Why EDID is not trustworthy for DPI

Benny Amorsen benny+usenet at amorsen.dk
Wed Oct 5 21:11:38 UTC 2011

Matthew Garrett <mjg59 at srcf.ucam.org> writes:

> We have no technological solution for dealing with the fact that 
> applications may move from one DPI to another at runtime, and may even 
> be displaying on both displays at once.

>From a technology viewpoint, that is actually theoretically easy to
handle on modern hardware: Render everything as 3D objects and let the
graphics hardware scale as appropriate.

To get it to look pretty you would need fairly high DPI monitors or
fancy scaling algorithms though. I can imagine that sub-pixel rendering
would be quite tricky to get right when DPI changes halfway through a


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