Most oversized PDFs are really oversized image collections with text wrapped around them. Answering this pdf & documents question well means looking at evidence from the source file, the properties covered below, and what the final destination actually requires.
Pages, text flow, fonts, tables, forms, accessibility tags, signatures, and macros need separate consideration. Before anything else in “How to compress a PDF without making it unreadable,” weigh this observation: Downsample scanned pages to the resolution the reader actually needs.
Three findings that guide this choice
The core distinction
Downsample scanned pages to the resolution the reader actually needs.
The practical trade-off
Subset embedded fonts instead of rasterizing text.
The verification test
Remove duplicate objects and unused metadata after checking legal retention needs.
A practical decision for this workflow
For screen reading, test images around 150–200 ppi while keeping text and vectors intact.
Use remove duplicate objects and unused metadata after checking legal retention needs. as the acceptance test on a representative source before committing an entire archive, publication, or delivery batch.
Apply this to a real document with the PDF compressor, and see which format changes actually make files smaller when compression alone is not enough.
The pdf & documents mistake to avoid here
Printing every page to a new PDF, which can flatten links, forms, tags, and searchable text.
That failure conflicts directly with the recommendation for “How to compress a PDF without making it unreadable”: For screen reading, test images around 150–200 ppi while keeping text and vectors intact.
To see which pictures inflate a file, pull the embedded images out of the PDF first; the same reasoning as choosing a JPEG quality level then applies to each one.
Review checklist before delivery
- ✓Page count, order, dimensions, and orientation are correct.
- ✓Text remains searchable or editable where required.
- ✓Tables, fonts, links, forms, and reading order were inspected.
- ✓Signatures and permissions are revalidated after conversion.
The real bar for “How to compress a PDF without making it unreadable” is passing these topic-specific checks - a file that simply opens is not enough.