title: imageJ how to get pixel rgb value?
body: <p>i have a simple plugin which saves the polygon coordinates:</p>
  
  <pre><code>Roi roi = imp.getRoi();
  Polygon p = roi.getPolygon();
  for (int i = 1; i &lt;= p.npoints; i++) {
  // létrehozzuk az onvif féle vector-t
  org.onvif.ver10.schema.Vector myVector = new Vector();
  myVector.setX((float) p.xpoints[i - 1]);
  myVector.setY((float) p.ypoints[i - 1]);
  op.getPoint().add(myVector);
  // IJ.log("Vector X Elements " + i + " :" + MyVector.getX());
  
          }
  </code></pre>
  
  <p>but i want to get the coordinates rgb values like this:
  <img src="https://i.stack.imgur.com/FTqUe.jpg" alt="enter image description here"></p>
  
  <p>can you help me with this?
  Thank you!</p>