ASUS ProArt PA32UCX monitor - LUTs etc.

My, my; it's been eighteen months since I paid any attention to this blog. Possibly the longest quiet period since I started writing it in 2003! Anyway - it's mostly down to work (I started Media Engineers at the start of 2020; a few weeks before the pandemic started).

Back in 2019 I was approached by ASUS to point a probe at their new PA32U (the first of their 32" monitors to carry the ProArt product name). It had a lot of issues and I wrote up my findings here. I also made a video showing my LightSpace profiling. 

In fairness ASUS issued a firmware update that took in my recommendations about DolbyVision and HLG. Also, in fairness they made their API available to the guys at LightIllusion which is just the thing - monitor manufacturers (almost) universally seem unable to make decent calibration software. 

SO, spin forward to the autumn on 2021 and an old pal sent me his new ProArt PA32UCX monitor and asked me to set it up for two SDR profiles and two HDR profiles;

1. Rec.709 with a gamma of 2.2
2. Rec.709 with a gamma of 2.4
3. HLG - Rec.2020 colourspace with HLG 1.2
4. DolbyVision - ST.2084 curve

At this point it's worth noting that I didn't have high hopes for the monitor for the following reasons;

1. It's a single-layer IPS (LCD) display with an LED backlight,
2. It's a FALD (so zone'd backlight) - like the Apple XDR it's an effort to make an LCD have a higher dynamic range. A typical 10-bit LCD panel (like an Eizo CG319X) can achieve about 1,000:1 but with a zone'd backlight that can be in excess of 1,000,000:1 but with the downside of halation around edges and transitions. Compared to dual IPS (think Eizo CG3146 or Sony HX-310) or OLED (typ. Sony X300) it's poor-man's HDR.
3. They sell it on the strength of it having "quantum dots"(!) yet it can achieve about the same percentage of DCI-P3 colour space as a modern non-quantum LCD or OLED.  If QD actually exists then surely it should approach laser-projector like primary colours and so get close to Rec.2020 colour primaries? Non-intuitively you need monochromatic primaries to be able to get the largest colour-triangle and that's the promise of Quantum Dots - but since this panel does not have monochromatic primaries where are the quantum effects?!

So - my first thought was that rather than using the hunt & peck four-way controller I'd like to control the monitor from it's software. So, off to download ProArt Calibration 2.0 - first on my Windows 10 calibration laptop and then my other work laptop (15" MacBook Pro 2015 model) and finally my ancient workshop Windows 7 machine - none of them could communicate with the monitor.

I tried several different USB-C cables and eventually I had to resort to a powered hub to get Windows to recognise the device. However, at no point could I get the ASUS software to talk to the display (across three machines, three OSes). Thankfully ColourSpace was able to address the monitor and drive the internal patch generator (more about that later!) - but, first job was to use my CR250 (spectroradiometer) to make a matching profile for my K10A photometer. The reason for this is that the spectro is ultimately accurate but very slow and not good near black whereas the tri-stim K10A is great near black, fast (typ. sub 1 sec per read) but is bedeviled by Specral Power Distribution issues (the K10A is an RGB probe). BUT, with a profile made with the CR250 on the display concerned you can impose spectro accuracy on the photometer.

So, here's the matching profile - for my K10A on this PA32UCX

So, the next job is to profile the monitor so we can make the various calibration LUTs. For a 17-point 3D LUT you need to measure around 5,000 colours (17x17x17) and so even with the fast Klein probe you're looking at two hours. So - I set ColourSpace to drive the internal test signal generator on the monitor and went to make a coffee. When I looked in an hour later I realised something was very wrong; essentially the internal TSG does not seem to generate any blue?!

So, I had to break out my FSI BoxIO which I normally use for patch generation and start again. Two hours later I had a profile and could use ColourSpace to generate LUTs that corrected the monitor to the two rec.709 USER slots.  I saved out the various profiles as Builder Colour Space files (.bcs) and along with the LUTs I made you can grab there at https://tinyurl.com/yej2cs5j

Now to the HDR settings and I discovered that you have to toggle the HDR-flag in the HDMI stream to get the monitor to switch into HDR mode which is plainly stupid for something that isn't a TV! No matter; break out the AJA Hi5-4K+ and use that to switch the monitor into both HDR modes.

Repeat the profile in ColourSpace and then generate the DolbyVision and HLG LUTs and use CS to upload them to the monitor. The results are not bad; here's a photo of the Eizo's luma scale in DolbyVision mode (so display-referred) and it shows around 650 Cd/m2 (not the >1,000 as their website suggests) once calibrated. In RAW/uncalibrated mode it can hit more than one thousand.

Last thoughts;

1. If you put it into HDR mode, then switch the i/p to an SDR signal, disconnect/re-connect (which you have to do) it will then let you recall one of the SDR USER settings (so 1 for 2.4 gamma, 2 for 2.2 gamma) BUT it never takes the backlight back down to SDR levels - so you get rec709 with 500Cd/m2 white. You have to manually wind the "Brightness" figure back from 100 to 10
2. "Brightness" is mislabelled - it should be "Backlight" or somesuch
3. Brightness is actually called "Black Level"
4. Their software proved useless - without ColourSpace I would have been left high and dry. 
5. All this fiddling about took days (whilst I was doing other things) - I would not want to have been faced with this at a client's site. I won't be taking bookings to calibrate these monitors.

It's like a computer monitor they've hit hard with a hammer to kinda behave like a broadcast display but they haven't listened to everything the broadcast guy told them - I would not buy this monitor - for Rec.709 I'd use an Eizo CG-series and for HDR I'd use an LG or Panasonic OLED TV.