Recently during my Lubuntu 12.10 Quantal Quetzal review I've noticed that after installing proprietary Nvidia driver my fonts were a little too small. Since I've discovered the problem was in fonts DPI value, in this article I'll show you how to specify your fonts DPI manually inside your xorg.conf.
Proprietary Nvidia drivers are smart enough to access your monitor EDID to detect it's panel DPI settings. Unfortunately that DPI makes my fonts too small because I like my fonts at standard 96 DPI. Most desktop environments come with GUI tool where you can specify your font size and DPI. LXDE from Lubuntu unfortunately doesn't have this tool so you must specify your fonts DPI manually inside your xorg.conf.
I'll assume you have your proprietary Nvidia driver installed. First thing you must do is to generate default xorg.conf like this:
sudo nvidia-xconfig --no-use-edid-dpi
This will generate default xorg.conf and disable use of DPI info acquired from your monitor EDID. Now you are free to specify your desired DPI by placing following inside section "Monitor" of your /etc/X11/xorg.conf:
Option "DPI" "96 x 96"
You can change DPI value from 96 to your desired value. Changes should be noticeable after reboot.