EpubCCHow do I know if my PDF is scanned?
Updated:
Open the PDF and try to select a sentence or search for a word that you can see on the page: if nothing gets selected or found, the page is an image and the PDF is scanned. If you can select the text but it pastes as gibberish, the PDF has a damaged or poor OCR text layer.
Four quick checks
- Select text: drag across a line in any PDF viewer. A scanned page selects as one block, or nothing.
- Search: look for a word you can see. No match on a scanned page without OCR.
- Zoom in a lot: real text stays sharp at any zoom; a scan turns blurry or shows pixels and paper texture.
- Copy and paste a paragraph into a text editor: clean text means a usable text layer; missing spaces, wrong letters or symbols mean a weak OCR layer or fonts without a Unicode map.
Mixed PDFs
Some PDFs mix both: a digital body with a few scanned pages (signatures, old figures, inserted appendices), or a scanned book with an invisible OCR layer added by the library that digitised it. Check a few pages from different parts of the file, not only the first.
Why it matters for converting to EPUB
A reflowable EPUB is made from text. A scanned page has none until OCR recognises it, and the EPUB inherits every OCR mistake. EpubCC converts PDFs that already have selectable text; it does not offer OCR yet. When it finds scanned pages, the quality report of your free sample says so instead of hiding them, so you know before paying.
Evidence from the benchmark
| Engine | 8-gram recall |
|---|---|
| EpubCC engine (EPUB output) | 0.767 |
| EpubCC engine (plain text) | 0.765 |
| pdf_oxide · extract_text | 0.726 |
| pdf_oxide · to_plain_text (XY-cut) | 0.658 |
| pdf_oxide · Markdown | 0.653 |
| PDFium · text().all() | 0.746 |
| OpenDataLoader PDF (local mode) | 0.749 |
| pdftotext (Poppler) | 0.743 |
| Document | EpubCC engine (EPUB output) | EpubCC engine (plain text) | pdf_oxide · extract_text | pdf_oxide · to_plain_text (XY-cut) | pdf_oxide · Markdown | PDFium · text().all() | OpenDataLoader PDF (local mode) | pdftotext (Poppler) |
|---|---|---|---|---|---|---|---|---|
| Alice's Adventures in Wonderland, 1867 printing (scan, Internet Archive) | 0.513 | 0.494 | 0.632 | 0.639 | 0.524 | 0.651 | 0.625 | 0.156 |
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