Guide

How to make a scanned PDF searchable

Open OCR PDF, add the scan, choose the language of the document and press Make searchable. PlumPDF reads each page and adds the words as invisible text, so you can search, select and copy. The recognition runs on your device and the file is not uploaded.

By Akash Gupta · · Updated

Open OCR PDF

Step by step

  1. Open OCR PDF. Go to the OCR PDF page on PlumPDF. No account and nothing to install.
  2. Add your scanned PDF. Drop the file on the box. Each PDF can have up to 50 pages, and you can add up to 50 files.
  3. Choose the language. Pick the language the document is written in. Ten are available, from English and Hindi to Arabic and simplified Chinese.
  4. Make it searchable and download. Press Make searchable, then download the searchable PDF, the plain .txt file, or both.

Why can a scanned PDF not be searched?

A scanned PDF is a stack of photographs of pages. To a computer there are no words in it, only pixels, so search finds nothing and you cannot select or copy a sentence. OCR, short for optical character recognition, reads the pictures and works out which letters and words they show.

What do I get back?

You get two files. The searchable PDF looks exactly like your scan, with the recognised words laid invisibly over the originals, so search and copy work. The .txt file holds the same text in reading order, with a line between pages. Columns and tables are not kept as a layout in the text file.

How do I get a good result?

Clean, straight scans of printed text work best. Accuracy drops with blurry phone photos, skewed or curved pages, unusual fonts and very small print. Choose the right language, and if a document also contains English words, tick the box to read both at once.

Check names, amounts and dates in the result before relying on them. Handwriting is not read reliably.

What are the limits of searchable PDFs?

Recognition is heavy work for a browser: expect a few seconds per page on a laptop and longer on a phone. A PDF over 50 pages should be cut first with Split PDF. Pages that already contain real text are left alone, and their text goes into the .txt file.

The first time you use a language, your browser downloads the recognition engine and language data from PlumPDF and keeps them for next time. Your document is not sent anywhere.

Questions

Will the pages look different afterwards?

No. The scan keeps its full quality and the file grows only a little, because the text is added as an invisible layer.

Can I stop it part way?

Yes. A progress bar shows which page is being read, and Cancel stops straight away.

Why did my search still miss a word?

Recognition is not perfect, especially on poor scans. The word may have been read slightly wrong, so try a shorter part of it.

Does it work offline?

Once the engine and language data have been downloaded and kept by your browser, the reading itself happens on your device.

Which languages can it read?

English, Hindi, Bengali, Marathi, Tamil, Telugu, Gujarati, Spanish, French, German, Portuguese, Indonesian, Italian, Arabic and simplified Chinese. Pick the one the document is mainly written in. Each language is a separate download of 1 to 3 MB the first time you use it, kept by your browser afterwards.

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