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Mac Preview OCR Limitations: What It Can and Can't Reach

By Eduard Bruch, developer of Optic · Updated

Preview can recognize text in images thanks to Live Text, but it only works inside the files Preview opens, and results depend on how clean the image is. For text in other apps, video frames, dialogs or remote sessions, Preview cannot help, and you need a tool that reads the screen.

Short answer: use Preview's Live Text for clean images and scans you already have as files. For text anywhere else on screen, my pick is Optic, a menu bar app that copies the text in any area you drag across the screen ($4.99, a one-time purchase on the Mac App Store).

Disclosure: I build Optic.

What Preview does well

Preview is the Mac's default viewer for images and PDFs. With Live Text, you can often select text in a photo or screenshot with the pointer and copy it, just like text in a document. For many everyday images, that is all you need, and it is free.

Live Text works where Apple supports it: images in Preview, Photos, Quick Look and Safari, and paused video frames in some players. It does not work on arbitrary app windows, video calls or UI text.

Where Preview stops

It only reads files. Preview works on documents you open in it. Text in a running app, an error dialog, a web app, a video call or a remote desktop window is not a file, so Preview never sees it. This is the biggest gap and the most common reason people look for another tool.

Results depend on the source. Recognition quality depends on resolution, contrast and layout. A crisp screenshot usually works; a faint photo of a crumpled receipt or a dense multi-column scan may give partial results or nothing selectable. That is true of any OCR, not only Preview.

Selecting a precise area can be fiddly. In a busy page, selecting exactly one column or one value with the text cursor can pull in neighbouring text.

Scanned PDFs are mixed. Some PDFs have a text layer and select normally. A pure image scan relies on recognition, and how well that goes varies. More in copy text from a non-selectable PDF on Mac.

For a closer look at Live Text itself, see Mac Live Text limitations.

Reading text from the whole screen with Optic

Optic works at the screen level instead of the file level. Whatever is visible, in Preview or any other app, can be captured.

  1. Show the text on screen: a document in Preview, an app window, a paused video.
  2. Click the Optic icon in the menu bar and choose Capture Text.
  3. Drag a box over exactly the part you want.
  4. Paste with Command-V.

Because you draw the box, you decide what is included. Drag over one column, one paragraph or one value, and only that area is read. Optic uses Apple's Vision text recognition at its "accurate" level, on the Mac, with no internet needed.

A few settings help with documents:

  • Line breaks: keep them (default), remove them, or Smart merge to join wrapped lines while keeping sentence ends.
  • Trim whitespace: on by default.
  • Code mode: keeps indentation and turns off language correction, for code in screenshots.

Where Optic does not fit

Optic fills the "not a file" gap, but it does not replace a document OCR tool:

  • No file opening. Optic does not import images or PDFs. Open them in Preview first, then capture.
  • No whole-document OCR. It reads the area you drag, not every page of a PDF, and it does not create searchable PDFs.
  • No batch. One capture per drag.
  • No table extraction. Tables come out as lines of text, not cells.
  • Handwriting. Not a feature; do not count on it.

If you need to make a 40-page scan searchable, a document OCR app is the right tool. If you need one paragraph from page 12, or text Preview cannot reach at all, a screen OCR app is quicker.

FAQ

Can Preview do OCR on Mac?

Yes, to a degree. Live Text in Preview lets you select text in many images and scans. It works only on files you open in Preview.

Why can't I select text in an image in Preview?

Live Text may not recognize low-quality, small or complex text, and it needs a supported Mac and language. If selection fails, try a screen OCR app on the same image.

Can Preview copy text from other apps?

No. Preview only works on files it opens. For text in other app windows, dialogs or videos, you need a screen OCR app.

Does Optic make PDFs searchable?

No. Optic copies text from the area you select to the clipboard. It does not create searchable PDFs or process whole documents.

Get Optic on the Mac App Store · All Optic facts. Optic needs macOS 14 Sonoma or later. For other options, see screen OCR apps for Mac.