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(3.4) ximgproc: Added edge input feature to fast_line_detector #2915

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Apr 7, 2021
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(3.4) ximgproc: Added edge input feature to fast_line_detector #2915

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5 changes: 3 additions & 2 deletions modules/ximgproc/include/opencv2/ximgproc/fast_line_detector.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -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
*/
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5 changes: 3 additions & 2 deletions modules/ximgproc/samples/fld_lines.cpp
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Expand Up @@ -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;
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23 changes: 15 additions & 8 deletions modules/ximgproc/src/fast_line_detector.cpp
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Expand Up @@ -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,
Expand Down Expand Up @@ -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);

Expand Down Expand Up @@ -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)
Expand Down Expand Up @@ -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;

Expand Down Expand Up @@ -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;

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28 changes: 28 additions & 0 deletions modules/ximgproc/test/test_fld.cpp
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Expand Up @@ -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();
Expand Down Expand Up @@ -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)));
Expand All @@ -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)));
Expand Down Expand Up @@ -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)
Expand Down