Always remember a TV is not a monitor. Monitors are made to respond to colour more accurately than TVs, out of the box. If you want to use a TV as a monitor then you will very likely need to change a lot of settings in the TV itself to make it behave more like an accurate monitor. I know it's annoying, hardly any TV manufacturers do this out of the box.
The first thing to remember is that the HDMI spec requires that HDMI displays respond to colour differently than non-HDMI (computer monitor) displays. The HDMI spec says that all values 0-16 are full black and all values 235-255 are full white. This is called limited RGB mode and you will need to tell BOTH the Nvidia driver and the TV to switch to full range RGB mode instead so that they render shades more accurately like a monitor. As a second preference, you should be able to tweak the gamma values in the nvidia settings utility. Your gamma exponent looks too high so reducing it will bring back those missing shades. You can also choose a colour profile in Settings > Devices > Color which may help to change the gamma curves to your liking. I hope you find a solution in one of those. Unfortunately since you're using a graphics driver that's not from the Ubuntu archive, we can't really handle bug reports about that here. If you are willing to downgrade the driver to a supported version like https://launchpad.net/ubuntu/+source/nvidia-graphics-drivers-390 then you can open a new bug report by running: ubuntu-bug nvidia-driver-390 ** Package changed: xorg (Ubuntu) => ubuntu ** Changed in: ubuntu Status: New => Invalid -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to xorg in Ubuntu. https://bugs.launchpad.net/bugs/1785764 Title: Some applications render too dark when a 4K screen is attached. Status in Ubuntu: Invalid Bug description: Using Ubuntu 18.04.1 LTS Running on an i7-6700k with a GTX 1080 Reproducible with nvidia-driver-396 or xserver-xorg-video-nouveau and a single 4K screen (TV) connected via HDMI. The issue: Any dark content displayed by an effected application (e.g. a very dark image or dark themed web page) is much darker than intended making it almost unusable. This only effects applications that are launched when the 4K screen is connected. If i disconnect the 4K screen, launch the app via a different 1080p monitor then reconnect the 4K screen the app remains unaffected. The only apps i have found so far that are effected by this are Google Chrome and Image Viewer. That said this is only noticeable when the app is displaying dark contend so if other apps are affected it may be impossible to tell. The attached screenshot uses a black to white gradient image to clearly demonstrate the issue. Is seems like it may be an issue with colour depth as bellow a certain brightness it just goes strait to black. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+bug/1785764/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
