截字符

1.思路

预处理----->边缘检测----->画框

1.预处理

滤波，形态学开、闭操作，膨胀，腐蚀

medianBlur(result, result, 5);

        Mat mask,canny;

        Mat kernel = getStructuringElement(MORPH_RECT, Size(5, 5));

        morphologyEx(result, mask, MORPH_GRADIENT, kernel);//形态学梯度

        Canny(mask, canny, 100, 120);

        Mat element = getStructuringElement(MORPH_ELLIPSE, Size(5, 5));

        dilate(canny, kernel, element);//膨胀//预处理

        Canny(kernel, canny, 100, 120);
        bitwise_not(canny,canny);
        erode(canny, canny, element);//腐蚀

2.边缘检测canny

效果：

3.画框

for (size_t i = 0; i < contours.size(); ++i) {

            Rect rect = boundingRect(contours[i]);

            double area = contourArea(contours[i]);

                 if (area>200&&area<1000) {

                    rectangle(result, rect, Scalar(0, 255, 0), 2);
                 }
        }

效果：

2.代码

#include <iostream>

#include <opencv2/opencv.hpp>

using namespace std;

using namespace cv;

void Clear_MicroConnected_Areas(cv::Mat src, cv::Mat &dst, double min_area);

Mat IdentifyLeaves(cv::Mat input);

vector<Mat> read_images_in_folder(cv::String pattern);

int main()

{

    cv::String pattern = "D:/photo/books/*.jpg"; // the pattern to match the image file names

      vector<cv::String> fn;

      glob(pattern, fn, false);

      for (size_t i = 0; i < fn.size(); i++)

      {

          Mat src = imread(fn[i]); // read the image

          if (src.empty()) // check if the image is successfully loaded

          {

              cout << "Could not read the image: " << fn[i] << endl;

              continue;

          }

         Mat result = IdentifyLeaves(src);

        medianBlur(result, result, 5);

        Mat mask,canny;

        Mat kernel = getStructuringElement(MORPH_RECT, Size(5, 5));

        morphologyEx(result, mask, MORPH_GRADIENT, kernel);//形态学梯度

        Canny(mask, canny, 100, 120);

        Mat element = getStructuringElement(MORPH_ELLIPSE, Size(5, 5));

        dilate(canny, kernel, element);//膨胀//预处理

        Canny(kernel, canny, 100, 120);

        bitwise_not(canny,canny);

        erode(canny, canny, element);//腐蚀

        vector<vector<Point>> contours;

        findContours(canny, contours, RETR_CCOMP, CHAIN_APPROX_NONE);

        // Draw bounding boxes around the contours

        for (size_t i = 0; i < contours.size(); ++i) {

            Rect rect = boundingRect(contours[i]);

            double area = contourArea(contours[i]);

                 if (area>200&&area<1000) {

                    rectangle(result, rect, Scalar(0, 255, 0), 2);

                 }

        }

    namedWindow("result", WINDOW_KEEPRATIO);

    imshow("result", result);

    namedWindow("1", WINDOW_KEEPRATIO);

    imshow("1", canny);

    waitKey(0);

      }

    return 0;

}

void Clear_MicroConnected_Areas(cv::Mat src, cv::Mat &dst, double min_area)

{

    // 备份复制

    dst = src.clone();

    std::vector<std::vector<cv::Point> > contours;  // 创建轮廓容器

    std::vector<cv::Vec4i>  hierarchy;

    // 寻找轮廓的函数

    cv::findContours(src, contours, hierarchy, cv::RETR_TREE, cv::CHAIN_APPROX_NONE, cv::Point());

    if (!contours.empty() && !hierarchy.empty())

    {

        std::vector<std::vector<cv::Point> >::const_iterator itc = contours.begin();

        // 遍历所有轮廓

        while (itc != contours.end())

        {

            // 定位当前轮廓所在位置

            cv::Rect rect = cv::boundingRect(cv::Mat(*itc));

            // contourArea函数计算连通区面积

            double area = contourArea(*itc);

            // 若面积小于设置的阈值

            if (area < min_area)

            {

                // 遍历轮廓所在位置所有像素点

                for (int i = rect.y; i < rect.y + rect.height; i++)

                {

                    uchar *output_data = dst.ptr<uchar>(i);

                    for (int j = rect.x; j < rect.x + rect.width; j++)

                    {

                        // 将连通区的值置0

                        if (output_data[j] == 255)

                        {

                            output_data[j] = 0;

                        }

                    }

                }

            }

            itc++;

        }

    }

}

Mat IdentifyLeaves(cv::Mat input)

{

    CV_Assert(input.channels() == 3);

    Mat temp, result, mask, hole;

    int row = input.rows;

    int col = input.cols;

    // 高斯滤波

    GaussianBlur(input, temp, Size(5, 5), 0);

    // 通道拆分

    vector<cv::Mat> c;

    split(temp, c);

    // 绿通道-蓝通道，提取绿色区域

    Mat diff = c[1] - c[2];

    threshold(diff, mask, 0, 255, THRESH_OTSU);

    // 闭运算封口

    cv::Mat element = getStructuringElement(MORPH_ELLIPSE, Size(9, 9));

    cv::morphologyEx(mask, mask, MORPH_CLOSE, element);

    // 孔洞闭合

    hole = 255 - mask;

    Clear_MicroConnected_Areas(hole, hole, row*col / 300);

    mask = 255 - hole;

    Clear_MicroConnected_Areas(mask, mask, row*col / 300);//除噪点

    // 识别区域标记

    result = input.clone();

    result.setTo(Scalar(0, 0, 0), mask == 0);

    return result;

}