A novel theorem linking reflectional symmetry and rotational symmetry has b
een established in this paper. This theorem constrains that, for a rotation
ally symmetric image with K greater than or equal to1 fold(s) (K-RSI), its
number of reflection-symmetric axes must be either K or zero. The novel con
straint theorem provides the guidance for the procedure of symmetry detecti
on. It has been demonstrated by the experiments included in this paper. (C)
2001 SPIE and IS&T.