1-72
% 输入若干个数，当输入0时结束输入，求这些数的平均值和他们的和 sum = 0; n =0; val = input('输入数字(输入0就结束):'); while (val ~= 0) sum = sum + val; n = n+1; val = input('输入数字(输入0时就结束):'); end if (n > 0) sum mean = sum/n end
1-73
% break命令 a = 5; b = 8; for i = 1:4 b = b+1; if i > 2 break end a = a + 2 end
1-74
% continue语句 a = 5;b = 8; for i = 1:4 b = b +1; if i < 2 continue end a = a+ 2 end
1-75
% try 语句,提高程序的容错性 try picture = imread('01.jpg','jpg'); filename = '01.jpg'; catch picture = imread('01.bmp','bmp'); filename = '01.bmp'; end filename
1-76
% 先求两个矩阵的乘机，若出错，则自动转去求两矩阵的点乘 A = magic(2); B = [7, 8; 10, 11]; try C = A*B; catch C = A.*B; end C lasterr %显示出错原因
2.X 图形可视化
2-1
% 准备数据 x = 0 : 0.01: 3 *pi; y1 = cos(x); y2 = cos(2*x); % 设置当前绘图区 figure; % 绘图 plot(x, y1, x, y2); % 设置坐标轴和网格线属性 axis([0 8 -2 2]) grid on; % 标注图形 xlabel('x'); ylabel('y'); title('绘图基本步骤'); % 显示图例 legend('cos(x)', 'cos(2*x)')
2-3
% line 函数绘制cos函数图形 x = 0 :0.15 : 1.5*pi; y = cos(x); line(x, y); axis([0 7 -1.5 1.5]); xlabel('x'); ylabel('y');
2-4
% 画同心圆 theta = linspace(0, 3*pi, 50); r = 0.4: 0.24: 1.74; x = 1 + cos(theta)' *r ; y = 2 + sin(theta)' *r ; plot(x, y, 1, 2, '+'); axis([-1 3 0 4]); title('同心圆'); axis equal; xlabel('x'); ylabel('y');
三维绘图
2-34
% plot3 函数绘制一条三维螺旋线 t = 0: pi/50:8 * pi; x = sin(t); y = cos(t); z = t; plot3(x, y, z, 'r'); xlabel('sin(t)'); ylabel('cos(t)'); zlabel('z'); title('绘制三维螺旋线'); legend('t'); grid on;
3.X 图像处理基础
3-1
% imfinfo查询图像文件信息 info = imfinfo('01.jpg'); info
3-2
% 图像文件读取 clc; l1 = imread('01.jpg'); %读取一副RGB图像 %l2 = imread( '02.jpg', ' tif '); %读取一副灰度图像 l3 = imread('F:matlab_test 3.jpg'); figure; subplot(1, 2, 1), imshow(l1); title('显示RGB图像'); %subplot(1, 3, 2), imshow(l2); %title('显示灰度图像'); subplot(1, 2, 2), imshow(l3); title('显示指定路径下的图像文件');
3-3
1 % 内联函数 2 f1 = inline ('x^2 + y^2', 'x', 'y'); 3 f1(2, 3) 4 5 % 匿名函数 6 f2 = @(x, y) x^2 + y^2; 7 f2(3, 4)
1 % 读取 2 x = imread('02.jpg'); 3 % 显示 4 imshow(x); 5 imshow(x, [100 150]); 6 % 分区 7 subplot(2, 2, 1); 8 imshow(x); title('图一'); 9 % 保存 10 imwrite( x, 'xieyi.jpg');
% 图像邻域操作 x = imread('03.jpg'); x = rgb2gray(x); f = @(x) max(x(:)); y = nlfilter(x , [3 3], f); %过滤函数处理灰度图像 subplot(1, 2, 1);imshow(x); subplot(1, 2, 2);imshow(y);
1 % 图像叠加 2 I = imread('01.jpg'); 3 size(I) 4 J = imread('02.jpg'); 5 size(J) 6 W = imadd(J, I, 'uint16');%两幅图相加 7 K = imadd(I, 100);%增加亮度 8 imshow(K);
%快速邻域图像块操作 x = imread('04.jpg'); x = rgb2gray(x); myf = @(x) max(x); y = uint8 (colfilt(x, [3 3], 'sliding', myf)); subplot(1, 2, 1);imshow(x);title('原图'); subplot(1, 2, 2);imshow(y);title('处理后的图');
% 绝对差操作图像 x = imread('04.jpg'); x = rgb2gray(x); myf = @(x) mean(x); y = uint8(colfilt(x, [4 4], 'sliding', myf)); z = imabsdiff(x, y); subplot(3, 1, 1);imshow(x); subplot(3, 1, 2);imshow(y); subplot(3, 1, 3);imshow(z);
1 % 绝对值差函数 2 Z = imabsdiff( A, B); 3 imshow(Z)
1 % 图像的减法 2 x = imread('03.jpg'); 3 x = imadd(x, 100); 4 x = rgb2gray(x); 5 y = imread('0301.jpg'); 6 imshow(y) 7 z = imsubtract(x, y);%减法函数 8 imshow(z);
1 % 图像的乘法 2 x = imread('03.jpg'); 3 x = imadd(x, 100); 4 x = rgb2gray(x); 5 y = imread('0301.jpg'); 6 figure; 7 imshow(y); 8 z = immultiply(x, y);%乘法函数 9 figure; 10 imshow(z); 11 w = immultiply(z, 0.5); 12 figure; 13 imshow(w);
% 求补运算 i = imread('04.jpg'); i = rgb2gray(i); i1 = imcomplement(i) figure;imshow(i); figure;imshow(i1);
1 % 改变图像大小 2 I = imread('01.jpg'); 3 O = imresize(I, 0.5, 'bicubic'); 4 figure; 5 imshow(I); 6 figure; 7 imshow(O);
1 % 图像剪切 2 I = imread('01.jpg'); 3 I2 = imcrop(I , [10 10 100 100] ); 4 imshow(I); 5 figure; 6 imshow(I2);
1 % 图像旋转 2 I = imread('02.jpg'); 3 thetal = 30; 4 J = imrotate(I, thetal); 5 thetal2 = -30; 6 K = imrotate( I, thetal2, 'crop'); 7 figure; 8 imshow(I); 9 figure, imshow(J); 10 figure, imshow(K);
1 % 图像的几何变换 2 I = imread('03.jpg'); 3 imshow(I); 4 I = rgb2gray(I); 5 tform = affine2d ([cosd(30) sind(30) 0; -sind(30) cosd(30) 0; 0 0 1]); %二维仿射函数 6 J = imwarp(I , tform); %图像几何变换 7 figure; 8 imshow(J)
1 % 一维离散傅里叶变换 2 Fs = 1000; 3 T = 1/Fs; 4 L = 1000; 5 t = (0 :L-1) * T; 6 S = 0.7 * sin( 2 * pi * 50 * t) + sin( 2 * pi * 120 * t); 7 X = S + 2 * randn( size(t)); 8 Y = fft(X); 9 P2 = abs(Y); 10 plot(P2(1 : end/2));
1 %快速傅里叶变换 2 f = zeros(256,256); 3 f (30: 144 , 78:102) = 1; 4 imshow(f); 5 F = fft2(f); 6 F2 = log(abs(F)); 7 figure, imshow(F2, [-1, 5]);
1 % 计算连个矩阵的卷积 2 A = [ 1 2 3; 4 5 6; 7 8 9]; 3 B = ones(3); 4 % 扩展矩阵维数 5 A(8, 8) = 0; 6 B(8, 8) = 0; 7 %对A，B进行傅里叶变换并乘积后进行逆变换 8 C = ifft ( fft2(A) .* fft2(B)); 9 % 取有效数据 10 C = C(1:5, 1:5); 11 C = real(C);
1 % 离散余弦变换，常用于图像压缩 2 I = imread('03.jpg'); 3 I = rgb2gray(I); 4 imshow(I); 5 % 离散余弦变换 6 J = dct2(I); 7 figure;imshow(log(abs(J)), []);
% 图像重构 RGB = imread('04.jpg'); I = rgb2gray(RGB); imshow(I); J = dct2(I); J(abs(J) < 10) = 0; K = idct2(J); figure; imshow(K, [0, 255]);