Blog · Sep 12, 2020

Manually adding an OCR layer to scanned PDF

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(Summary: How to add an invisible text layer to a PDF containing scanned images, using an OCR tool—in this case Google Cloud Vision API—that also gives the position of each recognized word.) Background Exploration JSON response TeX side of things Results Background Situation: A printed book has been scanned into images, possibly assembled into a single PDF. As each page is just a picture, no text…

(Summary: How to add an invisible text layer to a PDF containing scanned images, using an OCR tool—in this case Google Cloud Vision API—that also gives the position of each recognized word.)

Background
Exploration
- JSON response
- TeX side of things
Results

Background

Situation: A printed book has been scanned into images, possibly assembled into a single PDF. As each page is just a picture, no text has been associated with it, and it is not searchable. To get there, either we need the text to be typed in manually by someone, or we need OCR. Either way, many errors are likely, so when we open the PDF we’d still like to see the scanned image, except that it would be nice if the text can be selected and copied (and also searched).

Read on /post/add-ocr-layer-to-pdf/ ↗

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