title: .png file not saving correctly matplotlib
body: <p>While saving a multiple grid figure in png with 300 as dpi, I lose quality</p>
  
  <p>However this error does not occur while saving the figure as a pdf. </p>
  
  <p>Here is the small portion of the code that saves the image generated:</p>
  
  <pre><code>fig.savefig(filepath, format = 'pdf'
               ,bbox_inches='tight',dpi=300)
  
  fig.savefig(filepath, format = 'png'
               ,bbox_inches='tight',dpi=300)
  </code></pre>
  
  <p>Is there a way to obtain a good resolution png of an image such as the above without having to resort to using pdf?</p>