Esqueletizar una imagen binaria

Implementación del algoritmo de Zhang Suen y Guo Hall.

Author: devcarmelo

opencv-esqueleto/CMakeLists.txt

@@ -0,0 +1,10 @@
+cmake_minimum_required(VERSION 3.0)
+
+project( Tutorial_OpenCV_Esqueleto )
+
+find_package( OpenCV 3.0.0 REQUIRED )
+
+file(COPY star.jpg DESTINATION data)
+
+add_executable( ${PROJECT_NAME} source.cpp)
+target_link_libraries( ${PROJECT_NAME} ${OpenCV_LIBS} )

opencv-esqueleto/source.cpp

@@ -0,0 +1,133 @@
+#include <iostream>
+#include <opencv2/opencv.hpp>
+
+using namespace cv;
+using namespace std;
+
+#define THINNING_ZHANGSUEN 1
+#define THINNING_GUOHALL 2
+
+// Applies a thinning iteration to a binary image
+static void thinningIteration(Mat img, int iter, int thinningType) {
+	Mat marker = Mat::zeros(img.size(), CV_8UC1);
+
+	if (thinningType == THINNING_ZHANGSUEN) {
+		for (int i = 1; i < img.rows - 1; i++)
+		{
+			for (int j = 1; j < img.cols - 1; j++)
+			{
+				uchar p2 = img.at<uchar>(i - 1, j);
+				uchar p3 = img.at<uchar>(i - 1, j + 1);
+				uchar p4 = img.at<uchar>(i, j + 1);
+				uchar p5 = img.at<uchar>(i + 1, j + 1);
+				uchar p6 = img.at<uchar>(i + 1, j);
+				uchar p7 = img.at<uchar>(i + 1, j - 1);
+				uchar p8 = img.at<uchar>(i, j - 1);
+				uchar p9 = img.at<uchar>(i - 1, j - 1);
+
+				int A = (p2 == 0 && p3 == 1) + (p3 == 0 && p4 == 1) +
+					(p4 == 0 && p5 == 1) + (p5 == 0 && p6 == 1) +
+					(p6 == 0 && p7 == 1) + (p7 == 0 && p8 == 1) +
+					(p8 == 0 && p9 == 1) + (p9 == 0 && p2 == 1);
+				int B = p2 + p3 + p4 + p5 + p6 + p7 + p8 + p9;
+				int m1 = iter == 0 ? (p2 * p4 * p6) : (p2 * p4 * p8);
+				int m2 = iter == 0 ? (p4 * p6 * p8) : (p2 * p6 * p8);
+
+				if (A == 1 && (B >= 2 && B <= 6) && m1 == 0 && m2 == 0)
+					marker.at<uchar>(i, j) = 1;
+			}
+		}
+	}
+
+	if (thinningType == THINNING_GUOHALL) {
+		for (int i = 1; i < img.rows - 1; i++)
+		{
+			for (int j = 1; j < img.cols - 1; j++)
+			{
+				uchar p2 = img.at<uchar>(i - 1, j);
+				uchar p3 = img.at<uchar>(i - 1, j + 1);
+				uchar p4 = img.at<uchar>(i, j + 1);
+				uchar p5 = img.at<uchar>(i + 1, j + 1);
+				uchar p6 = img.at<uchar>(i + 1, j);
+				uchar p7 = img.at<uchar>(i + 1, j - 1);
+				uchar p8 = img.at<uchar>(i, j - 1);
+				uchar p9 = img.at<uchar>(i - 1, j - 1);
+
+				int C = ((!p2) & (p3 | p4)) + ((!p4) & (p5 | p6)) + ((!p6) & (p7 | p8)) + ((!p8) & (p9 | p2));
+				int N1 = (p9 | p2) + (p3 | p4) + (p5 | p6) + (p7 | p8);
+				int N2 = (p2 | p3) + (p4 | p5) + (p6 | p7) + (p8 | p9);
+				int N = N1 < N2 ? N1 : N2;
+				int m = iter == 0 ? ((p6 | p7 | (!p9)) & p8) : ((p2 | p3 | (!p5)) & p4);
+
+				if ((C == 1) && ((N >= 2) && ((N <= 3)) & (m == 0)))
+					marker.at<uchar>(i, j) = 1;
+			}
+		}
+	}
+
+	img &= ~marker;
+}
+
+// Apply the thinning procedure to a given image
+void thinning(InputArray input, OutputArray output, int thinningType) {
+	Mat processed = input.getMat().clone();
+	// Enforce the range of the input image to be in between 0 - 255
+	processed /= 255;
+
+	Mat prev = Mat::zeros(processed.size(), CV_8UC1);
+	Mat diff, temp;
+
+	do {
+		thinningIteration(processed, 0, thinningType);
+		thinningIteration(processed, 1, thinningType);
+		absdiff(processed, prev, diff);
+		processed.copyTo(prev);
+
+		//// muestra la animacion en cada iteracion del algoritmo
+		//temp = processed * 255;
+		//imshow("test", temp);
+		//waitKey(10);
+		//// end animacion
+
+	} while (countNonZero(diff) > 0);
+
+	processed *= 255;
+
+	output.assign(processed);
+}
+
+
+int main(int argc, char** argv)
+{
+	Mat image = imread("data/star.jpg", CV_LOAD_IMAGE_GRAYSCALE);
+
+	if (image.empty())
+	{
+		printf("No image data \n");
+		return -1;
+	}
+
+	Mat src = image.clone();
+	thinning(src, src, 2);
+
+	// 1. dibujar el esqueleto a color verde sobre la imagen original
+	cvtColor(image, image, CV_GRAY2BGR);
+
+	for (int i = 0; i < image.cols; i++)
+	{
+		for (int j = 0; j < image.rows; j++)
+		{
+			Scalar intensity = src.at<uchar>(j, i);
+			if (intensity.val[0] == 255) {
+				image.at<Vec3b>(j, i) = Vec3b(0, 255, 0);
+			}
+		}
+	}
+	// end 1
+
+	imshow("OpenCV Skeleton Final", src);
+	imshow("Original Skeleton Final", image);
+	waitKey(0);
+
+	return 0;
+}