I'm looking for the author of the painting & the place where I can see it (museum)
It's a portrait of Tommaso Traetta, XVIII music composer. Traetta was
named also: trajetta, traetto, traetti, traeta, traietta, traietto.
http://www.traetta.com/img/traetta01.jpg

Cippalippa,

I looked every way I could think of, G-pictures, T.T. Parma, Venice OR
Venedig OR Venezia and so on.  No luck.  Parma has a nice site where
you can steer the camera around in various areas, but no portrait.
I would bet the price of your question that the portrait is in Parma,
maybe in the Teatro Regio, but that is just based on the fact that
Traetto spent 9 years there and wrote 40 operas.  Second choice,
Venice, by then he was maybe famous enough to have his portrait hang
in the Ospedale (? your Italian is certainly better than mine). 
Somewhere I found a small picture of an interior of the place.
Was that no help?  Call someone in Parma.
Ciao
Myoarin