User mkoper over at the Calman forums http://www.spectracal.com/forum/view...p=41495#p41495
has come up with a nice idea to be able to calibrate HDR on projectors, the problem being that there is no EOTF defined for projectors, so with a peak Y at 250nits at best, the charts are not useable to do any meaningful corrections.
The idea is to use the matrix (meter profile) to multiply all the values by the same multiplier in a diagonal line in the matrix (intersection of X/X, Y/Y and Z/Z), so that you can actually use the charts to make some corrections. I found that a multiplier of 4 worked best in my setup (210nits peak became 840nits).
So I used a multiplier of 4 and I was able to do a very nice correction to my Gamma D preset.
On my tiny screen which still gets 210nits with high lamp / iris full open, I ended up quite far from the JVC defaults: PT=7, DG=4 or 5, BG=2.
In this lamp/iris setting, Dark Gamma raises the black floor above 4 with a 0% pattern, 5 with content (seems higher than when I tested with low lamp iris -9). Brightness above 1 (HDMI standard).
The result is very, very nice. This doesn't help with the raised black floor or the lack of DI, but the HDR picture was better than usual with close to the JVC defaults. I only gave it a quick try as I had a limited amount of time, but it's an encouraging development for those who would like a better calibrated HDR mode.
I need to run some content, but I advise those who have some calibration gear to try it. It's easy and it's a decent workaround.
Of course you need to select BT2020 and ST2084 PQ Gamma as targets, and you need an EOTF graph (not a gamma log/log).
I don't want to hijack the thread as most people don't care about this low level calibration stuff, but I thought I'd give the info to those who do.
PS: these results are NOT translatable as they are set-up dependant. You need a meter and a software to reproduce this and adapt it to your set-up.
If you have any question, feel free to post in the Calman thread linked above if you have Calman, or in the forum/thread of your favourite software if you don't have Calman.