Another updated/extended version.

Download: https://adp.spdns.org/#BackgroundHDR

Added: Brightness/contrast. Added: Hide Scene objects. Bugfixes.

Cycles Brightness/Contrast shader is used instead of HSV. You have to play with the numbers for this shader. Attention: If you reduce the brightness, you may want to reduce the contrast as well. I didn't find a fitting formular to automate this. Maybe someone has an idea?

Hide/Show scene object can be used to get faster previews while working with the background. All objects in the scene are switched invisible. Before that the visible/invisible state of each object is saved and later restored.

Light On/Off shwitches all lights except IBL.

The script won't ask for a background image anymore. You have to set it by yourself (because it didn't work for me).

---