Field guide / PDF text
PDF text extraction or OCR?
Identify whether a PDF already has selectable text, understand when OCR is required, and extract a private TXT copy without uploading the document.
Try selecting a sentence in the PDF. If the characters can be highlighted and copied, the document probably has a text layer and can be extracted directly. If each page behaves like one image, use OCR. Direct extraction is faster and usually more accurate; OCR estimates characters from pixels and must be reviewed.
Text extraction compared with OCR
A PDF page can contain text, images or both
A PDF exported from Word, InDesign or a browser commonly stores characters along with fonts and their positions. A scanner commonly creates a page-sized image instead. Some scanning software adds an invisible OCR text layer behind the image, making the document searchable even though the visible page still looks scanned.
Open the document and try to select individual words. Search for a distinctive phrase. If selection and search work, direct extraction is the appropriate first method. If only a rectangular image can be selected, the file probably needs OCR.
Why extracted text can lose columns and tables
PDF describes where objects appear on a page; it is not necessarily a stream of paragraphs like an EPUB or Word file. Two-column articles, sidebars, headers, footers and table cells can therefore be returned in an unexpected order. Font encoding can also produce missing characters when the PDF does not map glyphs cleanly to Unicode.
Use extracted TXT as a working copy, not automatic proof that meaning was preserved. Compare headings, numbers, dates and table values with the source, especially when the text will support legal, financial or technical decisions.
Use OCR only when the pixels are the source
Optical character recognition analyzes the shapes in a page image and predicts characters and words. Results depend on scan resolution, language, typeface, skew, contrast, handwriting and page damage. OCR can make an archive searchable, but confidence is not the same as correctness.
For stronger OCR, begin with a straight, evenly lit scan around 300 PPI, select the correct document language and proofread names, decimal points, punctuation and similar characters such as O and 0. Retain the page image so uncertain passages can be checked later.
A private direct-extraction workflow
Choose the PDF in File Preflight and let the browser read each page's existing text layer. Review the on-screen preview, correct obvious reading-order problems if appropriate, and download the UTF-8 TXT result. The selected PDF and extracted text remain in the browser tab until you close or replace them.
- Confirm that you are authorized to reuse the document text.
- Search the output for missing or replacement characters.
- Check page transitions, columns and repeated headers.
- Use an OCR workflow separately when no selectable text is found.
Put the method to work