def METHOD_NAME(self):
    """Counts image (`~astropy.io.fits.ImageHDU`)."""
    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')