title: How to set the background color when rendering a PNG using PythonMagick
body: <p>I'm trying to render an SVG->PNG using PythonMagick, but it seems that the background color is ignored.</p>
  
  <p>Using the ImageMagick command, things work as expected:</p>
  
  <pre><code>tmp$ convert -background none access.svg access.png
  tmp$ convert -background red access.svg access2.png
  </code></pre>
  
  <p>which results in transparent and red backgrounds respectively.</p>
  
  <p>But using PythonMagick, it seems the background color is ignored:</p>
  
  <pre><code>import PythonMagick
  svg = PythonMagick.Image('access.svg')
  svg.backgroundColor().to_std_string()
  '#FFFFFFFFFFFF'
  svg.backgroundColor().alpha()
  0.0
  svg.backgroundColor('none')
  svg.backgroundColor().to_std_string()
  '#0000000000000000'
  svg.backgroundColor().alpha()
  1.0
  svg.write('access.png')
  svg.backgroundColor('red')
  svg.backgroundColor().to_std_string()
  '#FFFF00000000'
  svg.backgroundColor().alpha()
  0.0
  svg.write('access2.png')
  </code></pre>
  
  <p>Checking the output shows that both pngs have a white background. Is there another way to set the background color so that it is recognised when writing the image?</p>