本文系《数字图像处理原理与实践（MATLAB版）》（电子工业出版社）一书之代码系列的Part2（P43~P135），代码执行结果请参见原书配图。
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P44
i = imread('theatre.jpg');i = rgb2gray(i);
i = double(i);
out1 = log(1+i)/0.065;
out2 = log(1+i)/0.035;
out1(find(out1>255)) = 255;
out2(find(out2>255)) = 255;
out1 = uint8(out1);
out2 = uint8(out2);
subplot(221), imshow(out1), title('image, p = 0.065');
subplot(222), imhist(out1), title('histgram, p = 0.065');
subplot(223), imshow(out2), title('image, p = 0.035');
subplot(224), imhist(out2), title('histgram, p = 0.035');
P47
i = rgb2gray(imread('theatre.jpg'));i = double(i);y1 = 255*(i/255).^2.5;y2 = 255*(i/255).^0.4;y1 = uint8(y1);y2 = uint8(y2);subplot(221), imshow(y1), title('p =2.5');subplot(222), imhist(y1), title('p =2.5');subplot(223), imshow(y2), title('p =0.4');subplot(224), imhist(y2), title('p =0.4');
P48
i = rgb2gray(imread('theatre.jpg'));y1 = double(i);y1 = 255*(y1/255).^2.5;y2 = uint8(y1);y3 = imadjust(y2, [ ], [ ], 0.4);subplot(131), imshow(i), title('original image');subplot(132), imshow(y2),title('power = 2.5');subplot(133), imshow(y3),title('gamma = 0.4');
P49
i = imread('theatre.jpg');i = rgb2gray(i);i = double(i);y1 = 1.5.^(i*0.070)-1;y2 = 1.5.^(i*0.050)-1;y1(find(y1>255)) = 255;y2(find(y2>255)) = 255;y1 = uint8(y1);y2 = uint8(y2);subplot(221), imshow(y1), title('c=0.070');subplot(222), imhist(y1), title('c=0.070');subplot(223), imshow(y2), title('c=0.050');subplot(224), imhist(y2), title('c=0.050');
P52
i = imread('theatre.jpg');i = rgb2gray(i);L = imadjust(i,[ ],[50/255;150/255]);J = imadjust(L,[50/255;150/255 ],[20/255;230/255]);subplot(221), imshow(L), title('low contrast');subplot(222), imhist(L), title('low contrast');subplot(223), imshow(J), title('gray stretch');subplot(224), imhist(J), title('gray stretch');
P54
i = rgb2gray(imread('theatre.jpg'));LC = imadjust(i,[ ],[50/255;150/255]);figure(1), subplot(221), imshow(LC);title('low contrast');figure(1),subplot(222), imhist(LC);title('low contrast');HE1 = histeq(LC);figure(1), subplot(223), imshow(HE1);title('histogram equalization');figure(1),subplot(224), imhist(HE1);title('histogram equalization');
P56
img = rgb2gray(imread('theatre.jpg'));img_ref = rgb2gray(imread('rpic.jpg'));[hgram, x] = imhist(img_ref);J = histeq(img, hgram);subplot(2,3,1), imshow(img), title('original image');subplot(2,3,4), imhist(img), title('original image');subplot(2,3,2), imshow(img_ref), title('reference image');subplot(2,3,5), imhist(img_ref), title('reference image');subplot(2,3,3), imshow(J), title('output image');subplot(2,3,6), imhist(J), title('output image');
P64-1
I = imread('apostles.jpg');I = double(I);B = zeros(size(I));H = size(I);move_x = 100;move_y = 150;B(move_y + 1:H(1), move_x+1:H(2), 1:H(3))=...I(1:H(1)-move_y, 1:H(2) - move_x, 1:H(3));subplot(1,2,1),subimage(uint8(I))title('原图像')subplot(1,2,2),subimage(uint8(B))title('平移变换');
P64-2
I = imread('apostles.jpg');se=translate(strel(1),[150 100]);B = imdilate(I,se);figure;subplot(1,2,1),subimage(I);title('原图像');subplot(1,2,2),subimage(B);title('平移变换');
P66
I = imread('apostles.jpg');[height, width, dim]=size(I);%水平镜像变换tform = maketform('affine',[-1 0 0;0 1 0; width 0 1]);B=imtransform(I, tform, 'nearest');%垂直镜像变换tform2 = maketform('affine', [1 0 0; 0 -1 0; 0 height 1]);C=imtransform(I, tform2, 'nearest');subplot(1,3,1),imshow(I);title('原图像');subplot(1,3,2),imshow(B);title('水平图像');subplot(1,3,3),imshow(C);title('垂直图像');
P67
A = imread('apostles.jpg');A = double(A);figure(1), imshow(uint8(A));H = size(A);figure(2),B(1:H(1),1:H(2),1:H(3))=A(H(1):-1:1,1:H(2),1:H(3));%垂直镜像imshow(uint8(B));figure(3),C(1:H(1),1:H(2),1:H(3))=A(1:H(1),H(2):-1:1,1:H(3));%水平镜像imshow(uint8(C));
P69
I = imread('apostles.jpg');tform = maketform('affine',[0 1 0; 1 0 0; 0 0 1]);%定义转置矩阵B = imtransform(I, tform, 'nearest');subplot(1,2,1),imshow(I)title('原图像');subplot(1,2,2),imshow(B)title('转置图像');
P74
I = imread('C:\apostles.jpg');A = imresize(I, 1.5, 'nearest');B = imresize(I, 1.5, 'bilinear');C = imresize(I, 1.5, 'bicubic');subplot(2,2,1), imshow(I), title('original');subplot(2,2,2), imshow(A), title('nearest');subplot(2,2,3), imshow(B), title('bilinear');subplot(2,2,4), imshow(C), title('bicubic');
P80
I = imread('apostles.jpg');A = imrotate(I, 30, 'nearest');%旋转30度,最邻近插值figure(1),imshow(A)B = imrotate(I, 45, 'bilinear','loose');%旋转45度，二次线性插值figure(2),imshow(B)
P92
i = imread('Hepburn.jpg');%注意w和h1这两个模板是等价的w = [1 1 1;1 1 1;1 1 1]/9;h1 = fspecial('average', [3 3]);h2 = fspecial('average', [5 5]);h3 = fspecial('average', [7 7]);%执行图像的简单平滑g1 = imfilter(i, w, 'conv', 'replicate');g2 = imfilter(i, h2, 'conv', 'replicate');g3 = imfilter(i, h3, 'conv', 'replicate');
P98
i = imread('baboon.jpg');h = fspecial('gaussian', 7, 2);g = imfilter(i, h,'conv');subplot(121), imshow(i), title('original image');subplot(122), imshow(g), title('gaussian smooth');
P103
i = rgb2gray(imread('lena.jpg'));i_noise = imnoise(i, 'salt & pepper');w1 = [1 2 1; 2 4 2; 1 2 1]/16;output1 = imfilter(i_noise, w1, 'conv', 'replicate');w2 = [1 1 1; 1 1 1; 1 1 1]/9;output2 = imfilter(i_noise, w2, 'conv', 'replicate');output3 = medfilt2(i_noise, [3, 3]);
P106
function B = bfilter2(A,w,sigma) % 针对灰度图像或彩色图像选择应用不同的处理函数if size(A,3) == 1 B = bfltGray(A,w,sigma(1),sigma(2));else B = bfltColor(A,w,sigma(1),sigma(2));end % 对灰度图像进行双边滤波处理的函数function B = bfltGray(A,w,sigma_d,sigma_r) % 计算高斯模板[X,Y] = meshgrid(-w:w,-w:w);G = exp(-(X.^2+Y.^2)/(2*sigma_d^2)); % 进行双边滤波dim = size(A);B = zeros(dim);for i = 1:dim(1) for j = 1:dim(2) % 抽取一块局部区域，这与值域核的大小相对应 iMin = max(i-w,1); iMax = min(i+w,dim(1)); jMin = max(j-w,1); jMax = min(j+w,dim(2)); I = A(iMin:iMax,jMin:jMax); % 计算值域核，也就是灰度值的权值模板 H = exp(-(I-A(i,j)).^2/(2*sigma_r^2)); % 计算双边滤波响应 F = H.*G((iMin:iMax)-i+w+1,(jMin:jMax)-j+w+1); B(i,j) = sum(F(:).*I(:))/sum(F(:)); endend % 对彩色图像进行双边滤波处理的函数function B = bfltColor(A,w,sigma_d,sigma_r) % 将输入的RGB图像转换到CIE颜色空间中if exist('applycform','file') A = applycform(A,makecform('srgb2lab'));else A = colorspace('Lab<-RGB',A);end[X,Y] = meshgrid(-w:w,-w:w);G = exp(-(X.^2+Y.^2)/(2*sigma_d^2));sigma_r = 100*sigma_r; % 进行滤波处理dim = size(A);B = zeros(dim);for i = 1:dim(1) for j = 1:dim(2) iMin = max(i-w,1); iMax = min(i+w,dim(1)); jMin = max(j-w,1); jMax = min(j+w,dim(2)); I = A(iMin:iMax,jMin:jMax,:); dL = I(:,:,1)-A(i,j,1); da = I(:,:,2)-A(i,j,2); db = I(:,:,3)-A(i,j,3); H = exp(-(dL.^2+da.^2+db.^2)/(2*sigma_r^2)); F = H.*G((iMin:iMax)-i+w+1,(jMin:jMax)-j+w+1); norm_F = sum(F(:)); B(i,j,1) = sum(sum(F.*I(:,:,1)))/norm_F; B(i,j,2) = sum(sum(F.*I(:,:,2)))/norm_F; B(i,j,3) = sum(sum(F.*I(:,:,3)))/norm_F; endend % 将滤波结果转换回RGB色彩空间if exist('applycform','file') B = applycform(B,makecform('lab2srgb'));else B = colorspace('RGB<-Lab',B);end
P108
I = imread('cat.gif');I = double(I)/255;w = 5;sigma = [3 0.1];B = bfilter2(I,w,sigma);
P111
I = imread('cameraman.tif');H = fspecial('unsharp');sharpened = imfilter(I,H,'replicate');subplot(121), imshow(I), title('Original Image')subplot(122), imshow(sharpened); title('Sharpened Image')
P112
I = imread('cameraman.tif');Laplace=[0 -1 0;-1 4 -1; 0 -1 0 ];Data = double(I);LaplaceImage=conv2(Data,Laplace,'same');%上面这句也可以写作下面这种形式，作用是等同的%LaplaceImage=imfilter(Data,Laplace,'conv','same');subplot(1,2,1); imshow(uint8(LaplaceImage)); title('Laplace图像');%原图像与拉普拉斯图像叠加DataLap=imadd(Data,LaplaceImage);subplot(1,2,2),imshow(uint8(DataLap));title('锐化增强后的图像');
P124
I = imread('fruits.jpg');SE = strel('rectangle',[10 10]);I2 = imerode(I, SE);figure(2),imshow(I2)
P128
I = imread('fruits.jpg');SE = strel('rectangle',[10 10]);I3 = imdilate(I, SE);figure(3),imshow(I3)
P133
I = imread('character.jpg');figure, imshow(I);SE = strel('square',3);Ie = imerode(I, SE);I2 = I - Ie; %计算内边界figure(2), imshow(I2);Id = imdilate(I, SE);I3 = Id - I; %计算外边界figure(3), imshow(I3);
P134
I = imread('character.jpg');SE = strel('square',3);Ie = imerode(I, SE);Iee = imerode(Ie, SE);Id = imdilate(I, SE);Idd = imdilate(Id, SE);I1 = Ie - Iee;I2 = Idd - Id;I3 = I1 + I2;figure(3), imshow(I3);
（代码发布未完，请待后续...）
