Flip if asked in self.flipV or self.flipH
        :param sliceimg: one image slice
        :return: flipp

def __flip(self, sliceimg):
        """
        Flip if asked in self.flipV or self.flipH
        :param sliceimg: one image slice
        :return: flipp
        """
        if self.flipH:
            sliceimg = sliceimg[:, -1:0:-1]

        if self.flipV:
            sliceimg = sliceimg [-1:0:-1,:]

        return sliceimg