steganography.rb

# -*- coding: utf-8 -*-
require 'RMagick'
include Magick

arr = []
embedded = ImageList.new('embedded.png')
(0...embedded.rows).each {|y|
  (0...embedded.columns).each {|x|
    pixel = embedded.pixel_color(x, y)
    arr << (((pixel.red   & 0x07) << 5) |
            ((pixel.green & 0x03) << 3) |
            (pixel.blue & 0x07))
  }
}
puts arr.reject!(&:zero?).pack('C*').force_encoding('utf-8')