I've been trying to watch HDR content on my computer and I kept running into the washout grey and bland color palette problem that a lot of people have with VLC or MPC-HC. Sometimes it would be blown out as in the example I posted below. After some digging I found two solutions that has mix results. Try each alone and than togther and see what looks the best.
1: Change the color range in the control panel to Full 0-255 instead of the default 16-235 (Limited). For NVIDIA it can be found under "Adjust Video Settings" Inside the NVIDIA control panel. AMD has it somewhere similar to this.
2: Download install MadVR plug-in. Tell your video player to use it as a default render.
Hope this helps people because it annoyed me for months now. I had it kinda working with VLC 2.5 without MadVR, but playback was laggy for HEVC 4K.