Making a scanned sheet searchable, and repairing text that came out badly.
A PDF that was exported from CAD already carries its text, and everything that reads a sheet - search, title detection, the text markup tools - works straight away. A scan is a picture of a drawing with no text in it at all, and none of that works until the text is recovered.
OCR reads the image and puts a text layer behind it. Find it at Document > Manage Pages > Tools > OCR.
| Pass | What it does | When |
|---|---|---|
| Patch Missing Text | OCRs only the pages that have no text layer. | The usual one. A set that is mostly CAD exports with a few scanned sheets dropped in. |
| Enhance Poor Text | Re-OCRs pages whose text is low-quality or garbled. | The sheet has text, but searching it finds nothing and the title detection reads nonsense. |
| Re-OCR All Pages | Discards existing text and re-runs OCR on every page. | Last resort. It throws away good text along with bad. |
Patch Missing Text is the one to reach for first: it is the cheapest, it cannot damage text that is already good, and on a typical set it is the only one you need.
Recovered text feeds everything else that reads the sheet, so the order matters:
OCR itself is available on every subscription. Step 2, the automatic reading of title blocks, is part of the Advanced feature set - see Managing pages.
Running detection first on a scanned set finds nothing, and it is easy to conclude the detection is broken rather than that there was no text to read.