I have an Intel HD 4400, which is in Optimus with an Nvidia 750M, this is on a Dell laptop, with Dell custom graphics software it is out of date and present the same fault.
When I view a screen with white it shows the normal gamma, contrast, brightness, etc, when I view a screen with black, the display tries to gradually step the contrast higher which causes viewing issues and eyestrain, it's also very poor for image reproduction.
The drivers I have tried are:
I'm using Windows 10 64 bit, all drivers, and firmware are the latest except for Intel IMEI, which is at version 9.5 because there is a bug with sleep/hibernation/power off where it hangs while being unusable. I posted elsewhere on the forum about that.
Here is an image of the setting turned off in Intel HD graphics control panel > power > Display power saving technology, despite this setting it still changes the contrast dynamically.
The problem occurs when the device is plugged in and set on high performance, balanced, or power saver, I have also disabled the built in display saving in Windows power options.
If I unplug the a/c adaptor, then replug it, the dynamic contrast does not occur for some time, there is clearly a problem with the software causing this setting to be occurring even though it's turned off.