求问怎么将长度为N/2的窗函数放到长度为N的零数组中间

MATLAB程序

defocus_aa=imread('defocus_aa.tif');

fft_aa=double(fft2(defocus_aa));

%% 加窗
defocus_aa=double(defocus_aa);
Windows_1=hanning(length(defocus_aa)/2);
% figure;
% plot(abs(Windows_1))
%改变窗函数形状

Windows_fft=fft(Windows_1,length(defocus_aa));
% Windows_fft=fft(Windows_1);
% Windows_fft1=fftshift(Windows_fft);
Windows=fftshift(Windows_fft);

Windows=ifft2(Windows);

figure;
plot(abs(Windows))

时域的窗函数图是前面是汉宁窗的形状，后面是零，现在想改成中心为汉宁窗，两边为零  qing'q