Python OpenCVは文字の後の雑線を取り除いて操作します。

  src = cv2.imread("28.png")
  gray_src = cv2.cvtColor(src, cv2.COLOR_BGR2GRAY)
  #cv2.imshow("input image", src)
  #cv2.imshow("gray image", gray_src)
  #cv2.waitKey(0)
  gray_src = cv2.bitwise_not(gray_src)
  #   
  binary_src = cv2.adaptiveThreshold(gray_src, 255, cv2.ADAPTIVE_THRESH_MEAN_C, cv2.THRESH_BINARY, 15, -2)
  cv2.namedWindow("result image", cv2.WINDOW_AUTOSIZE)
  cv2.imshow("result image", binary_src)
  #cv2.waitKey(0)
  #        src.shape[1]  src  
  #hline = cv2.getStructuringElement(cv2.MORPH_RECT, (1, 1), (-1, -1))
  hline = cv2.getStructuringElement(cv2.MORPH_RECT, (1, 4), (-1, -1)) #      ，   
  #        src.shape[0]  src  
  vline = cv2.getStructuringElement(cv2.MORPH_RECT, (4, 1), (-1, -1))
  #vline = cv2.getStructuringElement(cv2.MORPH_RECT, (3, 3))
  #             ――      
  #temp = cv2.erode(binary_src, hline)   #  
  #dst = cv2.dilate(temp, hline)      #  
  #    
  dst = cv2.morphologyEx(binary_src, cv2.MORPH_OPEN, hline)  #    
  dst = cv2.morphologyEx(dst, cv2.MORPH_OPEN, vline)  #    
  #                ，     。    
  dst = cv2.bitwise_not(dst)
  cv2.imshow("Final image", dst)
  cv2.waitKey(0)

#include<opencv2\opencv.hpp>
#include<iostream>
 
using namespace std;
using namespace cv;
 
int main(int argc, char* argv[])
{
	Mat src = imread("  3.jpg");
	if (src.empty())
	{
		return -1;
	}
	String strInput = "input image";
	namedWindow(strInput, CV_WINDOW_AUTOSIZE);
	imshow(strInput, src);
	Mat dst;
	cvtColor(src, dst, CV_BGR2GRAY);//   
	imshow("output grap image", dst);
	Mat binimg;
	adaptiveThreshold(~dst, binimg, 255, ADAPTIVE_THRESH_MEAN_C, ADAPTIVE_THRESH_MEAN_C, 15, -2);//   
	imshow("binary image", binimg);
	Mat hLine = getStructuringElement(MORPH_RECT, Size(src.cols/16, 1), Point(-1, -1));//    
	Mat vLine = getStructuringElement(MORPH_RECT, Size(1, src.rows / 16), Point(-1, -1));//    
 
	Mat kernel = getStructuringElement(MORPH_RECT, Size(3, 3), Point(-1, -1));//         
	Mat tmp;
	//erode(binimg, tmp, vLine);
	//dilate(tmp, dst, vLine);
	morphologyEx(binimg, dst, CV_MOP_OPEN,hLine);
	bitwise_not(dst, dst);//  
	blur(dst, dst, Size(3, 3), Point(-1, -1));
	imshow("Final image", dst);
 
	waitKey(0);
	return 0;
}