def renew(self):
        ps = subprocess.Popen('xwd -root -display virgl-host:0'.split(), stdout=subprocess.PIPE, stderr=subprocess.DEVNULL)
        output = subprocess.check_output(('xwdtopnm'), stdin=ps.stdout, stderr=subprocess.DEVNULL)
        ps.wait()

        f = io.BytesIO()
        f.write(output)
        f.seek(0)
        self.old = self.new
        img = Image.open(f)
        self.new = np.asarray(img)
        img.close()
        f.close()
        return()