Improve HDR tonemapping brightness

[clsid2]

A common problem with current tonemapping is that the result is too dark on some monitors.

A solution would be to make DISPLAY_LUMINANCE_PEAK an input parameter in fixconvert_pq_to_sdr.hlsl. You can use SetPixelShaderConstantF to pass such parameter value to the shader. The display luminance can then be an option in the GUI. I would suggest naming it "target nits" like in Madvr. With value range between 50 and 200.

Maybe also make SRC_LUMINANCE_PEAK an input parameter. Default to 10000 like it is now. But perhaps use MaxCLL from HDR metadata instead when known?

Please don't close. I can do it in future if needed. But you can do it faster, as it shouldn't be difficult.

[Aleksoid1978]

I'm talking about the result, about the picture.