PDF compression guides
How to Compress a PDF with Images
Image-heavy PDFs need a visual comparison, not just a byte-size comparison.
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For an image-heavy PDF, estimate whether the file is large because of photographs, scans, or oversized page images. Start with a moderate image-aware setting, then compare faces, text inside images, diagrams, and color transitions with the original. Download and reopen the result, because a successful process only proves a file was created—not that every important visual detail survived.
Identify which images deserve detail
A photograph in a portfolio, a scanned signature, and a screenshot of a chart do not have the same quality requirement. Resolution and visual purpose matter more than a generic percentage target. PDFStay's compression examples are measured fixtures, so use them as method evidence rather than a promise for your file.1, 2
| Image type | Priority | Check |
|---|---|---|
| Photograph or illustration | Tone and fine detail | Compare at intended viewing size |
| Scan, signature, or chart | Characters and line edges | Zoom into the smallest marks |
Compare representative pages, then the whole file
- Record the original size and select pages with different image types.
- Compress a copy with a moderate setting.
- Compare representative pages at 100% and zoom.
- Review every page before sharing the downloaded output.
FAQ
What compression mode is best for a PDF full of photos?
Start with an image-aware or moderate setting and inspect representative photographs. Use a lighter setting when the images themselves are the deliverable.
Can compression improve a blurry scan?
No. Compression can reduce bytes but cannot restore detail that was absent in the original scan.
Sources
- PDFStay — Compress PDF workflowPDFStay first-party methodologySource reviewed:
- PDFStay reproducible compression checksPDFStay first-party methodologySource reviewed: