http://blog.csdn.net/zhuyonghao123/article/details/7996013
wavedec2:多层二维离散小波变换函数
[C,S] = wavedec2(X,N...,‘wname‘)
[C,S] = wavedec2(X,N,Lo_D,Hi_D)
appcoef2:二维离散小波变换低频部分系数提取
A = appcoef2(C,S,‘wname‘,N)
A = appcoef2...(C,S,‘wname‘)
A = appcoef2(C,S,Lo_R,Hi_R)
A = appcoef2(C,S,Lo_R,Hi_R,N)
detcoef2:二维离散小波变换高频部分系数提取
D =