Merge pull request #2915 from alalek:backport_2716

Author: alalek

modules/ximgproc/include/opencv2/ximgproc/fast_line_detector.hpp

@@ -65,8 +65,9 @@ class CV_EXPORTS_W FastLineDetector : public Algorithm
                                          hysteresis procedure in Canny()
 @param _canny_th2           50         - Second threshold for
                                          hysteresis procedure in Canny()
-@param _canny_aperture_size 3          - Aperturesize for the sobel
-                                         operator in Canny()
+@param _canny_aperture_size 3          - Aperturesize for the sobel operator in Canny().
+                                         If zero, Canny() is not applied and the input
+                                         image is taken as an edge image.
 @param _do_merge            false      - If true, incremental merging of segments
                                          will be performed
 */

modules/ximgproc/samples/fld_lines.cpp

@@ -37,8 +37,9 @@ int main(int argc, char** argv)
     //                                     hysteresis procedure in Canny()
     // canny_th2           50            - Second threshold for
     //                                     hysteresis procedure in Canny()
-    // canny_aperture_size 3             - Aperturesize for the sobel
-    //                                     operator in Canny()
+    // canny_aperture_size 3            - Aperturesize for the sobel operator in Canny().
+    //                                     If zero, Canny() is not applied and the input
+    //                                     image is taken as an edge image.
     // do_merge            false         - If true, incremental merging of segments
     //                                     will be performed
     int length_threshold = 10;

modules/ximgproc/src/fast_line_detector.cpp

@@ -29,10 +29,11 @@ class FastLineDetectorImpl : public FastLineDetector
          *        _                                 hysteresis procedure in Canny()
          * @param _canny_th2           50         - Second threshold for
          *        _                                 hysteresis procedure in Canny()
-         * @param _canny_aperture_size 3          - Aperturesize for the sobel
-         *        _                                 operator in Canny()
+         * @param _canny_aperture_size 3          - Aperturesize for the sobel operator in Canny().
+         *                                          If zero, Canny() is not applied and the input
+         *                                          image is taken as an edge image.
          * @param _do_merge            false      - If true, incremental merging of segments
-                                                   will be perfomred
+         *                                          will be performed
          */
         FastLineDetectorImpl(int _length_threshold = 10, float _distance_threshold = 1.414213562f,
                 double _canny_th1 = 50.0, double _canny_th2 = 50.0, int _canny_aperture_size = 3,
@@ -80,7 +81,7 @@ class FastLineDetectorImpl : public FastLineDetector
 
         double distPointLine(const Mat& p, Mat& l);
 
-        void extractSegments(const std::vector<Point2i>& points, std::vector<SEGMENT>& segments );
+        void extractSegments(const std::vector<Point2i>& points, std::vector<SEGMENT>& segments);
 
         void lineDetection(const Mat& src, std::vector<SEGMENT>& segments_all);
 
@@ -113,7 +114,7 @@ FastLineDetectorImpl::FastLineDetectorImpl(int _length_threshold, float _distanc
     canny_th1(_canny_th1), canny_th2(_canny_th2), canny_aperture_size(_canny_aperture_size), do_merge(_do_merge)
 {
     CV_Assert(_length_threshold > 0 && _distance_threshold > 0 &&
-            _canny_th1 > 0 && _canny_th2 > 0 && _canny_aperture_size > 0);
+            _canny_th1 > 0 && _canny_th2 > 0 && _canny_aperture_size >= 0);
 }
 
 void FastLineDetectorImpl::detect(InputArray _image, OutputArray _lines)
@@ -344,7 +345,7 @@ template<class T>
         pt = T(pt_tmp);
     }
 
-void FastLineDetectorImpl::extractSegments(const std::vector<Point2i>& points, std::vector<SEGMENT>& segments )
+void FastLineDetectorImpl::extractSegments(const std::vector<Point2i>& points, std::vector<SEGMENT>& segments)
 {
     bool is_line;
 
@@ -544,8 +545,14 @@ void FastLineDetectorImpl::lineDetection(const Mat& src, std::vector<SEGMENT>& s
     std::vector<Point2i> points;
     std::vector<SEGMENT> segments, segments_tmp;
     Mat canny;
-    Canny(src, canny, canny_th1, canny_th2, canny_aperture_size);
-
+    if (canny_aperture_size == 0)
+    {
+        canny = src;
+    }
+    else
+    {
+        Canny(src, canny, canny_th1, canny_th2, canny_aperture_size);
+    }
     canny.colRange(0,6).rowRange(0,6) = 0;
     canny.colRange(src.cols-5,src.cols).rowRange(src.rows-5,src.rows) = 0;
 

modules/ximgproc/test/test_fld.cpp

@@ -23,6 +23,7 @@ class FLDBase : public testing::Test
         void GenerateWhiteNoise(Mat& image);
         void GenerateConstColor(Mat& image);
         void GenerateLines(Mat& image, const unsigned int numLines);
+        void GenerateEdgeLines(Mat& image, const unsigned int numLines);
         void GenerateBrokenLines(Mat& image, const unsigned int numLines);
         void GenerateRotatedRect(Mat& image);
         virtual void SetUp();
@@ -55,6 +56,7 @@ void FLDBase::GenerateConstColor(Mat& image)
     image = Mat(img_size, CV_8UC1, Scalar::all(rng.uniform(0, 256)));
 }
 
+
 void FLDBase::GenerateLines(Mat& image, const unsigned int numLines)
 {
     image = Mat(img_size, CV_8UC1, Scalar::all(rng.uniform(0, 128)));
@@ -68,6 +70,19 @@ void FLDBase::GenerateLines(Mat& image, const unsigned int numLines)
     }
 }
 
+void FLDBase::GenerateEdgeLines(Mat& image, const unsigned int numLines)
+{
+    image = Mat(img_size, CV_8UC1, Scalar::all(0));
+
+    for(unsigned int i = 0; i < numLines; ++i)
+    {
+        int y = rng.uniform(10, img_size.width - 10);
+        Point p1(y, 10);
+        Point p2(y, img_size.height - 10);
+        line(image, p1, p2, Scalar(255), 1);
+    }
+}
+
 void FLDBase::GenerateBrokenLines(Mat& image, const unsigned int numLines)
 {
     image = Mat(img_size, CV_8UC1, Scalar::all(rng.uniform(0, 128)));
@@ -153,6 +168,19 @@ TEST_F(ximgproc_FLD, lines)
     ASSERT_EQ(EPOCHS, passedtests);
 }
 
+TEST_F(ximgproc_FLD, edgeLines)
+{
+    for (int i = 0; i < EPOCHS; ++i)
+    {
+        const unsigned int numOfLines = 1;
+        GenerateEdgeLines(test_image, numOfLines);
+        Ptr<FastLineDetector> detector = createFastLineDetector(10, 1.414213562f, 50, 50, 0);
+        detector->detect(test_image, lines);
+        if(numOfLines == lines.size()) ++passedtests;
+    }
+    ASSERT_EQ(EPOCHS, passedtests);
+}
+
 TEST_F(ximgproc_FLD, mergeLines)
 {
     for (int i = 0; i < EPOCHS; ++i)