feh is a fast, yet powerful command line image viewer. It’s a swiss-army-knife for images, and fits perfectly for setting wallpaper in openbox window manager. You can choose it to set wallpaper in openbox, instead of those GUI-based tools and get the job done with ease.
To set a wallpaper using feh, open the terminal emulator and execute the command in the following format:
feh --bg-scale /path/to/the/image/file
Wallpaper can be set in any scaling options: tile, center, fill, max or scale. Replace scale in the above command with any scaling option you like.
Mention the path of the image file replacing /path/to/the/image/file in the above command.
Once you’ve set wallpaper using feh, it creates a .fehbg file in your home directory. The path is understandably ~/.fehbg.
To have the wallpaper there that you’ve set using feh every time you login, or when you begin a new session, add the following line in your ~/.config/openbox/autostart script:
sh ~/.fehbg &
This would make your wallpaper appear evey time you start a new session.