# crop.rb

    #!/usr/local/bin/ruby18 -w
    require 'RMagick'

    # Demonstrate the Image#crop method

    img = Magick::Image.read('images/Flower_Hat.jpg')[0]

    # Crop the specified rectangle out of the img.
    chopped = img.crop(23, 81, 107, 139)

    # Go back to the original and highlight the area
    # corresponding to the retained rectangle.
    rect = Magick::Draw.new
    rect.stroke('transparent')
    rect.fill('white')
    rect.fill_opacity(0.25)
    rect.rectangle(23, 81, 107+23, 139+81)
    rect.draw(img)

    img.write('crop_before.png')

    # Create a image to use as a background for
    # the "after" image.
    bg = Magick::Image.new(img.columns, img.rows) {self.background_color="none"}

    # Composite the the "after" (chopped) image on the background
    bg = bg.composite(chopped, 23, 81, Magick::OverCompositeOp)

    bg.write('crop_after.png')

    exit

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