├── deploy.sh
├── skeleton.h
├── images
    ├── concept.jpg
    ├── concept1.jpg
    ├── result0.jpg
    └── result50.jpg
├── main.cpp
├── README.md
└── thin.h


/deploy.sh:
--------------------------------------------------------------------------------
1 | git add .
2 | git commit -m "update"
3 | git push -f origin master


--------------------------------------------------------------------------------
/skeleton.h:
--------------------------------------------------------------------------------
https://raw.githubusercontent.com/GEO-LIKE/SkeletonExtraction/HEAD/skeleton.h


--------------------------------------------------------------------------------
/images/concept.jpg:
--------------------------------------------------------------------------------
https://raw.githubusercontent.com/GEO-LIKE/SkeletonExtraction/HEAD/images/concept.jpg


--------------------------------------------------------------------------------
/images/concept1.jpg:
--------------------------------------------------------------------------------
https://raw.githubusercontent.com/GEO-LIKE/SkeletonExtraction/HEAD/images/concept1.jpg


--------------------------------------------------------------------------------
/images/result0.jpg:
--------------------------------------------------------------------------------
https://raw.githubusercontent.com/GEO-LIKE/SkeletonExtraction/HEAD/images/result0.jpg


--------------------------------------------------------------------------------
/images/result50.jpg:
--------------------------------------------------------------------------------
https://raw.githubusercontent.com/GEO-LIKE/SkeletonExtraction/HEAD/images/result50.jpg


--------------------------------------------------------------------------------
/main.cpp:
--------------------------------------------------------------------------------
 1 | #include <opencv2\opencv.hpp>
 2 | #include "skeleton.h"
 3 | #include "thin.h"
 4 | 
 5 | int main() {
 6 | 	// Create a matrix and initialization
 7 | 	cv::Mat src = GenerateMat();
 8 | 	cv::Mat grayImage, binaryImage, distImage, gradientImage,ridge;
 9 | 	cv::cvtColor(src, grayImage,CV_BGR2GRAY);
10 | 	// Binarization
11 | 	cv::threshold(grayImage, binaryImage,150, 255, cv::THRESH_BINARY);
12 | 	// Thinning
13 | 	thinning(binaryImage, ridge);
14 | 
15 | 	cv::imshow("Skeleton", ridge);
16 | 	cv::imwrite("Skeleton.jpg", ridge);
17 | 	cv::waitKey(0);
18 | 	cv::destroyAllWindows();
19 | 
20 | 	return(0);
21 | }
22 | 


--------------------------------------------------------------------------------
/README.md:
--------------------------------------------------------------------------------
 1 | # SkeletonExtraction
 2 | Extract the skeleton of an binary image
 3 | 
 4 | ### Environment configuration
 5 | - vs2015
 6 | - openCV 3.4.1
 7 | 
 8 | ### Basic concepts
 9 | 
10 | ![Structure Element B](https://github.com/GEO-LIKE/SkeletonExtraction/raw/master/images/concept1.jpg)
11 | 
12 | Sequential thinning by use structuring element L
13 | 
14 | ![Structure Element L](https://github.com/GEO-LIKE/SkeletonExtraction/raw/master/images/concept.jpg)
15 | 
16 | ### Utilizing <code>GenerateMat</code> to produce the following image：
17 | 
18 | ![Initial Shapes](https://github.com/GEO-LIKE/SkeletonExtraction/raw/master/images/result0.jpg)
19 | 
20 | ### Extract skeleton by <code>thinning</code>：
21 | 
22 | ![Skeleton](https://github.com/GEO-LIKE/SkeletonExtraction/raw/master/images/result50.jpg)
23 | 
24 | #### Reference
25 | [1] Image Processing, Analysis, and Machine Vision, Fourth Edition, Milan Sonka, Vaclav Hlavac, Roger Boyle, CENGAGE Learning.
26 | 
27 | [2] Digital Image Processing, Third Edition, Rafael C. Gonzalez, Richard E. Woods, Pearson.


--------------------------------------------------------------------------------
/thin.h:
--------------------------------------------------------------------------------
  1 | #ifndef THIN
  2 | #define THIN
  3 | 
  4 | #include<opencv2/opencv.hpp>
  5 | #include<string>
  6 | #include <windows.h>
  7 | //define patterns
  8 | //patterns defined in "Image Processing, Analysis, and Machine Vision Fourth Edition, Milan Sonka et. al."
  9 | const int L1[3][3] = {
 10 | 	{0,0,0},
 11 | 	{2,1,2},
 12 | 	{1,1,1} };
 13 | const int L2[3][3] = {
 14 | 	{ 1,2,0 },
 15 | 	{ 1,1,0 },
 16 | 	{ 1,2,0 } };
 17 | const int L3[3][3] = {
 18 | 	{ 1,1,1 },
 19 | 	{ 2,1,2 },
 20 | 	{ 0,0,0 } };
 21 | const int L4[3][3] = {
 22 | 	{ 0,2,1 },
 23 | 	{ 0,1,1 },
 24 | 	{ 0,2,1 } };
 25 | /*
 26 | const int L5[3][3] = {
 27 | 	{ 2,0,0 },
 28 | 	{ 1,1,0 },
 29 | 	{ 2,1,2 } };
 30 | const int L6[3][3] = {
 31 | 	{ 2,1,2 },
 32 | 	{ 1,1,0 },
 33 | 	{ 2,0,0 } };
 34 | const int L7[3][3] = {
 35 | 	{ 2,1,2 },
 36 | 	{ 0,1,1 },
 37 | 	{ 0,0,2 } };
 38 | const int L8[3][3] = {
 39 | 	{ 0,0,2 },
 40 | 	{ 0,1,1 },
 41 | 	{ 2,1,2 } };*/
 42 | auto L_Set = { L1,L2,L3,L4 };// , L5, L6, L7, L8 };
 43 | //
 44 | //bool dirExists(const std::string& dirName_in)
 45 | //{
 46 | //	DWORD ftyp = GetFileAttributesA(dirName_in.c_str());
 47 | //	if (ftyp == INVALID_FILE_ATTRIBUTES)
 48 | //		return false;  //something is wrong with your path!
 49 | //
 50 | //	if (ftyp & FILE_ATTRIBUTE_DIRECTORY)
 51 | //		return true;   // this is a directory!
 52 | //
 53 | //	return false;    // this is not a directory!
 54 | //}
 55 | 
 56 | void createFolder(std::string dirName) {
 57 | 	std::string commandMd = "mkdir " + dirName;
 58 | 	std::string commandRd = "rmdir /s /q " + dirName;
 59 | 	if (std::system(commandMd.c_str()))
 60 | 	{
 61 | 		std::cout << "remove dir:output, and re-makedir" << std::endl;
 62 | 		std::system(commandRd.c_str());
 63 | 	}
 64 | 	std::system(commandMd.c_str());
 65 | }
 66 | 
 67 | bool compare(cv::Mat& src, const int pattern[][3]) {
 68 | 	bool flag = false;
 69 | 	for (int i = 0; i < 3; i++) {
 70 | 		for (int j = 0; j < 3; j++) {
 71 | 			if (!src.at<uchar>(i, j) && pattern[i][j] == 1) {
 72 | 				flag = false;
 73 | 				return flag;
 74 | 			}else if (src.at<uchar>(i, j) && pattern[i][j] == 0) {
 75 | 				flag = false;
 76 | 				return flag;
 77 | 			}else
 78 | 				flag = true;
 79 | 		}
 80 | 	}
 81 | 	return flag;
 82 | }
 83 | void findContour(cv::Mat& src, std::vector<cv::Point>& outlines) {
 84 | 	//std::string dirName = "./output_Contours";
 85 | 	//createFolder(dirName);
 86 | 	cv::Mat temp = src.clone();
 87 | 	const int B[][3] = { {1,1,1},{1,1,1},{1,1,1} };
 88 | 	for (int i = 1; i < src.rows-1; i++) {
 89 | 		for (int j = 1; j < src.cols-1; j++) {
 90 | 			cv::Mat roi = src(cv::Range(i - 1, i + 2), cv::Range(j - 1, j + 2));
 91 | 			if (compare(roi, B))
 92 | 				temp.at<uchar>(i, j) = 0;
 93 | 		}
 94 | 	}
 95 | 	for (int i = 1; i < src.rows - 1; i++) {
 96 | 		for (int j = 1; j < src.cols - 1; j++) {
 97 | 			if (temp.at<uchar>(i,j))
 98 | 			outlines.push_back(cv::Point2i(i, j));
 99 | 		}
100 | 	}
101 | 	//cv::imwrite(dirName+"/outlines.jpg", temp);
102 | }
103 | bool thinning_it(cv::Mat& src,cv::Mat& ridge) {
104 | 	ridge = src.clone();
105 | 	int flag = false;
106 | 	for (auto pattern : L_Set) {
107 | 		if (flag)
108 | 			return flag;
109 | 		else	
110 | 			flag = true;
111 | 
112 | 		std::vector<cv::Point2i> outlines;
113 | 		findContour(src, outlines);
114 | 		if (outlines.empty())
115 | 		{
116 | 			std::cout << "No skeleton" << std::endl;
117 | 			return true;
118 | 		}
119 | 		for (cv::Point2i point : outlines) {
120 | 			int i = point.x;
121 | 			int j = point.y;
122 | 			cv::Mat roi = src(cv::Range(i - 1, i + 2), cv::Range(j - 1, j + 2));
123 | 			if (src.at<uchar>(i, j) && compare(roi, pattern))
124 | 			{
125 | 				ridge.at<uchar>(i, j) = 0;
126 | 				flag = false;
127 | 			}
128 | 
129 | 		}
130 | 	}
131 | 	return flag;
132 | }
133 | 
134 | void thinning(cv::Mat& src, cv::Mat& ridge) {
135 | 	std::string dirName = "output";
136 | 	createFolder(dirName);
137 | 	int i = 0;
138 | 	bool flag = false;
139 | 	ridge = src.clone();
140 | 	do{
141 | 		flag = thinning_it(ridge.clone(), ridge);
142 | 		std::cout << i << std::endl;
143 | 		 std::string name = dirName+"/result"+ std::to_string(i++)+".jpg";
144 | 		cv::imwrite(name, ridge);
145 | 	} while (!flag);
146 | 	
147 | }
148 | 
149 | 
150 | #endif // !THIN
151 | 
152 | 


--------------------------------------------------------------------------------