function Gmat = formGmat(g, B)
%Usage:   Gmat = formGmat(g,B);
%Inputs: g is the input image row
% B is the kernel size(BxB)
%
%Output Gmat: The matrix for convolution with image row
%g could be row or column vector
if (size(g,1)==1) %g is a row vector
    gp = g;
elseif (size(g,2)==1) %g is a column vector
        gp = g';
    else
        disp('Error: g must be a column or row vector')
        exit(1);
   
end

A = max(size(g,1) ,size(g,2)) ;

g_augment = [ gp zeros(1,B-1)]';
for i = 1:B
Gmattmp(1:A+B-1,i) = circshift(g_augment,i-1);
end
Gmat = Gmattmp(B:A,1:B);