def expectScreen(self, filename, maxrms=0):
        """ Wait until the display matches a target image

            filename: an image file to read and compare against
            maxrms: the maximum root mean square between histograms of the
                    screen and target image
        """
        log.debug('expectScreen %s', filename)
        return self._expectFramebuffer(filename, 0, 0, maxrms)
Wait until the display matches a target image

            filename: an image file to read and compare against
            maxrms: the maximum root mean square between histograms of the
                    screen and target image