【OpenCV】音符提取(形態學執行個體)

提取水平線和垂直線

  下圖很好地詮釋了腐蝕膨脹的操作原理。

  自適應閾值

adaptiveThreshold()void cv::adaptiveThreshold  (   InputArray  src,   OutputArray  dst,                                double maxValue,   int adaptiveMethod,                                int thresholdType, int  blockSize,                                  double  C )   說明：src為輸入映像，dst為輸出映像，maxValue是最大灰階值，     adaptiveMethod有ADAPTIVE_THRESH_MEAN_C 、ADAPTIVE_THRESH_GAUSSIAN_C      blockSize為掩模大小，C為從均值或加權平均值中減去的常數值。

  掩模

getStructuringElement()Mat cv::getStructuringElement   (   int     shape,                                    Size    ksize,                                    Point   anchor = Point(-1,-1) )   說明：shape有MORPH_RECT、MORPH_CROSS、MORPH_ELLIPSE。ksize為掩模大小。     anchor為掩模中心，Point(-1,-1)預設中心。

程式碼範例

#include <opencv2/opencv.hpp>using namespace std;using namespace cv;int main(int, char** argv){    Mat src,bw,horizontal, vertical;    char* filename = "../data/src.png";    src = imread(filename, IMREAD_GRAYSCALE);    if (src.empty()) { return -1; }    imshow("src",src);    adaptiveThreshold(~src, bw, 255, CV_ADAPTIVE_THRESH_MEAN_C, THRESH_BINARY, 15, -2);    // 自適應閾值    horizontal = bw.clone();    vertical = bw.clone();    Mat structure_h = getStructuringElement(MORPH_RECT, Size(horizontal.cols / 30, 1));    Mat structure_v = getStructuringElement(MORPH_RECT, Size(1, vertical.rows / 30));    erode(horizontal, horizontal, structure_h, Point(-1, -1));              // Point(-1,-1)預設中心    dilate(horizontal, horizontal, structure_h, Point(-1, -1));    erode(vertical, vertical, structure_v, Point(-1, -1));                  // Point(-1,-1)預設中心    dilate(vertical, vertical, structure_v, Point(-1, -1));    imshow("horizontal", horizontal);                                       // 水平    imshow("vertical", vertical);                                           // 垂直    bitwise_not(vertical, vertical);                                        // 取反    Mat edges;    adaptiveThreshold(vertical, edges, 255, CV_ADAPTIVE_THRESH_MEAN_C, THRESH_BINARY, 3, -2);    Mat kernel = Mat::ones(2, 2, CV_8UC1);    dilate(edges, edges, kernel);    Mat smooth;    vertical.copyTo(smooth);    blur(smooth, smooth, Size(2, 2));                                       // 平滑    smooth.copyTo(vertical, edges);                                         // vertical為輸出，edges為同大小的掩模，                                                                            // 掩模非零部分才被複製    imshow("final", vertical);    waitKey(0);    return 0;}

運行結果