《opencv学习》 之 二值化

 OTSU源码：
 1 #include <opencv2/opencv.hpp>
 2 #include <iostream>
 3 #include <windows.h>
 4 
 5 using namespace cv;
 6 using namespace std;
 7 
 8 int OTSU(Mat& src);
 9 int main(int argc, char**argv)
10 {
11     Mat input_image;
12     input_image = imread("1.jpg");
13 
14     if (input_image.data == NULL) {
15         return -1; cout << "can‘t open image.../";
16     }
17     cvtColor(input_image, input_image, CV_BGR2GRAY);
18     const int thre_num = OTSU(input_image);
19     const int height = input_image.rows;
20     const int width = input_image.cols;
21     for (size_t i = 0; i < height; i++)
22     {
23         for (size_t j = 0; j < width; j++)
24         {
25             input_image.at<uchar>(i, j) = input_image.at<uchar>(i, j) >= thre_num ? 0 : 255;
26         }
27     }
28     imshow("input_image2", input_image);
29     waitKey(0);
30     return 0;
31 }
32 
33 int OTSU(Mat& src)
34 {
35     const int height = src.rows;
36     const int width = src.cols;
37     int nCountPix[256] = { 0 };//数量
38     int nProPix[256] = { 0 };//概率
39                              //------------统计像素点个数------------//
40     for (size_t i = 0; i < height; i++)
41     {
42         for (size_t j = 0; j < width; j++)
43         {
44             nCountPix[src.at<uchar>(i, j)]++;
45         }
46     }
47     //-------统计每个像素个数占得比例------//
48     for (size_t i = 0; i < 256; i++)
49     {
50         nProPix[i] = nCountPix[i] / (height*width);
51     }
52     double var_max = 100;//设置一个参数，作为比较结果
53     int       threashold = 0;
54     for (size_t i = 0; i < height; i++)
55     {
56         //----数量count、概率probility、平均概率average、方差variance----//
57         double c0 = 0, c1 = 0, p0 = 0, p1 = 0, a0 = 0, a1 = 0, var = 0;
58         for (size_t j = 0; j < width; j++)
59         {
60             //----前景和背景的计算
61             if (i < j)//背景
62             {
63                 c0 += nCountPix[j];//总数量
64                 p0 += nCountPix[j] * nProPix[j];//总概率
65             }
66             else//前景
67             {
68                 c1 += nCountPix[j];//总数量
69                 p1 += nCountPix[j] * nProPix[j];//总概率
70             }
71         }
72         a0 = p0 / c0;
73         a1 = p1 / c1;
74         var = static_cast<double>(c0*c1*pow((a0 - a1), 0));
75 
76         if (var > var_max)
77         {
78             var_max = var;
79             threashold = i;
80         }
81     }
82     return threashold;
83 }