一幅图像的傅立叶谱.m

一幅图像的傅立叶谱 tupiandefuliyebhuan

thetax=linspace(-0.5,0.5,300)*pi;
thetay=linspace(-0.5,0.5,300)*pi;
k1=4; %K1=a/λ
k2=6; %K2=b/λ
x=k1*sin(thetax)*pi;
y=k2*sin(thetay)*pi;
[x,y]=meshgrid(x,y);
z=(sin(x).*sin(y)./(x.*y)).^2;
mesh(x,y,z)
figure
imshow(z,[0.002,0.01])


syms L z k   %三角脉冲的傅立叶变换
L=1
f1=(z+L)*exp(-i*k*z)
A1=int(f1,z,-L,0)
f2=(-z+L)*exp(-i*k*z)
A2=int(f2,z,0,L)
A=A1+A2
ezplot(A,[-20,20])

 %衍射光栅的光强
theta=linspace(-0.5,0.5,100000)*pi+eps;    
lamda=6328*10^(-10);
a=0.000002;
b=0.000003;
N=10
u=pi*a*sin(theta)/lamda;
v=pi*(a+b)*sin(theta)/lamda;
subplot(3,1,1)
plot(theta,(sin(N*v).^2)./(sin(v).^2))
subplot(3,1,2)
plot(theta,(sin(u).^2)./(u.^2))
subplot(3,1,3)
I=((sin(u).^2)./(u.^2)).*((sin(N*v).^2)./(sin(v).^2));
plot(theta,I)

%本例演示一幅图像的傅立叶谱
cd g:\matlab\shztxcl
a=imread('flower.jpg');
fxy=a(:,:,3);
subplot(1,2,1),imshow(fxy,[]),title('f(x,y)')
Fuv=fft2(fxy);
Fuv=abs(fftshift(Fuv));
subplot(1,2,2),imshow(Fuv,[0,30000]),title('|F(u,v)|')
figure
mesh(Fuv),title('|F(uv)|，中心高度为∑f(x,y)')



%用绘制多光束透射干涉强度分布曲线，演示ezplot（）函数
syms derta 
for ruo=0.1:0.1:1 %反射率从0.1递增到1
f=(1-ruo).^2\4*ruo %精细度系数 
I=1/(1+f*(sin(derta/2))^2) %透射光强
ezplot(I,[0,6*pi])
hold on %在同一个图形窗口中绘制多条曲线
end
axis([0,6*pi,-0.2,1.2]) %定制坐标范围

%用菲涅尔公式演示符号绘图函数ezplot（）的使用
syms thita1 thita2
thita2=asin(sin(thita1)/1.5) %用折射定律给出 thita2
%定义S波的反射系数rs
rs=(cos(thita1)-1.5*cos(thita2))/(cos(thita1)+1.5*cos(thita2))
ezplot(thita1,rs,[0,pi/2]) %绘制反射系数rs在θ1从0到π/2之间的曲线
hold on
%定义p波的反射系数rp
rp=(1.5*cos(thita1)-cos(thita2))/(1.5*cos(thita1)+cos(thita2))
ezplot(thita1,rp,[0,pi/2]) %绘制反射系数rp在θ1从0到π/2之间的曲线
hold off


syms k K w W E A z t  %不同频率的叠加
w1=20;
w2=18;
a=3;
l=1;
k1=w1/l;
k2=w2/l;
K=(k1+k2)/2;
k=(k1-k2)/2;
W=(w1+w2)/2;
w=(w1-w2)/2;
t=1.5;
A=2*a*cos(k*z-w*t);
E=A*cos(K*z-W*t);
ezplot(E,[0.001,10]);