%利用頻率變換法生成一個2-D濾波器
b = firpm(10,[0 0.4 0.6 1],[1 1 0 0]);
h = ftrans2(b);
[H,w] = freqz(b,1,64,'whole');%得到b的1-D頻率響應
colormap(jet(64))%圖形顏色映射
plot(w/pi-1,fftshift(abs(H)))
figure, freqz2(h,[32 32])