TL; DR
MicroSoft PowerPoint provides the feature that compress all the images in the file at once.
What happened?
In these days, the size limit of email attachment is quite tight.
Recently, I had to combine a few PowerPoint slides and send them to multiple receivers. I didn’t notice the size while I was editing the file. But when I tried to attach it into the email, the mail server refused. Only with 70 slides, it is over 30MB although they were mostly text based.
Find the Culprit
Well, you might guess already the size of the images were the problem. But I wasn’t very sure, and looked it up.
Apaprently, pptx file format is just a zip file.
If you change the file extension, you can check individual files inside
of the file.
And yes, the images were problem. Most of the pages, themes, master slides were only a few kilobytes. But some images were a few megabytes.
How to Solve?
- select a image in the slides
- navigate to Picture Format tab
- on the tab, in the Adjust group, select Compress Pictures
- under Compress Options,
- uncheck Apply only to this picture to apply to all the images
- check Delete cropped areas of pictures
- select Use default resolution under Resolution
- ta-da! 🎉