There is a little command-line program that calculates optimal DPI settings for a given screen resolution and display size. I took the algorithm from a python source on an Arch Linux forum and used it in a BaCon program, The binary and source are included in the attached archive. I don't really know how accurate the algorithm is, but you can check the source code for that.
To use it, unpack and copy the binary to an executable directory.
Run it as follows:
This will yield:BaCon DPI Calculator - v. 0.1
Usage: dpicalc hres vres size
Where:
hres = horizontal resolution in pixels
vres = vertical resolution in pixels
size = diag. size of screen in inches
Example: dpicalc 1280 1024 19
Please let me know whether it works for you.Calculated DPI for screen resolution of 1280x1024 pixels and 19 in. diagonal = 86
With kind regards,
vovchik