When I export a 5mb pptx to pdf using powerpoint for Mac I get a 30mb PDF. Using the Compress Pictures option form powerpoint doesn't make any difference
Step 1 – Compress pictures in PowerPoint
- From the File menu choose Compress Pictures, Choose Email as the picture quality and save the file.
- Check the new pptx file size, it should have reduced a little
Step 2 – Change quality preferences in PowerPoint - Click on the PowerPoint menu, between the Apple logo and File menu and choose Preferences
- Choose the General option listed under Authoring and Proofing Tools
- Select the drop down for Print Quality, set the desired quality to Low.
- Export to PDF as usual and the file size will now be much smaller.
- Open the PPT file using Keynote.
- Modify some: font size etc.
- Export as PDF with "quality of image: high".
The size of PDF converted using Keynote is mostly same with that of PPT, without downgrading the quality of images.
It is no doubt that there is a problem in the conversion process of PowerPoint for MAC.