expand.m

multi_wavelet An Image Digital Watermarking Algorithm Based on Bit-Plane-Decomposition and Multi-

%水印图像的G-P插值
function f=expand(G); 
M=size(G,1);
a=0.5;
 w=[1/4-a/2,1/4,a,1/4,1/4-a/2];
GG=zeros(2*M,2*M);
    for i=1:2*M
        for j=1:2*M 
             for m=1:5
                for n=1:5
                    W(m,n)= w(m)*w(n);
                     m1=abs(fix((i-m)/2))+1;
                     n1=abs(fix((j-n)/2))+1;
                    if m1>M
                        m1=M;
                    end
                    if  n1>M
                        n1=M;
                    end
                    
                 GG(i,j)= GG(i,j)+W(m,n)*G(m1,n1);
                end
            end
        end
    end
  f=uint8(GG);