Choose PDF compression with a readable result

Different PDFs have different size drivers

A scan may contain one large image per page; a digitally generated document may contain searchable text, fonts and vector graphics. Raster-based compact output can reduce some image-heavy files but can also discard selectable text and vector detail. It can even make an already efficient document larger. Keep the original and choose a compression method based on how the result will be used.

Inspect the difficult page first

Use a page containing small text, a fine diagram and a photograph as a test. Compare the original and exported file at the size at which people will read or print it, then zoom in to inspect artifacts. Check Korean or other dense glyphs, thin lines and shaded tables. A smaller byte count is useful only if the information remains legible.

Review: smallest text → thin lines → photographs
Compare: original bytes / output bytes / readable content

Keep the right version for the next task

If the recipient needs text search, copying, accessibility tags or form fields, inspect those features after any conversion. For an archival master, retain the original and distribute a separate smaller copy where appropriate. If compression produces a larger file or unreadable text, do not replace the original. Try a less aggressive setting or a different document workflow. There is no universal compression percentage that works for all PDFs.