说明：  对二维信号（例如二维图像），实现多级小波的分解和重构，用到的小波函数是 DBN 小波,即Daubechies小波。
(Of two-dimensional signal (such as two-dimensional image), the realization of multi-level wavelet decomposition and reconstruction, the wavelet function is used wavelet DBN, namely Daubechies wavelet.)