they where configured to limited or full of how good is displaycal detecting it since i use it will full range signal link in monitor-gpu.
Correction – I did find this correcction a while back using the page you linked to above:
“ASUSTek COMPUTER INC PA27UCX (i1 Pro 2).ccss”
Does that look like it would be worth using?
On the Calibration tab:
I’ve tried lots of variables here, but again, not sure exactly which I should be using.
For example, if I’m looking for 100 nits, should I be setting the White level to Custom and setting 100 cd/m2?
On the profiling tab:
Generally left this alone. Sometimes for quick testing I’ve set the amount of patches quite low just to see if I’m roughly in the ballpark without having to wait ages for the calibration to finish.
On the 3D LUT tab:
Source Colorspace – REC709 ITU-R BT. 709
Tone curve – Rec 1886 — Gamma 2.4 — Absolute — Black output 0% — Apply calibration (vcgt) checked ‘on’
with a limited contrast display 2.4 relative, IDNK if you asus has some FALD feature.
Gamut mapping mode – Inverse device-to-PCS checked ‘on’ — PCS-to-device ‘off’
Rendering intent – Absolute colorimetric with white point scaling
3D LUT file format – IRIDAS (.cube)
Input and output encoding – Full range (again… not sure if this is right??)
3d LUT resolution – 33x33x33 (because my BiDirectional SDI/HDMI 12G converter can only take 33 point cube LUTs)
I’ve not really played around with the verification tab much. But am I right in assuming that this allows you to test the final calibration you have set on the monitor to see if it’s correct? So could I use this to measure whether I’m actually hitting REC709 D65 @ 100nits after the calibration and 3D LUT generation?
Sorry for the lengthy response! And honestly, THANK YOU again so much for your help!
“ASUSTek COMPUTER INC PA27UCX (i1 Pro 2).ccss”
Does that look like it would be worth using?
I would say no since it is simulating rec709 instead of native gamut. ArgyllCMS creator says it won’t make such huge error… but i would try other Asus PA/PG QLED displays which have a native gamut CCSS, for example PA32UCG
Very likely that all use the same QLED backlight. If in doubt plot them and see if the peaks are placed in the same wavelengths.
Apologies Vincent – I’m away filming for a few days (doing my proper job 😀 ) so I’m sorry for not getting back to you yet but I’m not actually with the monitor at the moment.
I’m back next week so I’ll pick this up again then and investigate further based on your advice.
Thanks again so much mate. 🙂
Hey Vincent…did you ever sort this out? I’m doing the same thing with the UltraStudio Monitor 3G and Resolve.
Hey Vincent…did you ever sort this out? I’m doing the same thing with the UltraStudio Monitor 3G and Resolve.
IDNK what you ask for, Max is the one who owns that Asus display, IDNK if he did all the process as instructed.
Hey chaps!
Apologies for letting this thread go dead for so long. I ended up working and before you know it, almost a whole bloody year has gone by!
I did in the end decide I didn’t really have a choice but to bite the bullet and send my PA27UCX back to Asus to get the joystick repaired. Some months and much heart ache later (hahaha dealing with Asus tech support and repairs has been… errr… fun) I’ve finally got a monitor I can access the OSD on (yay…!)
So I’m picking this back up again as I still can’t seem to get this damn thing to pass the verification check for REC709 Gamma 2.4.
Vincent – I tried that PA32UCG CCSS file you recommended. I’ve attached the verification report from that calibration. I’m only doing super fast sets of patches for speed testing to see if I’m vaguely in the ballpark, but even these are showing it being wayyy off.
The monitor has a bunch of different modes within the OSD that you can set it to, for example Standard, REC2020 , sRGB, Adobe RGB, DCI-P3, DICOM, REC 709 etc, as well as a couple of HDR ones (again including an option for PQ 2020). I’ve been setting it to REC 709 Gamma 2.4 for the calibrations. I’m presuming that’s right? You mentioned native gamut a lot before when you were helping me with this. Is that a bit like native ISO on a camera? As in there will be a true native display gamut and all then these other options are just artifical permutations of that native gamut? Do I have that right? And if so, how do I find out what this monitor’s ‘native’ is?
There must be an easy answer to this. So far my experience of calibrating this monitor has been maddening. 😀
My old HP-LP2475w calibrates fine and passes the check with flying colours. I just don’t see how I can get this bloody Asus monitor to do the same.
Is it likely this is still down to not having the correct CCSS file for the monitor?
Thanks again for all your help with this (now year long…) thread!
Max
Damn. Nice monitor. It’s supposed to have hardware calibration? If so, you should probably use the tools that came with it.
What’s your use case for the monitor and the rec709 2.4? Your use case will determine whether it’s better to calibrate the rec709 mode or the native mode and that will determine where to go from here. Vincent will probably be more help here, but I can fill in some gaps and help “translate” a bit.
You have the right idea about native gamut being the true gamut of the monitor. All the other gamuts are artificially created by restricting that gamut. I can’t find any info on your monitor’s native gamut. Maybe Vincent will know.
Again, if the monitor came with calibration tools, you should use those
Hey Old Man (loving the name btw 😀 )!
Thanks for offering to help mate! I really appreciate it!
Well it would be a nice monitor, if I could ever be certain it was calibrated hahaha! 😀
So the use case for REC709 Gamma 2.4 is that I am using it to colour grade various projects I have shot myself in Davinci Resolve (I’m a director of photography by profession). REC709 G2.4 seems to be the widely recommended standard to calibrate to for the sort of work I do. The last film I graded (on my old monitor) at Rec709/2.4 screened during Frightfest on the giant ‘Superscreen’ at Leicester square in London – and it looked great. So I’m thinking I will definitely stick to that for my needs. 🙂
Btw – do you know if I’m correct in thinking that I should be using Gamma 2.4 ‘Absolute’ rather than relative? I’m also a little confused about what the difference is between that and Rec. 1886. I did a fair bit of reading about this and I’ll be honest… it went mostly over my head. I’m wondering if that is likely to make much difference? Would you happen to know?
So I have had mixed success with the Asus Proart calibration software that came with the monitor. Most of the time, I found it crashed during the calibration and refused to finish.
I did however manage to get it to complete last night for the first time in ages. I then tried running the verification on Displaycal on that Asus calibration (set to Rec709 / Gamma 2.4 Absolute), and it was wildly off. But again, I’m not even sure if what I was doing there in checking it makes sense, as I’m still not sure at all that I have the right CCSS and wasn’t sure too if the verification refers to the LUT created in Displaycal?Do you get what I mean?
Presumably, if the probe needs the CCSS to understand what back light its looking at for a calibration, shouldn’t it need the same information to correctly assess the verification? Or have I misunderstood that?
Thanks again for jumping in on this Old Man! Really appreciate your input!
Hey chaps!
Apologies for letting this thread go dead for so long. I ended up working and before you know it, almost a whole bloody year has gone by!
I did in the end decide I didn’t really have a choice but to bite the bullet and send my PA27UCX back to Asus to get the joystick repaired. Some months and much heart ache later (hahaha dealing with Asus tech support and repairs has been… errr… fun) I’ve finally got a monitor I can access the OSD on (yay…!)
So I’m picking this back up again as I still can’t seem to get this damn thing to pass the verification check for REC709 Gamma 2.4.
Vincent – I tried that PA32UCG CCSS file you recommended. I’ve attached the verification report from that calibration. I’m only doing super fast sets of patches for speed testing to see if I’m vaguely in the ballpark, but even these are showing it being wayyy off.
I do not remember what was your problem
The monitor has a bunch of different modes within the OSD that you can set it to, for example Standard, REC2020 , sRGB, Adobe RGB, DCI-P3, DICOM, REC 709 etc, as well as a couple of HDR ones (again including an option for PQ 2020). I’ve been setting it to REC 709 Gamma 2.4 for the calibrations. I’m presuming that’s right? You mentioned native gamut a lot before when you were helping me with this. Is that a bit like native ISO on a camera? As in there will be a true native display gamut and all then these other options are just artifical permutations of that native gamut? Do I have that right?
All colors a (RGB) display can show are a linear combination or native primaries. For example sRGB mode has 3 simulated primaries (less saturated)
Rs = K11 * NativeR + K12 * NativeG +K13 NativeB
Gs = K21 * NativeR + K22 * NativeG +K23 NativeB
Bs = K31 * NativeR + K32 * NativeG +K33 NativeBAnd if so, how do I find out what this monitor’s ‘native’ is?
Usually Standard or “Custom color” or “User color” modes have native primaries.
The other modes have less or equal saturated primaries and Rec2020 is just a map where display translated “in gamut” colors to panel native (liek when in Photoshop fully color managed you try to render the visible colors of an AdobeRGB image in an sRGB monitor, all in gamut colors will render with its actual color).
There must be an easy answer to this. So far my experience of calibrating this monitor has been maddening. 😀
I do not remember what was your problem. If your problem is that you cannot find a suitable colorimeter correction that gives you a calibrated white that looks white, two options, not exclusive:
-rent an spectrophotometer and create a colorimetr cotrrection, share CCSS with community
-visually match that Asus whitepoint to some “reference display”, but if you do this you cannot create absolute colorimetric LUT3D in Resolve, you must use relative (or another more complex trick simulation an alternative rec709 version with another white, but let’s keep it simple for now). If you use abs colorimetric to Rec709 with D65 white it will undo your visually matched white.My old HP-LP2475w calibrates fine and passes the check with flying colours. I just don’t see how I can get this bloody Asus monitor to do the same.
It is a WG CCFL, if you are not using that colorimeter correction white is wrong (excluding observer metameric failure)
Is it likely this is still down to not having the correct CCSS file for the monitor?
Thanks again for all your help with this (now year long…) thread!
Max
Hey Old Man (loving the name btw 😀 )!
Thanks for offering to help mate! I really appreciate it!
Well it would be a nice monitor, if I could ever be certain it was calibrated hahaha! 😀
So the use case for REC709 Gamma 2.4 is that I am using it to colour grade various projects I have shot myself in Davinci Resolve (I’m a director of photography by profession). REC709 G2.4 seems to be the widely recommended standard to calibrate to for the sort of work I do. The last film I graded (on my old monitor) at Rec709/2.4 screened during Frightfest on the giant ‘Superscreen’ at Leicester square in London – and it looked great. So I’m thinking I will definitely stick to that for my needs. 🙂
I do not remember if we talked about this but usually you keep monitor in native gamut + desired white and then compute a LUT3D to whatever colorspace you want to simulate.
If asus HW calibration software was reliable you may truy to simulate Rec709 directly with a HW calibration slot but this does not seem that case.
Btw – do you know if I’m correct in thinking that I should be using Gamma 2.4 ‘Absolute’ rather than relative? I’m also a little confused about what the difference is between that and Rec. 1886. I did a fair bit of reading about this and I’ll be honest… it went mostly over my head. I’m wondering if that is likely to make much difference? Would you happen to know?
If you plot “instant gamma value” vs RGB input, a 2D grapth, Rec1886 depends on display black point, on its luminance. Hence resulting gamma is not the same with a high contrast VA TV 5000:1 than with a 1000:1 IPS monitor without FALD.
On a hgh contrast display ot looks like 2.4 in a 2d plot. On a low contrast display it looks more to 2.2 with lithter (washed) grays so on a 2000-1000:1 IPS it’s easier to aim to 2.4 relative than aiming to Rec1886.
By definition, google ITU 1886
So I have had mixed success with the Asus Proart calibration software that came with the monitor. Most of the time, I found it crashed during the calibration and refused to finish.
It should have several EDR (binary format CCSS that can be converted to CCSS with ArgyllCMS command line tool oeminst). It has some PFS/KFS, it has a QLED miniled.. etc, try one of these but AFAIK theu should be closer to standard CCSS pack if you add that PG32 AdobeRGB QLED you mentioned above.
I did however manage to get it to complete last night for the first time in ages. I then tried running the verification on Displaycal on that Asus calibration (set to Rec709 / Gamma 2.4 Absolute), and it was wildly off. But again, I’m not even sure if what I was doing there in checking it makes sense, as I’m still not sure at all that I have the right CCSS and wasn’t sure too if the verification refers to the LUT created in Displaycal?Do you get what I mean?
Presumably, if the probe needs the CCSS to understand what back light its looking at for a calibration, shouldn’t it need the same information to correctly assess the verification? Or have I misunderstood that?
Thanks again for jumping in on this Old Man! Really appreciate your input!
For your use case, I’d use the Asus software to calibrate the rec709 mode of the monitor and then use that. I assume the Asus software has a verification mode? As long as it passes verification there, don’t worry about Displaycal. It will probably pass Displaycal too. It’s just a matter of getting the right verification settings, which can be confusing.
Rec709 2.4 is a safe bet and I would think most theaters know how to handle it. I believe most theaters natively display in DCI-P3 (2.6) though, so once you’re comfortable, you might want to try that (although I think you’re supposed to grade in a cinema-style grading room with a projector for that, but you could try it). It gives you access to more colors. Rec709 2.4 is the broadcast standard used for home viewing.
As long as your display is displaying true blacks, there is no difference between bt1886 and gamma 2.4. I usually use bt1886 anyway because it is the standard for rec709 (with a 5-nit surround). For DCI-P3, the standard is gamma 2.6 for a cinema environment (0-nit surround).
As far as displaycal’s verification, I’m pretty sure you just have something set wrong (very easy to do). An incorrect CCSS shouldn’t throw it that far off, usually. A monitor like yours should have come with a correction. Use the Asus software. It has access to the hardware LUT’s on your monitor and Displaycal doesn’t. Report back with an Asus verification report. You are correct that every step will require the same correction
