Use Tesseract to OCR a multiple page PDF
----------------------------------------


Last edited: $Date: 2018/05/30 18:39:38 $

## Tesseract to OCR

Tesseract is a  well known open source OCR engine.  It is famous for
its quality.


## ghostscript to convert PDF to tiff

First we must convert our PDF to a tiff file.

Tesseract requires image files, so first  we have to convert the PDF
to  images. When  we  use ghostscript  for this,  we  will get  high
quality images.


## Converting the PDF to tiff:

    gs -dNOPAUSE -sDEVICE=tiffg4 -r600x600 -dBATCH -sPAPERSIZE=a4 \
     -sOutputFile=output_filename.tiff input_filename.pdf


## Convert tiff to text with Tesseract 

    tesseract output_filename.tiff text_file -l eng

The file text_file will become the ouput file. Tesseract will put an
".txt" extension to the filename.


$Id: ocrwithtesseract.txt,v 1.3 2018/05/30 18:39:38 matto Exp $