I was bored and opened the module.ini file in the Napoleonic Wars folder. I always wondered why I couldn't choose High settings at the HDR setting in options whilst you can activate this in Native and other Warband mods.
For those who want to play on the highest settings possible and enable this feature just scroll all the way down or use CTRL+F to search for "disable_high_hdr".
You will see this line: disable_high_hdr = 1. Just change the 1 into a 0 and you're good to go.
I guess this is perfect for those who also might have a 4K monitor.
