Houdini – Show background image in Redshift render view

To see a plate or background image in the render with a domelight, you will need to follow the following steps.

RS Light Dome

In the node RS Light Dome:

1. go to the tab Light
2. In the section General, check the Enable Background
3. Scroll down the tab until you see the Back-Plate section
4. Click on Enabled
5. Select you image in the field named Map
6. Go to Gamma Override and Click on Enable

Resources

johncccc gave me a clue on that thread.