本文系《数字图像处理原理与实践（MATLAB版）》一书之代码系列的Part1（P1~42）。代码运行结果请參见原书配图。

P20

I = imread('lena.jpg');
BW1 = im2bw(I);
BW2 = im2bw(I, 0.3);
BW3 = im2bw(I, 0.6);
figure
subplot(2,2,1),imshow(I);
title('original');
subplot(2,2,2),imshow(BW1);
title('\default');
subplot(2,2,3),imshow(BW2);
title('level = 0.3');
subplot(2,2,4),imshow(BW3);
title('level = 0.6')

P25-1

IMG1 = imread('airplane.jpg');
IMG2 = imread('baboon.jpg');
IMG3 = imread('lena.jpg');
imshow(IMG1)
imshow(IMG2)
imshow(IMG3)

P25-2

% figure
imshow(IMG1)
figure(5)
imshow(IMG2)

P26

figure;
subplot(1,2,1),subimage(IMG1);
title('airplane');
subplot(1,2,2),subimage(IMG2);
title('baboon');

P31

imhist(I)
imhist(I, n)
[counts, x]=imhist(...)

P32

i = imread('theatre.jpg');
g = rgb2gray(i);
figure
subplot(121), imhist(g);
subplot(122), imhist(g, 64);

P33

i = imread('baboon.jpg');
i = rgb2gray(i);
[m,n]=size(i);
[counts1, x]=imhist(i, 32);
subplot(121), stem(x, counts1);
counts2 = counts1/m/n;
subplot(122), stem(x, counts2);

P35

i=imread('theatre.jpg');
[x,y,z]=size(i);

figure
subplot(221), imshow(i);
title('original image')

%提取红色分量
r=i;
%r(:,:,1)=a(:,:,1);
r(:,:,2)=zeros(x,y);
r(:,:,3)=zeros(x,y);
r=uint8(r);
subplot(222),imshow(r);
title('R-component-image')

%提取绿色分量
g=i;
g(:,:,1)=zeros(x,y);
%g(:,:,2)=a(:,:,2);
g(:,:,3)=zeros(x,y);
g=uint8(g);
subplot(223),imshow(g);
title('G-component-image')

%提取蓝色分量
b=i;
b(:,:,1)=zeros(x,y);
b(:,:,2)=zeros(x,y);
%b(:,:,3)=a(:,:,3);
b=uint8(b);
subplot(224),imshow(b);
title('B-component-image')

P38

i=imread('theatre.jpg');
r=i(:,:,1);
g=i(:,:,2);
b=i(:,:,3);
subplot(1,3,1), imhist(r), title('R component');
subplot(1,3,2), imhist(g), title('G component');
subplot(1,3,3), imhist(b), title('B component');

P41

i = imread('theatre.jpg');
i = im2double(rgb2gray(i));
[m,n]=size(i);

%添加对照度
Fa = 1.25; Fb = 0;
O = Fa.*i + Fb/255;
figure(1), subplot(221), imshow(O);
title('Fa = 1.25, Fb = 0, contrast increasing');
figure(2),subplot(221), [H,x]=imhist(O, 64);
stem(x, (H/m/n), '.');
title('Fa = 1.25, Fb = 0, contrast increasing');

%减小对照度
Fa =0.5; Fb = 0;
O = Fa.*i + Fb/255;
figure(1), subplot(222),imshow(O);
title('Fa = 0.5, Fb = 0, contrast decreasing');
figure(2), subplot(222), [H,x] = imhist(O, 64);
stem(x, (H/m/n), '.');
title('Fa = 0.5, Fb = 0, contrast decreasing');

%线性亮度添加
Fa = 0.5; Fb = 50;
O = Fa.*i + Fb/255;
figure(1), subplot(223), imshow(O);
title('Fa = 0.5, Fb = 50, brightness control');
figure(2), subplot(223), [H,x]=imhist(O,64);
stem(x, (H/m/n), '.');
title('Fa = 0.5, Fb = 50, brightness control');

%反相显示
Fa = -1; Fb = 255;
O = Fa.*i + Fb/255;
figure(1), subplot(224), imshow(O);
title('Fa = -1, Fb = 255, reversal processing');
figure(2), subplot(224),[H,x]=imhist(O, 64);
stem(x, (H/m/n), '.');
title('Fa = -1, Fb = 255, reversal processing');

（代码公布未完，请待兴许...）