Merge branch 4.x

modules/imgproc/include/opencv2/imgproc.hpp

@@ -1541,12 +1541,14 @@ respectively (see #getGaussianKernel for details); to fully control the result r
 possible future modifications of all this semantics, it is recommended to specify all of ksize,
 sigmaX, and sigmaY.
 @param borderType pixel extrapolation method, see #BorderTypes. #BORDER_WRAP is not supported.
+@param hint Implementation modfication flags. See #AlgorithmHint
 
 @sa  sepFilter2D, filter2D, blur, boxFilter, bilateralFilter, medianBlur
  */
 CV_EXPORTS_W void GaussianBlur( InputArray src, OutputArray dst, Size ksize,
                                 double sigmaX, double sigmaY = 0,
-                                int borderType = BORDER_DEFAULT );
+                                int borderType = BORDER_DEFAULT,
+                                AlgorithmHint hint = cv::ALGO_HINT_DEFAULT );
 
 /** @brief Applies the bilateral filter to an image.
 
@@ -4084,6 +4086,28 @@ CV_EXPORTS_W void approxPolyDP( InputArray curve,
                                 OutputArray approxCurve,
                                 double epsilon, bool closed );
 
+/** @brief Approximates a polygon with a convex hull with a specified accuracy and number of sides.
+
+The cv::approxPolyN function approximates a polygon with a convex hull
+so that the difference between the contour area of the original contour and the new polygon is minimal.
+It uses a greedy algorithm for contracting two vertices into one in such a way that the additional area is minimal.
+Straight lines formed by each edge of the convex contour are drawn and the areas of the resulting triangles are considered.
+Each vertex will lie either on the original contour or outside it.
+
+The algorithm based on the paper @cite LowIlie2003 .
+
+@param curve Input vector of a 2D points stored in std::vector or Mat, points must be float or integer.
+@param approxCurve Result of the approximation. The type is vector of a 2D point (Point2f or Point) in std::vector or Mat.
+@param nsides The parameter defines the number of sides of the result polygon.
+@param epsilon_percentage defines the percentage of the maximum of additional area.
+If it equals -1, it is not used. Otherwise algorighm stops if additional area is greater than contourArea(_curve) * percentage.
+If additional area exceeds the limit, algorithm returns as many vertices as there were at the moment the limit was exceeded.
+@param ensure_convex If it is true, algorithm creates a convex hull of input contour. Otherwise input vector should be convex.
+ */
+CV_EXPORTS_W void approxPolyN(InputArray curve, OutputArray approxCurve,
+                              int nsides, float epsilon_percentage = -1.0,
+                              bool ensure_convex = true);
+
 /** @brief Calculates a contour perimeter or a curve length.
 
 The function computes a curve length or a closed contour perimeter.