从空间滤波器获得频率域滤波器

1、32从空间滤波器获得频率域滤波器 一、 实验目的掌握从空间滤波器获得频率域滤波器的方法二、 实验内容1. 从 Sobel 空间滤波器用 freqz2 获得频率域滤波器2. 观察空间滤波器和对应的频率域滤波器的滤波结果三、 实验步骤1. 执行如下代码,实现空间域滤波和频域滤波的比较:1 读入原始图像:clcclearf = imread('lena.jpg'imshow (ftitle('原始图像 '2 进行傅里叶变换:F = fft2(f;S = fftshift(log(1+abs(F;S = gscale(S;imshow (Stitle('傅立叶频

2、谱图像 ' 3 使用 f = im2double(f 之后再进行处理的傅立叶频谱图像 :f = im2double(f; % 转换为F = fft2(f;S = fftshift(log(1+abs(F;S = gscale(S;imshow (Stitle('使用 f = im2double(f 之后再进行处理的傅立叶频谱图像 ' 2. freqz2 P90 增强垂直边缘 sobel H = freqz2(h,PQ(1,PQ(2:1 产生的滤波器原点在矩阵中心处读入图像:clcclearf = imread('lena.jpg'imshow (f进行傅

3、里叶变换:F = fft2(f;S = fftshift(log(1+abs(F;S = gscale(S;Imshow(S增强垂直边缘:h = fspecial('sobel'' % 增强垂直边缘figure,freqz2(h; % uses n2 n1 = 64 64.PQ = paddedsize(size(f;H = freqz2(h,PQ(1,PQ(2; % 产生的滤波器原点在矩阵中心处 H1 = ifftshift(H; % 迁移原点到左上角 figure,mesh(abs(H1(1:20:400,1:20:400imshow (abs(H,imshow (

4、abs(H1,gs = imfilter(double(f,h;gf = dftfilt(f,H1;imshow (gs,imshow (gf,imshow (abs(gs,imshow (abs(gf,imshow (abs(gs > 0.2*abs(max(gs(:imshow (abs(gf > 0.2*abs(max(gf(:d = abs(gs-gf;max(d(:min(d(: 3. reqz2 P90 增强水平边缘 sobel % fft2(f 产生的频域 F 的原点在左上角 读入图像clcclearf = imread('lena.jpg'傅里叶变换

5、:F = fft2(f;S = fftshift(log(1+abs(F;S = gscale(S;h = fspecial('sobel' % 增强水平边缘figure,freqz2(h;% size_h = size(tempPQ = paddedsize(size(f;H = freqz2(h,PQ(1,PQ(2;H1 = ifftshift(H;figure,mesh(abs(H1(1:20:400,1:20:400imshow(abs(H, imshow(abs(H1, gs = imfilter(double(f,h; gf = dftfilt(f,H1; d = abs(gs-gf; max(d(: min(d(: 四、实验总结 通过本次实验， 我了解了从空