4K HDR video streaming named Ultra has been launched by Sony. The service will currently be available exclusively for its own 4K Ultra HD TVs. Content will be available from Sony Pictures. Apart from 4K resolution, high dynamic range (HDR) will offer greater difference between dark and light details.
Considering that there is not much HDR VOD content or devices that can play HDR, and also the service is expensive (a movie can cost as much as $30), there is a long way to go before this becomes widely adopted.