code: def image(self):
          
          events = self.event_table
          skycoord = SkyCoord(events['GLON'], events['GLAT'], unit='deg', frame='galactic')
          pixcoord = PixCoord.from_sky(skycoord=skycoord, wcs=self.wcs)
  
          shape = self.config['shape']
          bins = [np.arange(shape[0] + 1), np.arange(shape[1] + 1)]
          sample = np.vstack((pixcoord.y, pixcoord.x)).T
          data, _ = np.histogramdd(sample=sample, bins=bins)
          data = data.astype('float32')
  
          header = self.wcs.to_header()
          return fits.ImageHDU(data=data, header=header, name='image')
docs: Counts image (`~astropy.io.fits.ImageHDU`).