CECO PDF

Five ways to change text in a scan, compared

A scanned PDF is a picture of paper, with no text to edit until something makes some. There are five ways to change a word in one: retype the page, recognise its text with OCR and edit that, convert it to Word and back, cover the word and type over it, or correct it in the picture itself.

By CECO PDF · Published · Updated · Facts about other tools checked on and

Why a scan is different

A PDF saved from a word processor holds its words as text, which a program can select, search and change. A scan holds a picture of each page instead. Its words are ink in that picture, with the grain of the paper, the blur of the scanner and the tilt of the sheet around them. To change one, a tool has to turn the picture into text first, or change the picture itself. Either way, the thing to check afterwards is what happened to everything you did not mean to change: the other lines, the signature, the stamp and the layout.

The five ways side by side

Five ways to change text in a scanned PDF

WayWhat changes on the pageGood for
Retype the pageEverything: it becomes a new documentRewriting most of the page
OCR, then edit (Acrobat Pro, Smallpdf Pro)1, 2The words are recognised and become editable text; how new text looks depends on the toolMany changes, or whole sentences
Convert to Word and back (Word, PDF24's advice)3, 4The whole page is rebuilt, and the layout may differA document you will go on editing
Cover it and type over it (Sejda's whiteout)5A white box hides the word; new text sits on topA quick fix on a page with plain white paper
Correct it in place (CECO PDF)Only the corrected words; the rest is checked unchangedA wrong word, date or number in a scan that must stay as it was

Type the page again

Retyping the page in Word or another editor and saving a new PDF needs no special tool, and gives you a clean document that you can change freely afterwards. It is the right choice when you mean to rewrite most of the page anyway. What it costs is everything that made the page a scan: a letterhead, handwriting, stamps and the layout have to be rebuilt by hand or are lost, and the result is a new document rather than a corrected copy of the old one. For a single wrong digit on a long scan it is a lot of work, and every line typed again is another chance for a new typo.

Recognise the text with OCR, then edit it

OCR reads the letters in the picture and makes text that an editor can change. Adobe says that when you edit a scanned PDF, Acrobat applies OCR automatically, converts it to “a fully editable copy of your PDF”, and that new text “matches the look of the original fonts in your scanned image”6; on Adobe's plans, turning scans into editable PDFs is listed for Acrobat Pro and Studio1. Smallpdf says its OCR tool turns a scan into editable text that you then change in its PDF Editor, which needs its Pro plan2. Sejda has a separate OCR tool, free for documents of up to 10 pages, that makes a scan searchable7, but its online editor says “Changing existing text within scanned documents is not supported”5.

This is the way to make many changes at once, or to rewrite whole sentences. Check two things afterwards. First the recognised words: a letter OCR misread becomes a real typo in the text you edit. Then the look of the lines you changed, beside the ones you did not.

Convert it to Word, and back to PDF

Microsoft says that when you open a PDF in Word, Word makes a copy, converting it to a Word document and “attempting to match layout of the original PDF”, that the result “might not look exactly the way it looked as a PDF”, and that conversion works best with files that are mostly text3. PDF24 gives the same advice for changing the text of a PDF: convert it to Word, edit it there, then convert it back4, and iLovePDF converts scanned PDFs to Office files8. This suits a document you will keep editing, such as a draft. Expect the layout of the new PDF to differ from the old one, and check every page of it, not only the page you changed.

CECO PDF's own PDF to Word is no different: it rebuilds plain prose as text you can edit, without the original layout and fonts, and turns any other document into pictures of its pages, and it says which it did. Editing a PDF in Word, Google Docs or Canva sets out what each of those apps changes.

Cover the word, and type over it

The quickest way is to cover the word with a white box and type the new one on top. Sejda calls this whiteout: it covers part of the page “with a white rectangle so the contents is no longer visible”5. Adobe's free online editor adds text boxes, and Adobe says it does not let you edit existing body text9. On a page saved from a word processor, with plain white paper, covering is quick. On a scan it seldom matches: the paper behind the words is not pure white, the new letters are set in a font the editor has rather than the one on the page, and they are sharper than the scan around them. And it is a cover: the pages we read do not say that the word underneath is removed. Removing text from a PDF says how to take a word out for real.

Correct the word in place, and check it

This is the way CECO PDF works. Select the word, type what it should say, and apply the correction. Where the page has real text, the new words are typed into it. On a scan they are made from the page's own letters where it has them, or drawn to match the letters around them, with the blur, the grain and the colour of the ink measured beside them, and the result says which it did. Then the page is drawn again, before and after, a scan at 300 dots per inch and a page of real text at 150, and compared pixel by pixel: the corrected file can be downloaded only once no pixel outside the corrected words has changed.

When the paper behind the words, a stamp across the line or the typeface cannot be matched, the correction is refused with its reason, and the document stays as it was. Each correction is one place: there is no replace-all, so a word that appears twenty times is twenty corrections, each checked on its own. Nothing about a correction is hidden: the file carries a record of what changed, and our measured results show how easily forensic detectors find the corrections. CECO PDF refuses identity documents at upload. Correct only documents that are yours, or that you are entitled to alter, as the terms say.

The tool's own page, Edit a scanned PDF online, takes you through it step by step, and changing a date or a number covers a figure you typed wrong in your own document.

Corrections are free, up to 10 a day, on files of up to 15 MB and 50 pages without a credit or a plan. Signed in, your first corrected download each day costs nothing; after it, one takes a credit or a plan. One corrected document costs €0.99, and a pack of 10 costs €4.99; the Personal plan is €9.99 a month or €89.99 a year, and Business €24.99 a month or €224.99 a year. Prices include VAT, and the pricing page says what each allows.

Correct a scanned PDF now — it opens the tool, with nothing to install.

What the other ways do better

Whichever way you choose, check the result

How we checked

We read each maker's own pages, listed under Sources with the day each was read: prices, product pages, help pages and their questions and answers. Every statement about another tool comes from those pages, quoted where the exact words matter, and where they do not say something, neither do we. We did not upload files to any of these tools: this compares what each maker says its tool does, not our own tests of it. Retyping and covering with white are general methods rather than products; where a product is named, its maker's own page is cited.

Prices are the ones each page showed us, in the currency it showed. They can differ by country, tax and offer, so check the maker's page before you buy. Facts about CECO PDF come from the service itself: its prices, limits and how long it keeps files are read from its own settings each time this page is served. If something here is out of date, the page is corrected and dated again.

Sources

Each page below was read on its maker's own website, on the day given beside it. A number in the text leads to the page the fact came from.

  1. Adobe: Acrobat plans and pricing, US prices. www.adobe.com/acrobat/pricing.html?country=US, read on
  2. Smallpdf: Edit PDF, and its questions and answers. smallpdf.com/edit-pdf, read on
  3. Microsoft: Opening PDFs in Word. support.microsoft.com/en-us/word/opening-pdfs-in-word, read on
  4. PDF24: Edit PDF, and its questions and answers. tools.pdf24.org/en/edit-pdf, read on
  5. Sejda: Online PDF editor. www.sejda.com/pdf-editor, read on
  6. Adobe: Edit your scanned PDF documents with OCR. www.adobe.com/acrobat/how-to/ocr-software-convert-pdf-to-text.html, read on
  7. Sejda: OCR PDF. www.sejda.com/ocr-pdf, read on
  8. iLovePDF: Frequently asked questions. www.ilovepdf.com/help/faq, read on
  9. Adobe: Acrobat online: free PDF editor. www.adobe.com/acrobat/online/pdf-editor.html, read on
  10. PDF24: PDF24 Creator. tools.pdf24.org/en/creator, read on

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