中文说明：对于纯奇异值分解算法，
English Description：
In case of pure SVD based algorithms, watermark is embedded in the SVD domain only whereas in hybrid SVD based algorithms, watermark is embedded in the SVD and transform domain. There are two types of pure SVD based algorithms where in some watermarking schemes watermark is embedded into the whole cover image and in some other schemes the cover image is divided into several blocks and the watermark is embedded into each block of the cover image separately.