% RGB的分离
R = pepper(:,:,1);
G = pepper(:,:,2);
B = pepper(:,:,3);
subplot(2,2,1);
imshow(pepper);
title("original");
subplot(2,2,2);
imshow(R);
title("R");
subplot(2,2,3);
imshow(G);
title("G");
subplot(2,2,4);
imshow(B);
title("B");
% RGB的合并
subplot(1,1,1);
rgb(:,:,1) = R;
rgb(:,:,2) = G;
rgb(:,:,3) = B;
imshow(rgb);
彩色图转灰度图
% rgb2gray 彩色图转灰度图
pepper_gray = rgb2gray(pepper);
imshow(pepper_gray)
二值化
[row, col] = size(pepper_gray);
for i = 1:row
for j = 1:col
if pepper(i,j) > 128
pepper_gray(i,j) = 1;
else
pepper_gray(i,j) = 0;
end
end
end
figure;
pepper_bw = logical(pepper_gray);
imshow(pepper_bw);
% imbinarize 系统自带的二值化方式
% method -用于二值化图像的方法: 'global'（默认）| 'adaptive'
% 'Sensitivity' -自适应阈值的敏感度因子: 0.50（默认）| [0，1]范围内的数值
% 'ForegroundPolarity' -确定哪些像素被视为前景像素: 'bright'（默认)| 'dark '
% 'bright': 前景比背景亮
% 'dark' : 前景比背景暗
pepper_gray = rgb2gray(pepper);
bw = imbinarize(pepper_gray, "adaptive","ForegroundPolarity","dark","Sensitivity",0.4);
imshow(bw)
二值化的应用：突出文字
I = imread('printedtext.png');
imshow(I);
bw = imbinarize(I,"adaptive","ForegroundPolarity","dark","Sensitivity",0.4);
imshow(bw)
图像处理相关函数
调整图片大小
% imresize 调整图片大小
% I = imresize(pic, scale); scale为缩放倍数
% I = imresize(pic, [row col]); 调整大小为row*col
I = imread("peppers.png");
imshow(I)
J = imresize(I, 0.5);
imshow(J)
K = imresize(I, [200 200]);
imshow(K)
旋转图像
% I = imrotate(pic,angle); angle为旋转的角度
J = imrotate(I, 45);
imshow(J)
图像的加减乘除
% imadd()
两幅图像相加时，要求大小一致
% imsubtract() 矩阵的减法
% immultiply() 矩阵的点乘
% imdivide() 矩阵的点除
I = imread('rice.png');
imshow(I)
J = imread('cameraman.tif');
imshow(J)
K = imadd(I,J);
imshow(K)
