OpenCV——字符提取并保存

截取图中上方数码管中的数字

基本思路：

1、将图像转化为灰度图

2、截取ROI区域

3、二值化

4、循环遍历每一行和每一列，得到字符的坐标

5、截取并保存

 #include <opencv2/opencv.hpp>
 #include <iostream>
 #include <math.h>
 #include <stdio.h>

 using namespace cv;
 using namespace std;

 int getColSum(Mat& src, int t);
 int getRowSum(Mat& src, int t);
 void cutLeft(Mat& src, Mat& leftImg, Mat& rightImg);
 void cutTop(Mat& src, Mat& dstImg);

 int main()
 {
     Mat src = imread("数字.jpg", );
     threshold(src, src, , , THRESH_BINARY|THRESH_OTSU);
     imshow("origin", src);

     Mat roi = src(Rect(, , src.cols-, ));//截取ROI区域
     imshow("ROI", roi);
     //形态学操作去除干扰
     Mat kernel = getStructuringElement(MORPH_RECT, Size(, ), Point(-, -));
     morphologyEx(roi, roi, MORPH_OPEN, kernel);

     Mat kernel2 = getStructuringElement(MORPH_RECT, Size(,), Point(-, -));
     dilate(roi, roi, kernel2);
     imshow("ROI", roi);

     Mat leftImg, rightImg;

     rightImg = roi.clone();
     string nameLeft[] = {"digital_1.jpg","digital_2.jpg" ,"digital_3.jpg" ,"digital_4.jpg" ,"digital_5.jpg" };
     for (int i = ; i < ; i++) {

         cutLeft(rightImg, leftImg, rightImg);
         imwrite(nameLeft[i], leftImg);//保存
     }

     waitKey();
     return ;
 }
 //函数作用：计算某一列的像素和
 //输入为二值图像
 int getColSum(Mat& src, int t) {
     int rowNumber = src.rows;//行数
     int colNumber = src.cols;//列数
     uchar ColSum = ;
     for (int i = ; i < rowNumber; i++)
     {
         for (int j = ; j < colNumber; j++)
         {
             if (j == t)
             {

                 ColSum += src.at<uchar>(i, j);
             }

         }
     }
     return ColSum;
 }

 int getRowSum(Mat& src, int t) {
     int rowNumber = src.rows;//行数
     int colNumber = src.cols;//列数
     uchar RowSum = ;
     for (int i = ; i < rowNumber; i++)
     {
         if (i== t)
         {

             for (int j = ; j < colNumber; j++)
             {

                 RowSum += src.at<uchar>(i, j);

             }
         }
     }
     return RowSum;
 }
 void cutLeft(Mat& src, Mat& leftImg, Mat& rightImg)//左右切割
 {
     int left, right;
     left = ;
     right = src.cols;

     //循环遍历每一列，记录下左端的坐标
     int i;
     for (i = ; i < src.cols; i++)
     {
         int colValue = getColSum(src, i);
         //cout <<i<<" th "<< colValue << endl;
         if (colValue > )
         {
             left = i;
             break;
         }
     }    

     //接着循环遍历每一列，记录下右端的坐标
     for (; i < src.cols; i++)
     {
         int colValue = getColSum(src, i);
         //cout << i << " th " << colValue << endl;
         if (colValue == )
         {
             right = i;
             break;
         }
     }

     int width = right - left;//计算字符的宽度

     Rect rect(left, , width, src.rows);
     leftImg = src(rect);
     Rect rectRight(right, , src.cols - right, src.rows);
     rightImg = src(rectRight);
     cutTop(leftImg, leftImg);

 }

 void cutTop(Mat& src, Mat& dstImg)//上下切割
 {
     int top, bottom;
     top = ;
     bottom = src.rows;

     int i;
     for (i = ; i < src.rows; i++)
     {
         int colValue = getRowSum(src, i);
         //cout <<i<<" th "<< colValue << endl;
         if (colValue > )
         {
             top = i;
             break;
         }
     }
     for (; i < src.rows; i++)
     {
         int colValue = getRowSum(src, i);
         //cout << i << " th " << colValue << endl;
         if (colValue == )
         {
             bottom = i;
             break;
         }
     }

     int height = bottom - top;
     Rect rect(, top, src.cols, height);
     dstImg = src(rect);
 }