Middle and middle-low subbands are chosen for watermark embedding.A selective embedding method is used to embed watermark into those coefficient blocks with clear block polarities.

• 浮水印嵌入时选择人耳较不敏感的偏低频系数作为嵌入之用，并且使用区块分类来过滤不适合嵌入浮水印的系数区块，将数位浮水印嵌入较不易改变极性之区块以确保浮水印的强韧性。