Question

我正在尝试开发一个可以处理图像骨架的路径/曲线的代码。我希望在两点之间有一个来自骨架的点矢量。

enter image description here

此代码在添加一些点后结束。我没有找到解决方案。

 #include "opencv2/highgui/highgui.hpp"
 #include "opencv2/imgproc/imgproc.hpp"
 #include "opencv2/imgproc/imgproc_c.h"
 #include <opencv2/legacy/compat.hpp>
 #include <opencv2/core/core.hpp>
 #include <iostream>
 #include <cmath>
 #include <list>
 using namespace cv;
 using namespace std;

  //this method to find the 8-neighbors of a point from image 
 vector<Point> search8Neighbor(cv::Mat mat,Point startPoint)
 {
  vector<Point> segment;
  Point p;
    //uchar p1 = mat.at<uchar>(startPoint.x, startPoint.y);
    uchar p2 = mat.at<uchar>(startPoint.x-1, startPoint.y);
    uchar p3 = mat.at<uchar>(startPoint.x-1, startPoint.y+1);
    uchar p4 = mat.at<uchar>(startPoint.x, startPoint.y+1);
    uchar p5 = mat.at<uchar>(startPoint.x+1, startPoint.y+1);
    uchar p6 = mat.at<uchar>(startPoint.x+1, startPoint.y);
    uchar p7 = mat.at<uchar>(startPoint.x+1, startPoint.y-1);
    uchar p8 = mat.at<uchar>(startPoint.x, startPoint.y-1);
    uchar p9 = mat.at<uchar>(startPoint.x-1, startPoint.y-1);

    //if(p1==255) segment.push_back(startPoint.x, startPoint.y);
    if (p2 == 255) {
            p.x=startPoint.x-1;
            p.y=startPoint.y;
            segment.push_back(p);
    }
    if(p3==255) {
            p.x=startPoint.x-1;
            p.y=startPoint.y+1;
            segment.push_back(p);
    }

    if(p4==255) {
            p.x=startPoint.x;
            p.y=startPoint.y+1;
            segment.push_back(p);
    }

    if(p5==255) {
            p.x=startPoint.x+1;
            p.y=startPoint.y+1;
            segment.push_back(p);
    }

    if(p6==255) {
            p.x=startPoint.x+1;
            p.y=startPoint.y;
            segment.push_back(p);
    }
    if(p7==255) {
            p.x=startPoint.x+1;
            p.y=startPoint.y-1;
            segment.push_back(p);
    }
    if(p8==255){
            p.x=startPoint.x;
            p.y=startPoint.y-1;
            segment.push_back(p);
    }

    if(p9==255) {
            p.x=startPoint.x-1;
            p.y=startPoint.y-1;
            segment.push_back(p);
    }

    return segment ;

 }
  //this method return a vector of points from a skeleton that contains all the points 
 //  between a start point "peak" and an end point 
 //this method use the idea of Breadth first search 
  vector<Point> traceLine(Mat img , Point peak)
{
    vector<Point> vect1;
    vector<Point> vect2;
    img.at<uchar>(peak.x,peak.y)=0;//
    vect1.push_back(peak);//add peak to vect1
    while(vect1.size() != 0)
        {
        Point p=vect1[0];
        vect1.erase(vect1.begin());
        vect2.push_back(p);
        vector<Point> vectN;
        vectN=search8Neighbor(img,p);
        vector<Point>::iterator it;
        it = vect1.begin();
        //cout<<vectN.size()<<endl;
        for(int i=0;i<vectN.size();i++)
            {
                 img.at<uchar>(vectN[i].x,vectN[i].y)=0;
                vect1.insert(it,vectN[i]);

            }
        }
return vect2;
}

int main( int argc, char** argv )
{
cv::Mat im = cv::imread("aa.jpg",0);
if (im.empty())
return -1;
 cv::Mat img;
cv::threshold(im, img, 155, 255, CV_THRESH_BINARY);
vector<Point> vect1;
Point p;
p.x=20;
p.y=30;
if(mat.at<uchar>(p.x-1, p.y)==255)
vect1=traceLine(img,p);
imshow("image",im);
cv::waitKey();
return 0 ;
}

Answer 1

Mat以正常的行/列方式为矩阵编制索引，因此您需要mat.at<uchar>(y, x)，而不是mat.at<uchar>(x, y)，否则会产生混淆。

你在哪里：

vector<Point>::iterator it;
it = vect1.begin();
...
for(...)
    vect1.insert(it,vectN[i]);

如果插入导致缓冲区被重新分配，这将会中断，因为它会指向已经解除分配的某个内存，或者可能重新分配给其他内存。而是使用

 vect1.insert(vect1.begin(),vectN[i]);

（这会使程序的行为略有不同）或使用push_back()实际获得广度优先行为。

最大的问题是search8Neighbor（）。如果你有uchar p2 = mat.at<uchar>(startPoint.x-1, startPoint.y);，如果startPoint引用图像边缘的像素，会发生什么？您将引用图像外部的像素，程序将漫游，直到发生异常。在这里，您需要检查图像中的位置，并确保不包含附近图像外部的像素。

修改如果像我说的那样改变，我不相信代码不会起作用。我已经实现了修复，它可以工作：

#include "opencv2/highgui/highgui.hpp" #include "opencv2/imgproc/imgproc.hpp" #include "opencv2/imgproc/imgproc_c.h" #include <opencv2/legacy/compat.hpp> #include <opencv2/core/core.hpp> #include <iostream> #include <cmath> #include <list> using namespace cv; using namespace std; // Find the 8-neighbors of a point from image. vector<Point> search8Neighbor(cv::Mat mat,Point startPoint) { vector<Point> neighbors; vector<Point> offsets; offsets.push_back(Point(-1, 0)); // p2 offsets.push_back(Point(-1, 1)); // p3 offsets.push_back(Point( 0, 1)); // p4 offsets.push_back(Point( 1, 1)); // p5 offsets.push_back(Point( 1, 0)); // p6 offsets.push_back(Point( 1, -1)); // p7 offsets.push_back(Point( 0, -1)); // p8 offsets.push_back(Point(-1, -1)); // p9 vector<Point>::iterator it; for(it = offsets.begin(); it < offsets.end(); ++it) { if(!((it->x < 0 && startPoint.x == 0) || (it->y < 0 && startPoint.y == 0) || (it->x > 0 && startPoint.x == mat.cols - 1) || (it->y > 0 && startPoint.y == mat.rows - 1))) { Point p(startPoint + *it); if(mat.at<uchar>(p) == 255) neighbors.push_back(p); } } return neighbors; } //this method return a vector of points from a skeleton that contains all the points // between a start point "peak" and an end point //this method use the idea of Breadth first search vector<Point> traceLine(Mat img , Point peak) { vector<Point> vect1; vector<Point> vect2; img.at<uchar>(peak.y, peak.x)=0;// vect1.push_back(peak);//add peak to vect1 while(vect1.size() != 0) { Point p=vect1[0]; vect1.erase(vect1.begin()); vect2.push_back(p); vector<Point> vectN; vectN = search8Neighbor(img, p); //cout<< " vectN.size()=" << vectN.size()<<endl; for(int i = 0; i < int(vectN.size()); ++i) { img.at<uchar>(vectN[i].y, vectN[i].x)=0; vect1.push_back(vectN[i]); } } return vect2; } int main( int argc, char** argv ) { cv::Mat im = cv::imread("aa.jpg",0); if (im.empty()) return -1; cv::Mat img; cv::threshold(im, img, 155, 255, CV_THRESH_BINARY); imshow("thresholded image",im); vector<Point> vect1; Point p(3, 32); uchar u = img.at<uchar>(p.x, p.y); if(img.at<uchar>(p) == 255) vect1 = traceLine(img, p); Mat output(im.rows, im.cols, CV_8UC3, Scalar(0, 0, 0)); vector<Point>::iterator it; for(it = vect1.begin(); it < vect1.end(); ++it) { Vec3b green(0, 255, 0); output.at<Vec3b>(*it) = green; } imshow("output", output); cv::waitKey(); return 0 ; }

处理曲线/路径骨架二进制图像

1 个答案: