title: GhostScript 'PDF to Image' makes blank image file
body: <p>Now, I'm creating a program which is generating pdf thumbnails by using C# WinForm.
  So I choose to use GhostScript to get PDF Thumbnail.
  However, GhostScript create blank image from sometimes(some pdf files).
  (only a parts of Pdf files are converted to Blank Image Files, other are correctly converted to Image file.)
  This blank image files is same image size with pdf, but it is just white image.</p>
  
  <p>And I found that these PDF files are showed a blank page in a short time when I open this files by PDF Reader.
  So I expect these pdf files have some special option(like protection??) and GhostScript also need some special option to covert it correctly.</p>
  
  <p>I'm using GhostScript.NET(<a href="https://ghostscriptnet.codeplex.com" rel="nofollow">https://ghostscriptnet.codeplex.com</a>), and my code is below.</p>
  
  <pre><code>GhostscriptVersionInfo _lastInstalledVersion = null;
  private GhostscriptRasterizer _rasterizer = null;
  int dpi = 100;
  string inputPdfPath = @"F:\pdf\155.pdf";
  _lastInstalledVersion = GhostscriptVersionInfo.GetLastInstalledVersion(GhostscriptLicense.GPL |  GhostscriptLicense.AFPL, GhostscriptLicense.GPL);
  _rasterizer = new GhostscriptRasterizer();
  _rasterizer.Open(inputPdfPath, _lastInstalledVersion, false);
  Image img = _rasterizer.GetPage(dpi, dpi, 1);
  _rasterizer.Close();
  </code></pre>
  
  <p>Please help me to solve this problem...</p>
  
  <p>In addition, I tried to use Winapi CodePack, Magik.NET.
  However, Winapi create PDF Icon, Magik.NET makes errors.(Both of them is worse than GhostScript.)</p>