tesseract-ocr info

rails gem

https://github.com/meh/ruby-tesseract-ocr

How to install Tesseract OCR on a Amazon EC2 (Free Tier) Linux Machine for Optical Character Recognition

http://alangunning.ie/2013/01/13/how-to-install-tesseract-ocr-on-a-amazon-ec2-free-tier-linux-machine-for-optical-character-recognition/

Free Online OCR Tool

http://www.online-code.net/ocr.html

Using Non-Ruby Programs With Ruby

http://ruby.bastardsbook.com/chapters/external-programs/

Tesseracting + ImageMagcking

To review, you'll have to install the following software in order to create a Ruby script that optimizes scanned images and uses Tesseract to extract their textual content:

1. The ImageMagick, a library used for command-line image manipulation
2. The RMagick gem, which provides a Ruby interface for ImageMagick
3. Tesseract, an open source OCR program that runs from the command-line

Here's example code. Understanding it requires being familiar with RMagick, but there's not much more to it than that. Here is what the code does:

1. Opens an image file
2. Optimizes the image for OCR by straightening it and creating a grayscale version that is saved to disk as a TIFF
3. Executes tesseract from the command line
4. Reads the contents of the text file created by tesseract

require 'rubygems'
require 'rmagick'

def tessrack(oimg_name, do_gray=true, keep_temp=true)
   fname = oimg_name.chomp(File.extname(oimg_name))
   
   # create a non-crooked version of the image
   tiff = Magick::Image::read(oimg_name).first.deskew 

   # convert to grayscale if do_gray==true
   tiff = tiff.quantize(256, Magick::GRAYColorspace) if do_gray == true
   
   # create a TIFF version of the file, as Tesseract only accepts TIFFs
   tname = "#{fname}--tesseracted.tif"
   tiff.write(tname){|t| t.depth = 8}
   puts "TR:\t#{tname} created"
    
   # Run tesseract
   tc = "tesseract #{tname} #{fname}"
   puts "TR:\t#{tc}"
   `#{tc}`
   
   File.delete(tname) unless keep_temp==true
   File.open("#{fname}.txt"){|txt| txt.read}
end

txt = tessrack("data-hold/tufte-intro.tif")
puts txt

FAQ

https://github.com/tesseract-ocr/tesseract/wiki/FAQ