# viewex.rb

    #!/usr/local/bin/ruby18 -w

    require 'RMagick'

    img = Magick::Image.new(40, 40) {self.background_color = 'lightcyan2'}

    # The view is 400 pixels square, starting
    # column 10, row 5 from the top of the image.
    img.view( 10, 5, 20, 20) do |view|

        # Set all the pixels in the view to green.
        view[][] = Magick::Pixel.new(0, Magick::QuantumRange)

        # Change the top and bottom rows to red.
        view[0][] = 'red'
        view[-1,1][] = 'red'

        # Set 6 pixels to black.
        view[[13,15]][[12,14,16]] = 'black'

        # Set 1 pixel to yellow.
        view[5][7] = 'yellow'

        # Change the green channel of all the
        # pixels on row 8.
        view[8][].green = Magick::QuantumRange/2

        # Change the blue channel of 8 pixels
        # on column 10.
        view[4,8][10].blue = Magick::QuantumRange
    end

    img.scale(5).write("viewex.gif")
    exit

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