I want to extract a lot of useful imaging photos from a Powerpoint slide deck, and the usual way to select each photo and save them has two distinct disadvantages:

• time consuming and repetitive
• photos are not saved as the original quality

Modern Powerpoint files with the .pptx extension are actually zip archives. Rename the .pptx file into .zip file, and look into the media folder. 

If it's an older .ppt Powerpoint file, first open up the file in Powerpoint, then save as .pptx

Using Windows Explorer, browse to the location of the Powerpoint file, and rename the .pptx file to .zip

 Using Windows Explorer or a File archiver utility such as PeaZip, extract the content of the newly named .zip file

  You should now see a ppt folder, with a media subfolder containing all the photos in the slides.