title: Poor image quality in itext
body: <p>I am using itext7 to create pdf file
  ,and at the footer I am trying to add png images as follows:</p>
  <pre><code>PdfDocumentEvent documentEvent = (PdfDocumentEvent) event;
  PdfPage page = documentEvent.getPage();
  PdfCanvas canvas = new PdfCanvas(page);
  byte[] signature = null; // retrieved from database
  PngImageData imageData = (PngImageData) ImageDataFactory.createPng(signature);
  canvas.addImageAt(imageData, 5f, 25f, false);
  </code></pre>
  <p>the original image itself has good resolution, but when the image is added to the pdf it appears with poor quality although I am adding the image without any changes or scaling.</p>
  <p>how can I improve the image quality in the final pdf ?</p>