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

    # Demonstrate the Image#modulate method

    blonde = Magick::Image.read('images/Blonde_with_dog.jpg').first
    blonde.scale!(300.0/blonde.rows)

    after = blonde.modulate(0.85)

    # Show before and after.
    after.crop!(after.columns/2, 0, after.columns/2, after.rows)
    result = blonde.composite(after, Magick::EastGravity, Magick::OverCompositeOp)

    # Draw a line down the middle.
    line = Magick::Draw.new
    line.line(result.columns/2, 0, result.columns/2, result.rows)
    line.draw(result)

    #result.display
    result.write('modulate.jpg')
    exit