Install Tesseract-OCR in Ubuntu

Installation

• Tesseract OCR

sudo apt-get install tesseract-ocr

• Install imagemagick to convert PDF to TIFF

sudo apt-get install imagemagick

• Install poppler-utils (pdfinfo) to check number of pages of PDF

sudo apt-get update
sudo apt-get install poppler-utils

• Install Other Languages

Download from https://code.google.com/p/tesseract-ocr/downloads/list
Put it in /usr/share/tesseract-ocr/tessdata

Shell Script to OCR PDF

#!/bin/sh
STARTPAGE=1 # set to pagenumber of the first page of PDF you wish to convert
RESOLUTION=600 # set to the resolution the scanner used (the higher, the better)

dumphelp(){
        echo "sudo $0  
 "
        echo "language (optional): default eng, other possible "
        echo "ara (Arabic), aze (Azerbauijani), bul (Bulgarian), cat (Catalan), ces
       (Czech), chi_sim (Simplified Chinese), chi_tra (Traditional Chinese),
       chr (Cherokee), dan (Danish), dan-frak (Danish (Fraktur)), deu
       (German), ell (Greek), eng (English), enm (Old English), epo
       (Esperanto), est (Estonian), fin (Finnish), fra (French), frm (Old
       French), glg (Galician), heb (Hebrew), hin (Hindi), hrv (Croation), hun
       (Hungarian), ind (Indonesian), ita (Italian), jpn (Japanese), kor
       (Korean), lav (Latvian), lit (Lithuanian), nld (Dutch), nor
       (Norwegian), pol (Polish), por (Portuguese), ron (Romanian), rus
       (Russian), slk (Slovakian), slv (Slovenian), sqi (Albanian), spa
       (Spanish), srp (Serbian), swe (Swedish), tam (Tamil), tel (Telugu), tgl
       (Tagalog), tha (Thai), tur (Turkish), ukr (Ukrainian), vie (Vietnamese)"
        exit 1
}

if [ $# -lt 2 ]; then
        dumphelp
fi

SOURCE=$1 # set to the file name of the PDF
OUTPUT=$2 #set to the final output file


LANGUAGE="eng"

if [ $# -eq 3 ]; then
LANGUAGE=$3
fi

ENDPAGE=`pdfinfo $SOURCE | grep Pages | sed 's/ //g' | cut -d':' -f2`
echo $STARTPAGE $ENDPAGE

touch $OUTPUT
for i in `seq $STARTPAGE $ENDPAGE`; do
    convert -monochrome -density $RESOLUTION $SOURCE\[$(($i - 1 ))\] page.tif
    echo processing page $i
    tesseract -l $LANGUAGE page.tif tempoutput
    cat tempoutput.txt >> $OUTPUT
done