    #! /usr/local/bin/ruby -w
    require 'RMagick'

    # Demonstrate the Image#stegano method.

    # Create a small watermark from the Snake image by
    # shrinking it and converting it to B&W.
    watermark = Magick::Image.read('images/Snake.wmf').first
    watermark = watermark.scale(64.0/watermark.rows)
    watermark = watermark.quantize(256, Magick::GRAYColorspace)
    wmrows = watermark.rows
    wmcols = watermark.columns

    # Read the image in which we'll hide the watermark.
    jj = Magick::Image.read('images/Jean_Jacket.jpg').first
    jj = jj.scale(250.0/jj.rows)

    # Embed the watermark starting at offset 91.
    puts 'Embedding watermark...'
    stegano = jj.stegano(watermark, 91)

    # Write the watermarked image in PNG format. Note that
    # the format must be lossless - Image#stegano doesn't work
    # with lossy formats like JPEG.
    stegano.write('jj.png')

    # Read the image and retrieve the watermark. The size
    # attribute describes the size and offset of the watermark.

    puts 'Retrieving watermark. This may take a few seconds...'
    stegano = Magick::Image.read('stegano:jj.png') {
        self.size = "#{wmcols}x#{wmrows}+91"
    }

    # We don't need this any more.
    File.delete('jj.png')

    #stegano[0].display
    stegano[0].write('stegano.gif')
    exit