This app will allow you to turn any iOS device into a Digital photo viewer. Simply select any of your photo albums and the app will display every photo in that album for a given period of time, selecting a different random photo each time.

 Picture in a Frame has an option to only show photos that match the device's orientation. So, if your iPad is in portrait mode, only portrait photos will be displayed and the same applies for landscape orientation. 

There is also an option to dim your screen for any given period of time. This is useful to save power during the night when nobody is around to see the pictures.

As you add more pictures to your album, they will automatically appear in the app.