每天一点matlab——图像二值化，人为设定阈值

for循环判断每一个像素点，找出每个满足条件的像素点

clear all;

close all;

clc;

A = imread('C:\Users\Administrator\Desktop\验证码图片\6.bmp');

A = rgb2gray(A);

[m,n] = size(A);

value = 200; %设定阈值

B = zeros(m,n)+255; %与A等大的全0矩阵，+255就是把所有像素值都设置成白色

for i = 2:m-1

for j = 2:n-1

if A(i,j)<value %用for循环判断每个像素点

B(i,j) = 0; %在对应的B矩阵中，小于设定阈值的变成黑色

end

end

end

imshow(A);

figure;

imshow(B);

imwrite(B,'C:\Users\Administrator\Desktop\验证码图片\7.bmp')