While not really general image scaling, there's a lot of work being done on post-processing in emulators to try to emulate CRT displays (like the aperture grille) or even the quirks of NTSC.
Heh, it mentions that noone can emulate yet shadow mask CRT.
Those are what I mention in my article (TVs that have triangle pixels composed of 3 circles)
I never use current CRTs emulation because I guess I never saw TVs that could be emulated, I think all CRT TVs I saw consoles running were of shadow mask type, having almost no scanline (and I was a curious child that used to put amplifying lenses in front of TVs to see their pixels...)
http://emulation-general.wikia.com/wiki/Shaders_and_Filters