How to Make a Scanned PDF Searchable on a Mac (On-Device OCR)
A scanned PDF is a stack of page pictures. You can read it, but your Mac can't: Spotlight finds nothing inside it, Preview's search comes up empty, and you can't copy a sentence out of it. To fix that, the text on each page has to be recognized (OCR, optical character recognition) and saved into the PDF as an invisible text layer. On a Mac you can do it without uploading the document anywhere: in Folia Files, open the PDF in PDF Tools and click Make Searchable (OCR)…. macOS reads the text on your Mac and Folia Files writes a new, searchable copy next to the original.
Here is what "searchable" really means, how to check a PDF, and the steps.
What makes a PDF searchable
A PDF can hold two very different things on a page:
- Text, stored as characters. This is what you get when you export a document from Word, Pages or a web browser. You can select it, search it, and copy it.
- Pictures of the page. This is what most scanners, scanning apps and "Save as PDF" from a photo give you. It looks the same, but for the computer it is only pixels.
A searchable scan has both: the picture you see, plus the recognized words placed invisibly at the same spots. You still see the original scan, but you can now select a line, copy it, and find the document by a word it contains.
How to tell if a PDF has a text layer
Open it in Preview and try one of these:
- Press ⌘ F and search for a word you can clearly see on the page. No result means there is no text behind it.
- Drag across a sentence. If you can't highlight words, only draw a rectangle, the page is a picture.
A PDF can also be mixed: some pages typed, others scanned and inserted later. Check a few pages, not just the first one.
Why Spotlight and Preview can't help with a scan
Spotlight indexes the text stored inside documents. A scanned PDF has none, so a search for "lease" or an invoice number finds the file only if those words are in its name. This also applies to every search tool that relies on Spotlight, Folia Files' own text search included.
Preview opens and annotates PDFs very well, but it has no command to recognize the text of a scanned page and save it into the file. Live Text may let you select words in some pictures on screen, but it doesn't write anything into the PDF, so the next search still finds nothing.
Recent versions of macOS do read the text in picture files such as a JPEG or PNG scan, and Spotlight can then find them by what they say. A PDF made of scanned pages doesn't get that treatment.
Make a scanned PDF searchable with Folia Files
Folia Files is a file manager for the Mac. Its PDF tools combine, reorder, rotate, split and compress PDFs, and make the text of scans searchable. The recognition is done by macOS (Apple's Vision framework) on your Mac: the document never leaves it, and you don't need an internet connection.
1. Open the PDF in PDF Tools
Right-click the scanned PDF in a Folia Files pane and choose PDF Tools…. The tool opens in a tab with that file already in its list. You can also open it from the menu bar (Tools › PDF Tools…) or from the Tools button of the toolbar, then add files with Add… or Pane Selection, or drop them on the pages.
2. Check the pages
The right side, Pages, shows every page as a thumbnail. Before recognizing anything:
- turn any sideways page upright with Rotate Left or Rotate Right (with no page selected, they turn them all);
- remove blank pages or pages you don't want with the trash button (the file itself isn't changed);
- reorder pages with the arrows if the scanner fed them in the wrong order.
The tool works on all the pages shown, in this order. If you checked several files, their pages are combined into one document: to make several PDFs searchable separately, do them one at a time (Clear All between two).
3. Click Make Searchable (OCR)…
Click Make Searchable (OCR)… in the bar at the bottom. When the window isn't wide enough for every button, as in the screenshot below, it is in the More Actions menu, next to Save as One PDF….
Folia Files asks where to save the result and suggests the same folder and the original name followed by "(searchable)". It then shows Recognizing text… while macOS reads each page. When it's done, Folia Files goes back to your files with the new PDF selected in its folder; the bar at the bottom of the PDF Tools tab says how many characters were recognized.
Your original PDF is never modified. The new one looks exactly the same, with the recognized text placed invisibly over each scanned page. Pages that already had text are kept as they are: only the pages without any text are recognized.
4. Search for a word to check
Spotlight needs a moment to index a new file. Then search for a word you know is in the scan: in Spotlight (⌘ Space), in Preview with ⌘ F, or in Folia Files. In Folia Files, click Find in the toolbar, choose In the text content in the menu of the button that says In the name, and type your words. Each result says why it was found.
Folia Files' search looks for every word you type, in any order, ignoring capitals and accents.
Turn photos of paper documents into one searchable PDF
PDF Tools also takes pictures: JPEG, PNG, HEIC photos of receipts, letters or contract pages. Each picture becomes a page. Add them all, put the pages in order, then click Make Searchable (OCR)…: you get a single PDF whose text you can search and copy, made only of what you photographed.
If you just want one clean PDF without recognition, Save as One PDF… does that, and Compress… often makes a PDF of photos much smaller.
What to expect from the recognition
- Languages. In the current version, Folia Files recognizes text in English, French, German, Spanish and Italian.
- Quality. Clean, straight, well-lit scans give the best results. Small print, handwriting, stamps and very faded copies may come out wrong or not at all. OCR is never perfect: search for a few words to see how well it worked.
- Layout. The visible page doesn't change: you still see the scan. Only the invisible text is added, line by line, where macOS found it.
- Time. Each page is read in turn. A few pages take seconds; a long scanned book takes longer, and you can keep working in other tabs meanwhile.
- Privacy. Nothing is sent to a server. The scan, the recognized text and the result stay on your Mac.
Other ways to do it
Adobe Acrobat Pro can recognize text in a scanned PDF, and many scanner apps can do it at scan time if you turn the option on. Online OCR services work too, but they mean uploading the document, which is rarely what you want for a contract, a pay slip or a medical letter. Folia Files is a good fit when the scans are already on your Mac and you want them searchable alongside the rest of your files, without sending them anywhere.
