title: Extract images of signatures contained in a pdf file with iTextSharp library
body: <p>I have a signed PDF file. With this function, which makes use of iTextSharp library, I find the certificates p7m signatures:</p>
  
  <pre><code>        private void GetSignature(string FileName)
      {
          AcroFields acroFields = new PdfReader(FileName).AcroFields;
          List&lt;string&gt; names = acroFields.GetSignatureNames();
  
          foreach (var name in names)
          {
              PdfDictionary dict = acroFields.GetSignatureDictionary(name);
              PdfString contents = (PdfString)PdfReader.GetPdfObject(dict.Get(PdfName.CONTENTS));
  
              byte[] PKCS7 = contents.GetOriginalBytes();
              ByteArrayToFile(@"c:\signature\" + name + ".p7m", PKCS7);
  
          }
      }
  </code></pre>
  
  <p>Now... how can I extract images (bitmap) associated to the signatures? Is it possible?
  Thanks, Luigi</p>