background_image.xml

<mugl>
  <background color="0xcccccc">
    <img src="http://upload.wikimedia.org/wikipedia/commons/thumb/7/79/NOAA_logo.svg/200px-NOAA_logo.svg.png" frame="plot" anchor="0,0" base="0,0"/>
  </background>
  <window margin="0" padding="0" border="5" bordercolor="0x000000"/>
  <plotarea margintop="10" marginleft="238" marginbottom="35" marginright="35" border="3" bordercolor="0x00ff0f"/>
  <horizontalaxis id="x" min="0" max="10" length="1-40" base="0,0" anchor="0" color="0xff0000"/>
  <horizontalaxis id="x" min="0" max="10" base="-1,-1"/>
  <verticalaxis   id="y"  min="0" max="10" length="1-20"/>
  <verticalaxis   id="y2" min="0" max="10" length="1-20" base="0,-1"/>
  <verticalaxis   id="y3" min="0" max="10" length="1-20" base="1,-1"/>

  <plot>
    <horizontalaxis ref="x">
      <variable ref="x"/>
    </horizontalaxis>
    <verticalaxis ref="y">
      <variable ref="y"/>
    </verticalaxis>
    <renderer type="line">
    </renderer>
  </plot>
  <data>
    <variables>
      <variable column="0" id="x"/>
      <variable column="1" id="y"/>
    </variables>
    <values>                                                                         
      1,2
      3,4
      5,6
    </values>
  </data>
</mugl>