PDF compression guides

Text PDF vs Scanned PDF

Choose a workflow based on the dominant page representation.

By PDFStay Editorial Team

Last updated

A text PDF stores characters and drawing instructions, while a scanned PDF usually stores page images and may also include an OCR text layer. Text PDFs are often smaller and remain searchable at any zoom; scans depend more heavily on image resolution and compression. Identify the document type before optimizing it, because image-focused settings can help scans but may be unnecessary for born-digital text.

How can you tell whether a PDF is text-based or scanned?

Try selecting and searching for a visible phrase, then inspect the page at high zoom. Searchable text does not prove the page is born digital because OCR can place an invisible text layer over a scanned image.1, 2, 3

Decision guide for text pdf vs scanned pdf
SituationPractical actionWhat to verify
Born-digital textPreserve fonts, links, and vectorsSearch and copy representative text1
Scan or photo pagesEvaluate image-focused compressionInspect small print and OCR2

How should you verify the final PDF?

  1. Keep the original file unchanged and work from a clearly named copy.
  2. Test selection, search, page images, and file size on several representative pages rather than only page one.1
  3. Open the exact downloaded file in a second viewer before sending or uploading it.
  4. Save the destination receipt or delivery evidence when the document matters.

FAQ

Does searchable text prove that a PDF is born digital?

No. OCR can place a searchable text layer over scanned page images, so inspect selection behavior and the underlying page representation.

Which PDF type usually benefits more from image compression?

Scanned or photo-based PDFs often have more image data to reduce, but the acceptable result depends on the smallest meaningful detail.

Sources

  1. U.S. National Archives — Scanned Images of Textual Recordsgovernment technical guidanceSource reviewed:
  2. Adobe Acrobat — PDF Optimizer settingsofficial technical documentationSource reviewed:
  3. PDFStay — Compress PDF workflowPDFStay first-party methodologySource reviewed: