"Use 203 Nits reference for Rec.2100 HDR" in Resolve v17.4.2

Has anyone else noticed unexpected behavior by the "Use 203 Nits reference for Rec.2100 HDR" option in Resolve Color Management in Resolve v17.4.2?

I'm getting unexpected results. According to the Resolve manual, what that option should do is automatically set the peak highlight of correctly tagged SDR input clips to 203 nits. But instead what it appears to be doing is like a gamma operation that moves 100nits to 203 nits on every clip in the timeline regardless of the input color space of the clips. It is even doing it to raw source media. Is anyone else seeing the same issue? Is this a bug, or have I completely misunderstood what's written in the manual?

CleanShot 2021-12-20 at 14.21.25@2x.png (248.08 KiB) Viewed 3540 times

From what I read it does exactly what it's supposed to do.
"Whenever you set the Output to an HDR standard while the Timeline is set to an SDR standard..."
So if your intention is to upscale your entire SDR project to HDR you would use this and thus everything gets scaled from 100 to 203. I don't see a reason why you wouldn't want all the material being scaled if that's the case. I'm not familiar with the setting but I assume it's applied between the timeline and output color space so it doesn't matter what the incoming media is. You've made everything SDR already by having the timeline be SDR. This is probably the reason it only appears when doing that.

Except the option appears even when the timeline and input color spaces are set to log OETFs such as ARRI LogC or Davinci Intermediate. That just seems wrong if the intent of the option is to simply remap the peak highlights of SDR sources.

Jamie,
I'm having trouble understanding the purpose of that option as well. Either in SDR or HDR it seems to just apply an offset no mater the other settings. It would be nice if someone who understands the programing behind this could enlighten.

I like to put titles and such at around 200 nit. And will even let some bright diffuse reflections go that high. I will even sometimes gain up to give some extra room at black for detail. But to just arbitrarily offset everything up does not seem (to me anyways) to give any advantage (unless I would then log-lift the darks back lower.)

It seems to me that the intent of this option was to just make everything brighter, which in my opinion is not a productive way to fully utilize HDR. I just leave it unchecked.

It seems to me that the intent of this option was to just make everything brighter, which in my opinion is not a productive way to fully utilize HDR. I just leave it unchecked.

that is... an opinion..... Other artists beg to differ.