I think you mean backlight, not brightness. I was able to get EG with HDR to look pretty good, but in order to do so I had to do the following in addition to the normal Game Mode process of cranking backlight to 20:
- Gamma to +3 (from 0)
- Dynamic Contrast to Low (from Off)
Otherwise it was just too dim. Are they really shipping these games with HDR modes that are flat-out broken or is there some kind of issue with the PS4 (Pro), the KS8000, or the combination of the two? I don't have any issues with HDR on the TV's built-in apps or with Planet Earth 4K playback on the X1S. I haven't played any HDR games on the X1S recently (saving them for the X1X) but I think the Forza Horizon 3 demo was in HDR and it worked as intended.
Does EG's HDR mode work properly on other sets (Sony, LG, etc.)? I don't know.
Dynamic contrast controls the local dimming, you cannot achieve HDR without that.
The problem with HDR10 is that it entirely down to the TV to decide how the content should look.
For content producers this means that mastering it is actually pretty difficult.
Normally you grade and tone an image from the raw footage to look the way you want it to , however with HDR10, some of this is decided by the TV and however the TV manufacturers chooses to process the image.
Here is a colour grading example of raw video footage before it is toned, it doesn't contain any more data, it is just presented differently.
The lefthand example is similar to what many people are seeing when they enable HDR.
This flaw in HDR10 as a format and is why you not only get such wildy varying results between TVs, but also between users, because their is no reference to calibrate against.
Another issue with HDR as a format for gamers , is that it inherantly requires processing to look like it should, so it will always have more lag than the pre-toned SDR game content.