DPI in a dual head setting

Éric Piel E.A.B.Piel at tudelft.nl
Wed May 18 08:44:55 PDT 2011

Op 18-05-11 16:13, Raghavendra D Prabhu schreef:
> Hi, I have a laptop (15 inch) and an external monitor(23 inch) in a dual
> head setting, both supporting maximum resolution of 1920 x 1080. Now
> the DPI calculated by Xorg from EDID/DisplaySize is found to be 143
> x 143. The problem with that DPI is when I shift windows ( like
> terminal ) from external one to the laptop one, the fonts look
> really tiny. If I calculate DPI myself from size and resolution, the
> DPI for one comes to 120 and for another 143. So is there a way to
> assign different DPI to each of the physical screens ? I am running
> them in a twinview mode (nvidia).
I beleive it's not possible to have different DPI's because the X server 
is not enough vector-based: it wouldn't know how to zoom/unzoom the 
windows when moved from one screen to another.

One possibility however is to "zoom" your laptop screen so that things 
in it appear physically as big as in the external monitor (but you loose 
the point of having a high DPI and font anti-aliasing fails).

With xrandr 1.3, you can do it with:
xrandr --output LVDS1 --scale 0.65x0.65

Or unzoom your external monitor:
xrandr --output VGA1 --scale 1.2x1.2

However, I don't know if nvidia/twinview supports it.


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