Pitch-correction software, on a piano?

[Bob]

I've seen the software that will correct a vocalist pitch.  I was just wondering if it had been used on a piano.  Maybe an out-of-tune piano?  Or... take a historic recording and tweak notes into perfect intonation?

[richard black]

Pitch-correction software won't work on a piano because the tuning problems are invariably with unisons (apart from the bottom 10 or so monochord notes) - there are 2 or 3 strings and they are very slightly out of tune with each other.

There is a way of correcting out-of-tune unisons on a recording of a piano - I invented it and I'm pretty sure no one else has done it. It's extremely labour-intensive (I can't see a way of automating it) and it relies on knowing quite a lot about acoustics, psychoacoustics, and digital audio editing software! But I've used it on a few isolated 'twangy' notes on particularly valuable recordings.