Added a sample to show usage of the class.

modules/imgproc/include/opencv2/imgproc.hpp

@@ -899,7 +899,7 @@ public:
  * @param lines2    The second lines that need to be drawn. Color - Red.
  * @return          The number of mismatching pixels between lines1 and lines2.
  */
-    static int compareSegments(cv::Size& size, const std::vector<cv::Vec4i>& lines1, const std::vector<cv::Vec4i> lines2, cv::Mat* image = 0);
+    static int compareSegments(const cv::Size& size, const std::vector<cv::Vec4i>& lines1, const std::vector<cv::Vec4i> lines2, cv::Mat* image = 0);
 
 private:
     cv::Mat image;

modules/imgproc/src/lsd.cpp

@@ -957,13 +957,15 @@ void LSD::drawSegments(cv::Mat& image, const std::vector<cv::Vec4i>& lines)
     }
 }
 
-int LSD::compareSegments(cv::Size& size, const std::vector<cv::Vec4i>& lines1, const std::vector<cv::Vec4i> lines2, cv::Mat* image)
+
+int LSD::compareSegments(const cv::Size& size, const std::vector<cv::Vec4i>& lines1, const std::vector<cv::Vec4i> lines2, cv::Mat* image)
 {
-    if (image && image->size() != size) size = image->size();
-    CV_Assert(size.area());
+    Size sz = size;
+    if (image && image->size() != size) sz = image->size();
+    CV_Assert(sz.area());
 
-    Mat_<uchar> I1 = Mat_<uchar>::zeros(size);
-    Mat_<uchar> I2 = Mat_<uchar>::zeros(size);
+    Mat_<uchar> I1 = Mat_<uchar>::zeros(sz);
+    Mat_<uchar> I2 = Mat_<uchar>::zeros(sz);
 
     // Draw segments
     for(unsigned int i = 0; i < lines1.size(); ++i)

samples/cpp/lsd_lines.cpp

+#include <iostream>
+#include <string>
+
+#include "opencv2/core/core.hpp"
+#include "opencv2/imgproc/imgproc.hpp"
+#include "opencv2/highgui/highgui.hpp"
+
+using namespace std;
+using namespace cv;
+
+int main(int argc, char** argv)
+{
+	if (argc != 2) 
+	{
+		std::cout << "lsd_lines [input image]" << std::endl;
+		return false;
+	}
+	
+	std::string in = argv[1];
+
+	Mat image = imread(in, CV_LOAD_IMAGE_GRAYSCALE);
+
+	// Create and LSD detector with std refinement.
+	LSD lsd_std(LSD_REFINE_STD);
+	double start = double(getTickCount());
+	vector<Vec4i> lines_std;
+	lsd_std.detect(image, lines_std);
+	double duration_ms = (double(getTickCount()) - start) * 1000 / getTickFrequency();
+	std::cout << "OpenCV STD (blue) - " << duration_ms << " ms." << std::endl;
+	
+	// Create an LSD detector with no refinement applied.
+	LSD lsd_none(LSD_REFINE_NONE);
+	start = double(getTickCount());
+	vector<Vec4i> lines_none;
+	lsd_none.detect(image, lines_none);
+	duration_ms = (double(getTickCount()) - start) * 1000 / getTickFrequency();
+	std::cout << "OpenCV NONE (red)- " << duration_ms << " ms." << std::endl;
+	std::cout << "Overlapping pixels are shown in purple." << std::endl;
+	
+	Mat difference = Mat::zeros(image.size(), CV_8UC1); 
+	LSD::compareSegments(image.size(), lines_std, lines_none, &difference);
+	imshow("Line difference", difference);
+
+	Mat drawnLines(image);
+	LSD::drawSegments(drawnLines, lines_std);
+	imshow("Standard refinement", drawnLines);
+
+	waitKey();
+	return 0;
+}