dpi
I am trying to find and then change the screen DPI (dots per inch) setting in 12.04 and 12.10. However, I can't seem to find any app or config file that can do this. Is there any app or conf file for this?
Note that this is for 12.04+ so the following will not work:
Moreover, they are basically changing the font size, not the actual screen DPI.
Configuration can be done per-user through ~/.fonts.conf, and globally with /etc/fonts/local.conf. The settings in the per-user configuration have precedence over the global configuration. Both these files use the same syntax.
Just scroll down and change the DPI value in the conf file. You may have to restart x or logout/login to KDE to get the change to apply.
This applies to most DEs, I don't know of any GUI method to do it other than what you have tried already.
This is a common issue on the forums - the move to gnome3 has dumped many of the customisation features that were available in gnome2.
One GUI tool that exists in Software Center is gnome-tweak-tool - its a partial solution to allow you to customise some aspects of fonts.
The "Text scaling factor" is the option you are interested in - its unfortunate that it is a sliding bar so you will not be able to enter the actual DPI value. Click on the sliding bar and use the left/right arrow keys to decrease/increase the font size.
Using dconf-editor which is available in the dconf-tools package allows you to set the "Text Scaling Factor" numerically i.e. changing the default value by fractions of numbers (1.2, 0.9 etc) changes the overall screen font size:
If you just want to adjust the text size universally without need detail you can do this from the universal access tool:
Best Answer
This is an updated version of my previous answer which was related to Ubuntu 12.04. In 16.04 (Xenial) 3 steps are needed to set DPI correctly instead of 2.
I'll explain on the example of the system with Ubuntu 12.04 with Gnome Classic and a monitor with resolution 1680x1050. My starting settings:
xdpyinfo | grep dotsreported96x96 dots,xrdb -query | grep dpireportedXft.dpi: 96,grep DPI /var/log/Xorg.0.logreported some weird settingsNOUVEAU(0): DPI set to (90, 88).In 16.04 the outputs of all these 3 commands were consistent and were equal to 96. Though such consensus is better than the disorder of 12.04, the reported value is hardcoded and far from the real DPI value.
Let's calculate optimal DPI for my monitor. Actual size of the screen can be found with the command
xrandr | grep -w connected(convert output to centimetres) or with a long ruler by hand. In my case:X = 47.4cm;Y = 29.6cm. Divide them by 2.54 to get the size in inches:X ~ 18.66in;Y ~ 11.65in. Lastly divide the actual dots amount (based on your resolution) by the size in inches:X = 1680/18.66 ~ 90dpi;Y = 1050/11.65 ~ 90dpi. So my real dpi is 90.Be warned, the manual method of measuring may be more accurate, than the output of the command
xrandr | grep -w connectedbecause the newer versions of X server ignore the size reported by EDID and calculate the size using the screen resolution and a hardcoded value of DPI (more info here).Another method how to find the size of the monitor is to read its EDID directly. Install
read-edidpackage and run the commandsudo get-edid | parse-edid | grep DisplaySizein the terminal. Its output will give you the actual size of your monitor in millimetres. If not - use the ruler.Let's start fixing DPI:
1) In 12.04 run
gksudo gedit, open/etc/lightdm/lightdm.confand add a parameter under[SeatDefaults]section:There's no such file in 16.04 by default, so you must create
lightdm.confmanually and put it into/etc/lightdm/lightdm.conf.d/. The contents of this file are the same:Restart your computer or restart X. Now
grep DPI /var/log/Xorg.0.logwill show the desired setting.2) In my former answer I proposed to create a file in
/etc/X11/Xsession.d/containing stringxrandr --dpi 90. This worked in 12.04, but in 16.04 this setting isn't persistent. In newer systems we can add the desired value on session start. Run "Startup Applications", press "Add" button, name it "Fix DPI" and set the commandxrandr --dpi 90in the field. Save the changes and re-login. Nowxdpyinfo | grep dotswill report90x90 dots.If
xdpyinfostill shows 96 then add a timeout before runningxrandr. Edit the command in "Startup Applications" and change it to:Reference
Step 2 is optional for 12.04 because in older systems Step 1 fixes both
Xorg.0.logandxdpyinfovalues.3) In GNOME3 DPI setting is hardcoded to 96 and cannot be changed directly, but the text can be scaled instead. Calculate the desired multiplier:
desired_DPI / 96(in my case90/96 = 0.9375). Now run the command (or usedconfif you prefer):Changes will be applied at once.
xrdb -query | grep dpiwill report the desiredXft.dpi: 90.P.S. There is another method to fix DPI setting which is much more difficult and it is described in this guide. I tried it also and the result was the same (at least in 12.04).
Afterword: Only Ubuntu developers can say for certain whether values modified by Steps 1 & 2 really matter in modern Ubuntu or they are silently ignored. Only Step 3 produces the changes which are instantly noticeable. Those users who consider that certain apps may still rely on X server settings are encouraged to perform all 3 steps described above. For the rest Step 3 is sufficient - that's the sole way of customization adopted in modern Ubuntu distros.