Recently while using Windows Pro 10, I notice that my XPS 9370 adapts its screen brightness according to contents displayed on it. When I view websites with bright color theme, XPS 9370 screen will display the website's content with its maximum brightness. However, when I view websites using dark color theme, my dell laptop screen will automatically lower its brightness accordingly.
This adaptation is good because lowering display brightness helps reduce power consumption, as well as make our eyes comfortable. However, my Dell laptop often reacts too much to minor changes of contents' brightness. A huge recognizable brightness often happens even when there are minor changes to color themes. The problem turns worse when brightness incurs latency. I switch between windows of multiple applications often enough to find the brightness adaption and its latency annoying. I decided to turn off this feature.
It turns out to be quite difficult to find a place to turn off this feature. At first, I thought it was a Windows feature, so naturally I went to Windows display settings to look for it. But to my surprises, there are no corresponding option to adjust / change "automatically brightness adaption". A quick look at power settings failed to find out corresponding option. Somebody on the internet suggests looking at Intel Graphics Settings. I checked it out but find nothing there. I desperately thought that it was a hardware defect and I cannot do anything with it.
Luckily, I was wrong this time. A google for "Dell XPS 9370 brightness" leaded me to Dell Support. Someone was annoyed like me and bothered to open a dell support ticket. It seems that dynamic brightness control is a feature and it can be turn off in BIOS settings. I immediately restarted my computer, [F2] to go to BIOS settings, went to Power, and disabled this feature. Annoying display brightness adaption disappeared.
It's intriguing to find out that this feature only manifests in Windows Pro. My dual boot Ubuntu 19.04 shows no problem. This proves that sometimes a lag in hardware supports of OS is good for end users :-)