均值滤波

一般选取n*n的模板,便于运算,下面给出示例代码:
img = imread(''); [M , N] = size(img);%图片尺寸 img_result = zeros(M, N);%预生成,提高速度 muban_size = 3;%模板尺寸 expand_size = floor(muban_size / 2);%扩展尺寸 muban = 1 / (muban_size * muban_size) .* ones(muban_size, muban_size); expand_img = double(wextend('2D','zpd', img, expand_size));%扩展0,转double为了矩阵运算 for i=1:M for j=1:N ave = sum( sum( expand_img(i:i+muban_size-1,j:j+muban_size-1) .* muban)); %取出扩展元素与模板相乘,并求矩阵元素之和 img_result(i,j) = ave; end end img_result = uint8(img_result);%转int8,图像 subplot(1 ,2, 1); title('原图像') imshow(img) subplot(1 ,2, 2); imshow(img_result) da = ['模板大小为' num2str(muban_size) ',变化后的图像']; title(da)
中值滤波
示例代码:
img = imread(''); [M , N] = size(img);%图片尺寸 img_result = zeros(M, N);%预生成,提高速度 muban_size = 3;%模板尺寸 expand_size = floor(muban_size / 2);%扩展尺寸 muban = ones(muban_size, muban_size); expand_img = double(wextend('2D','zpd', img, expand_size));%扩展0,转double为了矩阵运算 for i=1:M for j=1:N mat = expand_img(i:i+muban_size-1,j:j+muban_size-1) .* muban; %取出x1中从(i,j)开始的n行n列元素与模板相乘 mat = mat(:);%转数组 mat = sort(mat);%排序 if mod(muban_size, 2)==1 img_result(i,j) = mat(floor(muban_size*muban_size/2)+1);%取中间 else img_result(i,j) = (mat(muban_size*muban_size/2) + mat(muban_size*muban_size/2+1))/2; end end end img_result = uint8(img_result);%转int8,图像 subplot(1 ,2, 1); title('原图像') imshow(img) subplot(1 ,2, 2); imshow(img_result) da = ['模板大小为' num2str(muban_size) ',变化后的图像']; title(da)
一些其他的中值滤波器:

另:
中值滤波的窗口形状和尺寸对滤波效果影响较大,不同的图像内容和不同的应用要求,往往采用不同的窗口形状和尺寸。常用的二维中值滤波窗口有线状、方形、圆形、十字形以及圆环形等。
窗口尺寸一般先用3X3,再取5X 5逐渐增大,直到滤波效果满意为止。就经验来讲,对于有缓变的较长轮廓线物体的图像,采用方形或圆形窗口为宜。对于包含有尖顶物体的图像,用十字形窗口,而窗口大小则以不超过图像中最小有效物体的尺寸为宜。如果图像中点、线、尖角细节较多,则不宜采用中值滤波
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