Opencv3 C++ VS2017 学习笔记 09形态学操作应用

• adaptiveThreshold(~gray, bin, 255,    ADAPTIVE_THRESH_MEAN_C, THRESH_BINARY, 15,-2);
  • 自适应阈值化操作,这里只用二值化
  • 注意gray要取反,这里要参考我们的背景颜色, 我用的是白色背景,所以要取反这样二值图片就是黑色背景
  • 参数:原图,输出图,二值化算法,阈值类型(不必纠结), 操作块大小(adaptiveThreshold的计算单位是像素的邻域块，邻域块取多大，就由这个值作决定),偏移值调整量(±和0都可以)
  • 15是邻域块大小,发现自适应二值化得到的不理想时可调整它和偏移量-2
• 保留水平线
  • adaptiveThreshold(~gray, bin, 255,    ADAPTIVE_THRESH_MEAN_C, THRESH_BINARY, 3,-2);
  • Mat hline = getStructuringElement(MORPH_RECT, Size(src0.cols / 15, 1), Point(-1, -1));
  • 
• 保留垂直线
  • adaptiveThreshold(~gray, bin, 255,    ADAPTIVE_THRESH_MEAN_C, THRESH_BINARY, 3,-2);
  • Mat vline = getStructuringElement(MORPH_RECT, Size(1, src0.rows/15), Point(-1, -1));
  • 
• 保留字母
  • adaptiveThreshold(~gray, bin, 255,    ADAPTIVE_THRESH_MEAN_C, THRESH_BINARY, 13,-2);
  • Mat kernel = getStructuringElement(MORPH_RECT, Size(4,4), Point(-1, -1));
  • 

#include "pch.h"
#include <iostream>
#include <opencv2/opencv.hpp>
#include <string>

using namespace std;
using namespace cv;

Mat src0, gray, bin, dst;
int main(int argc, char ** argv)
{
	src0 = imread("C:\\Users\\xujin\\Desktop\\ABCD.PNG");
	if (!src0.data)
	{
		cout << "no image";
		return -1;
	}
	namedWindow("src0_image", WINDOW_AUTOSIZE);
	imshow("src0_image", src0);
	cvtColor(src0, gray, COLOR_BGR2GRAY);
	namedWindow("gray_image", WINDOW_AUTOSIZE);
	namedWindow("bin_image", WINDOW_AUTOSIZE);
	imshow("gray_image", gray);

	//二值化
	adaptiveThreshold(~gray, bin, 255,	ADAPTIVE_THRESH_MEAN_C, THRESH_BINARY, 13,-2);
	//注意gray要取反,这里要参考我们的背景颜色, 我用的是白色背景,所以要取反这样二值图片就是黑色背景
	imshow("bin_image", bin);
	//保留水平线
	Mat hline = getStructuringElement(MORPH_RECT, Size(src0.cols / 15, 1), Point(-1, -1));
	//保留垂直线
	Mat vline = getStructuringElement(MORPH_RECT, Size(1, src0.rows/15), Point(-1, -1));
	//保留字母
	Mat kernel = getStructuringElement(MORPH_RECT, Size(3,3), Point(-1, -1));
	//这里主要是靠kernel的size来抹除细小噪声, 因为噪点比字母要小很多,所以可以靠小的kernel进行抹除

	Mat temp;
	erode(bin, temp, kernel, Point(-1, -1));
	dilate(temp, dst, kernel, Point(-1, -1));

	//erode(bin, temp, vline, Point(-1, -1));
	//dilate(temp, dst, vline, Point(-1, -1));

	namedWindow("dst_image", WINDOW_AUTOSIZE);
	imshow("dst_image", dst);
	waitKey(0);
	return 0;
}