I've messed around with it a bit more now and I think I can explain the issue in more detail. (I am using the monitor as a second display, aka, not mirroring) In the display settings for the second monitor there is a list of resolutions. The highest specific resolution I can choose is 16xx by 10xx and then I have to check the overscan box to make it fill the screen. This distorts the image more then I'd like. The best image I've gotten so far is using the 1080p resolution and overscaning it. This should be 1920 x 1080 but when I use an image of that resolution as a desktop background it blows it up too big cutting off the edges. When I don't overscan, the image and the usable screen is smaller then the actual screen.
Does this mean the LG M2452 doesn't have 1:1 pixel mapping for 1920 x 1080?
Also, thanks for your reply, Steve.