Exposure and Gamma Controls for Real HDR

As amazing as HDR can be, the worst part is the variance in controls different games give users. Most games target moderately bright room viewing with 200-300 nit paper whites, with the equivelant SDR gamma it's mapping from being g2.2. Put on right after a nicely mastered film in a light controlled room, this is eye searing with their 100 nit paper white targets and g2.4 sources.

I would be thrilled to use a shader with PQ-space controls for exposure and contrast, that would allow for so many games to finally be playable and lovable in HDR once and for all.

To clarify with source gamma and paper whites and why this is of interest, I am referring to many games like Battlefield V: compare SDR g2.2 at 200 nits versus HDR, you can see and measure the it's the same image until super-highlights and super-saturations. Decreasing the game's HDR exposure (brightness) can get you to an equivelent of SDR 100 nits, but still at g2.2, leaving you with less contrast than a properly rich dark room image. This is likely the result of using an ACES tonemapping operation with surround compensation, but I can't be certain. Movies are measured the opposite, put on a film in SDR to 100 nits g2.4, and you will often see an extremely similar match to HDR, though of course there is more shot-by-shot adjustments colorists make that make it not as 1:1.

A moderate amount of HDR games these days give exposure controls to get the paper white where we want, but only an extreme few give contrast control. God of War is the only I've seen to do both, allowing perfect calibration to any ambient room lighting.

 

I don't have an HDR monitor myself nor worked with reshade in HDR but in general the quality of HDR is heavily dependent on developer's creative intent, their implementation in the game and the quality of the user's monitor. Even certain movies can have a massive shift in brightness for SDR vs HDR just because a director wants to "blow things up" for the HDR experience.

In the ideal world we'd have ways to compensate / track PQ depending on the monitor's capabilities and viewing environment perhaps similar to what HGIG is trying to solve for consoles.

For Battlefield V I think they did a terrible job at tone mapping SDR but luckily you can change this with console vars. I did this at the time I played it.
You may be able to do similar things in HDR.

In regards to exposure and gamma for HDR, if I'm not mistaken a game or movie's image feed is actually log(like) and the display maps that to the respective nits because the feed is 10bit and the data needs to fit in there similar to capturing camera log. In color grading world you change exposure with offset if it's on log footage which could be a very simple shader. I'm not aware of any current ones that have this operator but it's likely what you want, or at least try. Gamma is trickier for PQ perhaps but simple contrast sliders should have similar effects on HDR footage as SDR that might do the trick for your purposes.

(sorry if image below is massive, first time posting, don't know how to do it properly)