How to automate adding black pillars to create 16:9 aspect ratio images?

[Sosnovka Skydiver]

Thank you very much! I had actually looked at this program but could not figure out how to use the commands.
I think I understand the command example you included, but how do I actually use it? You said it can be done with a .bat ...?
Is it possible to run a batch, like all images in a given directory?