Mac’s Preview has a handy way to compress PDF files by default, by going into File / Export and select the “Reduce file size” Quartz filter
Problem is it over-compress images and make them ugly
There’s no way for you to adjust the quality in Preview, even the Utility made for it (ColorSync) can’t edit the setting (it’s grayed out). What did the Mac designers think?
You’ll have to create a filter manually to edit it.
- Download this file -> Reduce File Size
- Extract the contents
- Put it in ~/Library/Filters
You can now edit “ImageScaleFactor” key in the file to adjust the image quality (Alternatively, use the Color Sync utility)
Congratulations, you can now use Export PDF to compress them without degrading their quality