Originally Posted by Dominic Chan
I thought THX also uses the filter. Why is HDR so much dimmer than THX? What does Natural give you?
You can also check the High Bright Color Temp. The green will be very high, but you should be able to get close to what red or blue gives you (whichever is lower), when calibrated to D65.
The brightness is more commonly measured using 10% windowed patterns, although it does not make that big a difference.
Thanks very much to all for your feedback!
I have re-run the measurements, with exactly the same sensor setup but this time I used Calman. For source I simply displayed a pure full-white image from the Apple TV. I left the Apple TV in 4k SDR output mode (High RGB). I then used Natural mode per Dominic's suggestion above, first with Std and then with BT2020 colour profile. This time I got the following measurements that finally
NATURAL / STANDARD / LOW LAMP: 23.0 fL (78.9 nits)
NATURAL / STANDARD / HIGH LAMP: 31.7 fL (108.5 nits) (!!!)
NATURAL / BT2020 / LOW LAMP: 19.5 fL (66.6 nits)
NATURAL / BT2020 / HIGH LAMP: 28.7 fL (98.3 nits)
I cannot explain why my readings were so low before using the exact same setup. The only difference is I used THX mode and HDR mode as opposed to NATURAL mode suggested by Dominic. I will try to repeat my previous measurements to understand what happened. I'm sorry if I wasted anyone's time.
I would still like to understand if I need to do anything special for HDR, like loading custom gamma curve(s), or do I just simply run JVC autocal. I have the i1 Pro2 for color calibration once I am done with gamma.