I have a solo show for my photography coming up and am going to have a slide show on a television going during the show. I am wondering what is the minimum resolution for the photos. It may be blown up on a wall during the opening talk. It's is in Italy and I am a little worried about someone ripping off highly printable files.
It depends on the screen and projector used. If they are both standard HD, that's 1920 x 1080 pixels.
4K screens at 3840 x 2160 are becoming more common. 4K projectors are still quite expensive and not as widespread.