function [ axis ] = axis2df( N, pixsize)
   
%[0,0]が1+N/2にある2Dのx、y平面を作る

axis=zeros(N,N,2);     
XSize = N * pixsize;

xxxx = 0:N-1;
    yyyy = permute(xxxx,[2 1]);
    
    xxn = repmat(xxxx,N,1);
    yyn = repmat(yyyy,1,N);

        xx = XSize ./ N .* xxn - XSize ./ 2;  
        yy = (XSize ./ N .* yyn - XSize ./ 2);
        
axis(:,:,1) = yy;
axis(:,:,2) = xx;

end

