implemented DP-based seam estimation method

modules/stitching/include/opencv2/stitching/detail/seam_finders.hpp

@@ -43,6 +43,7 @@
 #ifndef __OPENCV_STITCHING_SEAM_FINDERS_HPP__
 #define __OPENCV_STITCHING_SEAM_FINDERS_HPP__
 
+#include <set>
 #include "opencv2/core/core.hpp"
 #include "opencv2/opencv_modules.hpp"
 
@@ -92,6 +93,114 @@ private:
 };
 
 
+class CV_EXPORTS DpSeamFinder : public SeamFinder
+{
+public:
+    enum CostFunction { COLOR, COLOR_GRAD };
+
+    DpSeamFinder(CostFunction costFunc = COLOR_GRAD);
+
+    CostFunction costFunction() const { return costFunc_; }
+    void setCostFunction(CostFunction val) { costFunc_ = val; }
+
+private:
+    enum ComponentState
+    {
+        FIRST = 1, SECOND = 2, INTERS = 4,
+        INTERS_FIRST = INTERS | FIRST,
+        INTERS_SECOND = INTERS | SECOND
+    };
+
+    class ImagePairLess
+    {
+    public:
+        ImagePairLess(const std::vector<Mat> &images, const std::vector<Point> &corners)
+            : src_(&images[0]), corners_(&corners[0]) {}
+
+        bool operator() (const std::pair<int, int> &l, const std::pair<int, int> &r) const
+        {
+            Point c1 = corners_[l.first] + Point(src_[l.first].cols / 2, src_[l.first].rows / 2);
+            Point c2 = corners_[l.second] + Point(src_[l.second].cols / 2, src_[l.second].rows / 2);
+            int d1 = (c1 - c2).dot(c1 - c2);
+
+            c1 = corners_[r.first] + Point(src_[r.first].cols / 2, src_[r.first].rows / 2);
+            c2 = corners_[r.second] + Point(src_[r.second].cols / 2, src_[r.second].rows / 2);
+            int d2 = (c1 - c2).dot(c1 - c2);
+
+            return d1 < d2;
+        }
+
+    private:
+        const Mat *src_;
+        const Point *corners_;
+    };
+
+    class ClosePoints
+    {
+    public:
+        ClosePoints(int minDist) : minDist_(minDist) {}
+
+        bool operator() (const Point &p1, const Point &p2) const
+        {
+            int dist2 = (p1.x-p2.x) * (p1.x-p2.x) + (p1.y-p2.y) * (p1.y-p2.y);
+            return dist2 < minDist_ * minDist_;
+        }
+
+    private:
+        int minDist_;
+    };
+
+    virtual void find(const std::vector<Mat> &src, const std::vector<Point> &corners,
+                      std::vector<Mat> &masks);
+
+    void process(const Mat &image1, const Mat &image2, Point tl1, Point tl2,
+                 Mat &mask1, Mat &mask2);
+
+    void findComponents();
+
+    void findEdges();
+
+    void resolveConflicts(const Mat &image1, const Mat &image2,
+                          Point tl1, Point tl2, Mat &mask1, Mat &mask2);
+
+    void computeGradients(const Mat &image1, const Mat &image2);
+
+    bool hasOnlyOneNeighbor(int c);
+
+    bool closeToContour(int y, int x, const Mat_<uchar> &contourMask);
+
+    bool getSeamTips(int c1, int c2, Point &p1, Point &p2);
+
+    void computeCosts(const Mat &image1, const Mat &image2, Point tl1, Point tl2,
+                      int c, Mat_<float> &costV, Mat_<float> &costH);
+
+    bool estimateSeam(
+            const Mat &image1, const Mat &image2, Point tl1, Point tl2, int c,
+            Point p1, Point p2, std::vector<Point> &seam, bool &isHorizontal);
+
+    void updateLabelsUsingSeam(int c1, int c2, const std::vector<Point> &seam,
+                               bool isHorizontalSeam);
+
+    CostFunction costFunc_;
+
+    // processing images pair data
+    Point unionTl_, unionBr_;
+    Size unionSize_;
+    Mat_<uchar> mask1_, mask2_;
+    Mat_<uchar> contour1mask_, contour2mask_;
+    Mat_<float> gradx1_, grady1_;
+    Mat_<float> gradx2_, grady2_;
+
+    // components data
+    int ncomps_;
+    Mat_<int> labels_;
+    std::vector<ComponentState> states_;
+    std::vector<Point> tls_, brs_;
+    std::vector<std::vector<Point> > contours_;
+    std::set<std::pair<int, int> > edges_;
+};
+
+
 class CV_EXPORTS GraphCutSeamFinderBase
 {
 public:

samples/cpp/stitching_detailed.cpp

@@ -276,7 +276,9 @@ static int parseCmdArgs(int argc, char** argv)
             if (string(argv[i + 1]) == "no" ||
                 string(argv[i + 1]) == "voronoi" ||
                 string(argv[i + 1]) == "gc_color" ||
-                string(argv[i + 1]) == "gc_colorgrad")
+                string(argv[i + 1]) == "gc_colorgrad" ||
+                string(argv[i + 1]) == "dp_color" ||
+                string(argv[i + 1]) == "dp_colorgrad")
                 seam_find_type = argv[i + 1];
             else
             {
@@ -612,6 +614,10 @@ int main(int argc, char* argv[])
 #endif
             seam_finder = new detail::GraphCutSeamFinder(GraphCutSeamFinderBase::COST_COLOR_GRAD);
     }
+    else if (seam_find_type == "dp_color")
+        seam_finder = new detail::DpSeamFinder(DpSeamFinder::COLOR);
+    else if (seam_find_type == "dp_colorgrad")
+        seam_finder = new detail::DpSeamFinder(DpSeamFinder::COLOR_GRAD);
     if (seam_finder.empty())
     {
         cout << "Can't create the following seam finder '" << seam_find_type << "'\n";