title: imagemagick convert AI file which have transparent layer to PNG
body: <p>I'm not familiar with ai file . I have a AI file which has transparent layer or alpha layer , and I try to convert this file to png with imagemagick:</p>
  
  <blockquote>
    <blockquote>
      <p>convert -resize '1000x' -density 300 test.ai test.png</p>
    </blockquote>
  </blockquote>
  
  <p>ai file url :  pan.baidu.com/s/1eQ9nS4a</p>
  
  <p>I converted image which transparency layer was lost: </p> 
  
  <p>url :  assets.baicizhan.com/test_data/test_wrong.jpg</p>
  
  <p>but the correct image should be like this:  </p> 
  
  <p>url : assets.baicizhan.com/test_data/test_right.jpg</p>
  
  <p>So what is the magic parameter I have to use here?</p>