def roberts(image, mask=None):
 assert_nD(image, 2)
 out = np.sqrt(((roberts_pos_diag(image, mask) ** 2) + (roberts_neg_diag(image, mask) ** 2)))
 out /= np.sqrt(2)
 return out

def roberts ( image , mask = None ) : assert_nD ( image , 2 ) out = np . sqrt ( ( ( roberts_pos_diag ( image , mask ) ** 2 ) + ( roberts_neg_diag ( image , mask ) ** 2 ) ) ) out /= np . sqrt ( 2 ) return out
find the edge magnitude using roberts cross operator .