Red portal

You walk through the red portal, and you find two huge paintings.
They are as big as a wall, and you are impressed.

The paintings seems to be alive, you feel that you can use them like portals.
The first is a barren land, with an eclipsed red sky, maybe is the abyss?

The second one is dark, full of dark, purple crystals, you can see a strange city far away on the horizon, maybe it's the Underdark?