Does PDF Compression Work on Scanned Documents?
Yes — a scanned PDF is just embedded page images, so compression re-encodes them and cuts size a lot. The trade is some softness, because you are shrinking pictures, not text.
Why scans shrink so much
A scanned PDF stores each page as a picture. Re-encoding those pictures at a lower quality (or downsampling DPI) removes a lot of bytes — often far more than on a text PDF.
Real results
| Scanned file | Before | After (High) |
|---|---|---|
| 9 MB scanned chapter | 9 MB | ~480 KB |
| 31 MB scanned packet | 31 MB | under 9 MB |
| 40 MB scanned textbook | 40 MB | ~6 MB |
What we verified
Scans are where compression pays off most. A 40 MB scanned chapter dropped to ~6 MB and a 31 MB packet to under 9 MB in-browser, with no upload. The pages were softer but fully readable on screen.
Honest note: if you need the scan for OCR or print, keep the original. Compression trades a little sharpness for a lot of size — fine for screen sharing, not for re-scanning.
FAQ
Does compression work on scans?
Yes — scans are images, so re-encoding shrinks them a lot.
Will the scan stay readable?
At a moderate setting, yes; very aggressive settings soften photos.
How much can I save?
Often 70-90% on scan-heavy files; we saw 40 MB drop to ~6 MB.