PDF fundamentals
How PDF compression actually works
Two PDFs with the same number of pages can differ 100× in size. The reason is almost always images. Knowing what is heavy tells you exactly how to slim a file down.
Text is nearly free
Text is stored as compact drawing instructions plus a subset of the font. A 50-page text report is often under a megabyte. Text is rarely the problem.
Images are the weight
Scanned pages and photos are stored as compressed images (usually JPEG). A single high-resolution scan can be larger than a whole book of text. Re-compressing images is where real savings come from.
How to shrink a PDF
- Re-encode images at a sensible quality and resolution.
- Remove duplicate or unused resources.
- Avoid embedding full fonts when a subset will do.
In FreshPDF
The compress tool re-encodes each page as an efficient JPEG on your device — great for scanned documents that are too big to email.
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