def mask_roi_unique(self):
        """
        Assemble a set of unique magnitude tuples for the ROI
        """
        # There is no good inherent way in numpy to do this...
        # http://stackoverflow.com/q/16970982/

        # Also possible and simple:
        #return np.unique(zip(self.mask_1.mask_roi_sparse,self.mask_2.mask_roi_sparse))

        A = np.vstack([self.mask_1.mask_roi_sparse,self.mask_2.mask_roi_sparse]).T
        B = A[np.lexsort(A.T[::-1])]
        return B[np.concatenate(([True],np.any(B[1:]!=B[:-1],axis=1)))]