added description of cv::convexityDefect

modules/imgproc/doc/structural_analysis_and_shape_descriptors.rst

@@ -396,13 +396,19 @@ ConvexityDefects
 ----------------
 Finds the convexity defects of a contour.
 
+.. ocv:function:: void convexityDefects( InputArray points, InputArray convexhull, OutputArray convexityDefects )
+
+.. ocv:pyfunction:: cv2.ConvexityDefects(contour, convexhull)-> convexityDefects
+
 .. ocv:cfunction:: CvSeq* cvConvexityDefects(  const CvArr* contour, const CvArr* convexhull, CvMemStorage* storage=NULL )
 
 .. ocv:pyoldfunction:: cv.ConvexityDefects(contour, convexhull, storage)-> convexityDefects
 
     :param contour: Input contour. 
     
-    :param convexhull: Convex hull obtained using  :ocv:cfunc:`ConvexHull2`  that should contain pointers or indices to the contour points, not the hull points themselves (the  ``returnPoints``  parameter in  :ocv:cfunc:`ConvexHull2`  should be zero). 
+    :param convexhull: Convex hull obtained using  :ocv:func:`convexHull`  that should contain indices of the contour points that make the hull. 
+
+    :param convexityDefects: The output vector of convexity defects. In C++ and the new Python/Java interface each convexity defect is represented as 4-element integer vector (a.k.a. ``cv::Vec4i``): ``(start_index, end_index, farthest_pt_index, fixpt_depth)``, where indices are 0-based indices in the original contour of the convexity defect beginning, end and the farthest point, and ``fixpt_depth`` is fixed-point approximation (with 8 fractional bits) of the distance between the farthest contour point and the hull. That is, to get the floating-point value of the depth will be ``fixpt_depth/256.0``. In C interface convexity defect is represented by ``CvConvexityDefect`` structure - see below.
     
     :param storage: Container for the output sequence of convexity defects. If it is NULL, the contour or hull (in that order) storage is used.