title: Convert a pdf to tiff with abcpdf gives a black polygon in the result
body: <p>We have a PDF document which we want to convert to a TIF file. The pdf contains a box with a light gray background. When converting this gray turns into a black polygon in the tif. No matter what Rendering settings it will always be black. Is there anything what I can do to influence the rendering to TIF so this gray box does not turn into black? We use the following code:</p>
  
  <pre><code>        using ( Doc doc = new Doc() )
          {
              XReadOptions options = new XReadOptions { ReadModule = ReadModuleType.Pdf };
  
              doc.Read( bytes, options );
  
              using ( MemoryStream ms = new MemoryStream() )
              {
                  int n = doc.PageCount;
                  for ( int i = 1; i &lt;= 1; i++ )
                  {
                      doc.PageNumber = i;
  
                      doc.Rect.String = doc.CropBox.String;
                      doc.Rendering.SaveAppend = ( i != 1 );
  
                      doc.Rendering.Save( "out.tif", ms );
                  }
  
                  byte[] tifBytes = ms.GetBuffer();
                  File.WriteAllBytes( string.Format( @"{0}\total.tif", workingFolder), tifBytes );
              }
          }
  </code></pre>