ruler http://people.csail.mit.edu/jaffer/Gamma/sizecal.html

Image Size Calibration


Image elements in the PostScript language are sized using physical units (not pixels). If your computer can display PostScript pages, then the ruler in "grayrule.ps" should match a ruler held up to your screen.

If it doesn't and you are using XFree86-4, then add this entry to Section "Monitor" in /etc/X11/XF86Config-4:

       DisplaySize  width height
              This optional entry gives the width and height,  in
              millimetres, of the picture area of the monitor. If
              given this is used to calculate the horizontal  and
              vertical pitch (DPI) of the screen.


I am a guest and not a member of the MIT Computer Science and Artificial Intelligence Laboratory.  My actions and comments do not reflect in any way on MIT.
agj @ alum.mit.edu
Go Figure!