title: pdfkit does not embed images in PDF
body: <p>I have an HTML file that shows images correctly. However, the PDF generated from this HTML file does not show those images. What am I missing?</p>
  
  <p>My Python code to generate PDF from HTML.</p>
  
  <pre><code>options = {
          'page-size' : 'A4',
          'dpi' : 400
      }
  css = ['../css/report.css', '../css/w3.css']
  pdfkit.from_file(htmlFilePath, pdfFilePath, options=options, css=css)
  </code></pre>
  
  <p>The HTML file (used to generate PDF) has reference to image files as shown here:</p>
  
  <pre><code>&lt;h2 class="heading"&gt;Trends of parameters and set-points&lt;/h2&gt;
  &lt;h3&gt;Trend-1&lt;/h3&gt;
  &lt;div&gt;
      &lt;img src="../png/PT-1.png"&gt;&lt;/img&gt;
  &lt;/div&gt;
  &lt;h3&gt;Trend-2&lt;/h3&gt;
  &lt;div&gt;
      &lt;img src="../png/PT-2.png"&gt;&lt;/img&gt;
  &lt;/div&gt;
  &lt;h3&gt;Trend-3&lt;/h3&gt;
  &lt;div&gt;
      &lt;img src="../png/PT-3.png"&gt;&lt;/img&gt;
  &lt;/div&gt;
  </code></pre>