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

    # Demonstrate the Image#blur_image method

    lighthouse = Magick::Image.read('images/Lighthouse.jpg').first

    # Crop to the interesting part of the picture.
    lighthouse = lighthouse.crop(202, 184, 206, 230)

    # Make a blurry copy.
    blurry = lighthouse.motion_blur(0,7,90)

    # Crop the copy, retaining only the right half.
    blurry = blurry.crop(blurry.columns/2, 0, blurry.columns/2, blurry.rows)

    # Composite the copy over the right half of the original.
    result = lighthouse.composite(blurry, Magick::EastGravity, Magick::OverCompositeOp)

    # Draw a white line down the middle to emphasize the
    # border between the original image and the blurry image.
    line = Magick::Draw.new
    line.stroke('white')
    line.stroke_width(1)
    line.line(lighthouse.columns/2, 0, lighthouse.columns/2, lighthouse.rows)
    line.draw(result)

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