Check to see if your xbox is set to "auto detect" for your screen resolution setting?
If so, try and switch to manual setting and choose the higher resolution supported by BF4 and your screen.
This is btw one of the most common issues when utilizing its full 120hz refresh rate and the 4K resolution features. The symptoms can be anything from corrupted images to nothing popping up on the screen.
Update your TV/Monitor
In many cases, it is not the Xbox that is causing the issue. It is the TV, and Microsoft has found that various TVs from brands like Samsung and LG often present this issue. For that reason, if you are running a smart TV, make sure it is updated to the latest firmware, especially if it is an LG, Samsung or Vizio TV. This should fix the issue, meaning that you will be able to run the 4k/120hz feature.
Note that another problem can also be caused by VRR (variable refresh rate) settings on a TV !
Follow the instructions provided by the TV guide to disable this or enable VRR and see if the image quality has improved.
Turn off VRR on the console
VRR stands for variable refresh rate and works by allowing the TV to adjust its refresh rate real-time to the output of the game's frame rate. Unfortunately, this can cause problems with certain TVs, giving you corrupted images and the game will default then by swithing to lower resolutions. As such, a quick fix if you are running 4k/240hz with VRR on is to disable VRR.
If you do not know how to disable or enable VRR, go to "Settings", then "General." In there, you will find the "TV & display options" option. Click on it and go to "Video Modes." Here, look for the option that says, "Allow variable refresh rate." Enable or disable it as you see fit, and test to see if the image has improved. You can also change the refresh rates and resolution in "Display." Mess around with these settings to see which one works best, and make sure the resolution matches the one your TV can handle. Once you have set the options, restart the console.
Perform a reset
If none of the above solutions has worked so far, you will need to do a video mode reset sequence to get everything back to its default settings. In other words, you are going to revert your Xbox's display settings to the original.
To do this, hold the power button on the console for five seconds. Do not release it until the console powers off. With that done, press and hold the Xbox button again along with the eject button (note that there should not be a disk inside). Hold it there until you hear two beeps. The console will then boot your console in low resolution, in which you can navigate back to the display settings and choose the appropriate resolution.
Best of luck with it !
