function I=HaarInverseAux(I1,I2,I3,I4); 

[M,M]=size(I1); 
I=zeros(2*M,2*M); 
I(1:2:2*M,1:2:2*M)=I1;
I(1:2:2*M,2:2:2*M)=I2;
I(2:2:2*M,1:2:2*M)=I3;
I(2:2:2*M,2:2:2*M)=I4; 