How to compress images in all PowerPoint files in a folder

Hi,

I have a project where I am being sent a lot of slide decks and while some authors create a very compact pptx others are adding images that are top quality (300dpi) and this leads to a very large pptx which I need to open, edit, compress images and re-save.

I'd love to be able to automate this from PowerShell so I can bulk process all files in a directory but I cant see any image compression method in the PowerPoint SMO. 

Can anyone advise if its possible and what references might assist me please?