code: public Coordinate pixelsToMeters(double px, double py, int zoomLevel) {
          double res = resolution(zoomLevel);
          double mx = px * res - originShift;
          double my = -py * res + originShift;
  
          return new Coordinate(mx, my);
      }
docs: Converts pixel coordinates in given zoom level of pyramid to EPSG:3857
  
  @param px        the X pixel coordinate
  @param py        the Y pixel coordinate
  @param zoomLevel the zoom level
  @return The coordinate transformed to EPSG:3857