If you only want to recover a specific image from a specific slide,
simply right-click the image and choose Save as Picture from the
contextual menu.
If you want to recover all the images contained in a presentation at
once, and if your presentation file is in Office Open XML file format
(.pttx), you can also do the following: make a copy of the file and
change the extension from .pptx to .zip. If you now double-click the
file, the file will be expanded, and you should see a folder with the
same name as your presentation. Double-click it, then navigate to
ppt>media, which contains all the picture files in their original size
and resolution.
