ROME (AP).- A finely painted portrait of a demurely looking woman nestled in an exceptionally ornate frame that was kept in an Italian ducal palace storeroom appears to be a Raphael original and not a copy as long thought, an art official in central Italy said Friday. However, experts on the Renaissance giant quickly cautioned that art historians would have to closely study it before any conclusions can be made. Mario Scalini, state superintendent for art in Modena and nearby towns, said he was doing an inventory of about 20,000 paintings in storerooms after he was named to the post a few years ago when he was struck by an unusually fancy, gilded 17th century frame in the palace in Sassuolo, near Modena. It surrounded a portrait of a lady, hair braided, head tilted to one side