A calibrator sharing his experience matching a DIT’s LG client monitor with his Flanders XMP310 writes, “One of the trickiest parts? The ABL (automatic brightness limiting) on these two monitors kicks in at very different points, forcing us to rethink how to treat the LG TV.”
He observed that the FSI XMP310 began to limit brightness much sooner than the LG G3 and could only think of a couple of options for dealing with this, one of which was to “accept that there is a difference in when the ABL kicks in, learn to know where it is, and how to explain it to clients in the room.” That must be awkward! He adds that “the SDR is a near-perfect match. The HDR is a really good match until the ABL kicks in, and when you start moving outside of P3 (which you shouldn’t anyway). All in all, both [the DIT] and I were very happy with the calibration results, just a bit confused what we were looking at in really high brightness scenes.”
For those in a similar situation, we’d suggest option #3 instead: avoid exceeding ~200 cd/m2 FSW, or whatever the power budget of the FSI XMP310 is. All but flagship OLED TVs of the past couple of years will dim down when sustained 100% window exceeds 200 nits or so, degrading image quality. Not only that, but in the studies we’re familiar with, luminance levels of static content exceeding 25% of display peak brightness are likely to cause discomfort in viewers.
HDR video content typically has a low APL (<20%). In a study of 41 Warner Bros. titles (over 7 million total frames analyzed, corresponding to approximately 83 hr of content) in the HDR Home format that were mastered on a Dolby Pulsar display (0.005 cd/m2 black level and a peak luminance of 4000 cd/m2), MaxFALL (maximum frame average light level) of 98.6% of the frames was below 170 cd/m2 (the display power budget of the BVM-X300).
Lastly, there’s this from the ITU: “Care should be taken for any content that is allowed to go outside the reference monitor colour gamut or dynamic range as that would not have been accurately presented to the operator and cannot be trusted as part of the approved or intended appearance.” In other words, if you’re exceeding the power budget of the display, the image on the screen is no longer reliable.
The Daejeon Chronicles 
The ABL (automatic brightness limiting) can be disable in all LG models since version C9, if not previously. It’s necessary to entere the Factory Menu using the remote control pass code for the specific model.
Be aware that the LG warranty get lost by using this method. I use the C9 since 2019 as a client display. I disabled that feature and never have to deal with the Auto ABL interfering with the grading.
However, I don’t watch TV station news, sport, etc., like many home users do. Using the TV for those programs will burn the screen due to the permanent lower-third tittles ads appearing on those channel.
You can disable ASBL/TPC in the service menu. ABL cannot be disabled. “There is no way to disable ABL at all, even using a service menu of an OLED screen – it’s an inherent technical and power limitation. Nothing you can change in any service menu would turn this off.” Simon Baker, TFTCentral
https://tftcentral.co.uk/articles/oled-dimming-confusion-apl-abl-asbl-tpc-and-gsr-explained
Thank you for the clarification.
Sure thing!