Take a PDF, OCR it, and add OCR Text as background layer to original PDF to make it searchable

ocrpdf.sh

#!/bin/sh

# Take a PDF, OCR it, and add OCR Text as background layer to original PDF to make it searchable.
# Hacked together using tips from these websites:
#      http://www.jlaundry.com/2012/ocr-a-scanned-pdf-with-tesseract/
#      http://askubuntu.com/questions/27097/how-to-print-a-regular-file-to-pdf-from-command-line
# Dependencies: pdftk, tesseract, imagemagick, enscript, ps2pdf
# Would be nice to use hocr2pdf instead so that the text lines up with the PDF image.
#      http://www.exactcode.com/site/open_source/exactimage/hocr2pdf/

cp $1 $1.bak
pdftk $1 burst output tesspage_%02d.pdf
for file in `ls tesspage*`
do
    PAGE=$(basename "$file" .pdf)
  # Convert the PDF page into a TIFF file
    convert -monochrome -density 600 $file "$PAGE".tif
  # OCR the TIFF file and save text to output.txt
    tesseract "$PAGE".tif output
  # Turn text file outputed by tesseract into a PDF, then put it in background of original page
    enscript output.txt -B -o - | ps2pdf - output.pdf && pdftk $file background output.pdf output new-"$file"
  # Clean up
    rm output*
    rm "$file"
    rm *.tif
done
pdftk new* cat output $1

Make sure you read this script before using. Removes stuff via. wildcards.

tesseract can now produce PDF with embedded text directly using the PDF config option. It's used something like this:

tesseract input.tif outputbase pdf

which would create outputbase.pdf

tesseract can now produce PDF with embedded text directly using the PDF config option. It's used something like this:

tesseract input.tif outputbase pdf

which would create outputbase.pdf

scruss,
Thank you for stating that! That simplifies the process significantly! Plus I now have all the packages on our server needed to convert PDFs to embedded text PDFs. I do not have to go through our IT approval process to get ocrmypdf installed, tesseract can do it.
Thanks!

I would say that the most modern variant is ocrmypdf, which is a nice wrapper above tesseract and is adding some extra features. Its natively in linux repos.

ocrmypdf

That's what I mostly use now. But this gist served me well for years

I would say that the most modern variant is ocrmypdf, which is a nice wrapper above tesseract and is adding some extra features. Its natively in linux repos.

Available...yes and no. ocrmypdf isn't available on all corporate repos, but tesseract is more available. I ran into this at a former workplace that did a lot of DoD type work and had a pretty restrictive Linux VM. ocrmypdf wasn't readily available, however tesseract was.