title: TCPDF Image aspect ratio issue
body: <p>I have an issue with TCPDF Image inserting.</p>
  
  <p><img src="https://i.stack.imgur.com/aGLtV.png" alt="enter image description here"></p>
  
  <p>Here's the code i'm using :</p>
  
  <pre><code>$this-&gt;Image($this-&gt;data['logo'], PDF_MARGIN_LEFT, 5, 60, 20, '', '', 'M', true);
  </code></pre>
  
  <p>I've set the resize at true, but the TCPDF library do not respect image ratio.</p>
  
  <p>How can I force preserving image ratio ?</p>
  
  <p>For information I'm using TCPDF 6.2.8 (2015-04-29).</p>
  
  <p>Thanks for your support,
  David.</p>