Sony bravia sucks for hdr, its too dark and greyd out... but go into the advanced picture settings while playing hdr, then into color, and select colour space BT.2020 instead of auto. Also be sure that in your settings you are using the 4k input for the hdmi, and for me on the ps4, I need to go into the screen settings and select An 2160p YUV420 resolution, not sure for xbob tho! Hopes it helps good luck!

the image seems ... dull...

HDR (with full range color) tends to do that. The saturation is reduced when switching between non-HDR to HDR. Probably one reason is that the TV can now display the whole range of color instead of being "crushed" (i.e. black or near-black being rounded off, etc).

I think I'm in HDMI port 3, though. At least that's the recommended one for my X75f.

Try resetting the display options to default, then adjust the values WHILE on HDR mode. If you're in non-HDR mode when you adjust, HDR would look muted when you switch to it.

Another technique is to switch to a different picture mode when in HDR. In my case, I use the Cinema Pro, and add all the bells and whistles for HDR there. Then if I'm in a non-HDR game I switch to another picture mode like Game Mode, where I turn off all post-processing stuff.

EDIT: As for smoothness in Bravia TVs, that's for frame interpolation (the Soap Opera effect). Normally you turn that off for games as it introduces some latency. But I do turn it on for certain game types, like games that do not require millisecond-level responses.

A good way is set it through the calibration on the Xbox. Set your TV one of the default presets and turn on the gaming part. It has a calibration guide in the setting there where it guides you through until it's what you want .

What do you use to try out HDR? Do not use RDR2, HDR implementation is fucked in this game. The insects demo app is a good one to try out HDR on the One X.

1. I had that issue till I updated to Oreo and did a factory reset. Now every thing is twice as bright and vivid. Do the update of it's not there yet already do factory reset
2. Don't raise contrast over 90. Over 90 on n ty xf90 (x900f) it blows up and destroys all highlight detail
3. For games set color to 60
4. Make sure to calibrate your TV with every game. / Calibrate the in game settings for hdr. Some games just have shit hdr. Or bar calibration options

PS4 exclusives have great hdr. And farcry5 had great hdr that looks like crap of is not calibrated properly

5 try looking into the sky and calibrate contrast based on the clouds,. Don't look directly at the sun. It's supposed to be a bit overblown. But look at clouds and make sure you see all details. That is isn't so bright that it all turns in to the same color of bright white

I'm using the xf90 / x900f and the quality was dog shit before the Oreo update the but that was a bug and others didn't have that issue. Try to factory reset. Check if you have the update ota or check on sony site and fieldput the update on a USB. Regardless do a factory reset. Do one if you don't have an update and do one if you do have the update

Now my hdr is incredible

HDR is hit or miss because of lacking standards. I've tested it to mixed success on my Shield TV and day1 PS4 (5 years old?). Both support HDR but maybe different standards.

HDR sometimes works sometimes doesn't which is a shame because it's way better than 4K in terms of visual enhancement.