1. Find and contouring
(1) Looking outline: findContours () function
Note:
(2) contouring: drawContours () function
层次结构信息：https://blog.csdn.net/qq_36387683/article/details/80472043
2. Find the convex hull of the object
(1) the convex hull concept:
(2) Find the convex hull function: convexHull ()
The polygonal contour extraction
(1) Returns the outer boundary of the matrix: boundingRect () function
(2) find minimum surrounding matrix: minAreaRect () function
(3) Find the smallest enclosing circle: minEnclosingCiecle () function
(4) with a two-dimensional ellipse fitting point set: fitEllipse () function
(4) a polygonal approximation curve: approxPolyDP () function
注：轮廓vertor容器contours[i]应该是包含了很多坐标信息，比如一个contours[0]就是一个轮廓的二维坐标点集
4. The image moments: in fact an integrated characteristic descriptors (translation satisfied, stretching, rotation invariance), which can calculate the length and area
Moment of the image (1) opencv in
(2 moment calculation function: moments () - this function can return a value as a parameter, a function is calculated by contourArea () and arcLength () area and length
(3) calculate the contour area : contourArea () 
(. 4) to calculate the contour length: arcLength () function
opencv in the member variable understood Moments : https: //blog.csdn.net/ZZS_SZZ/article/details/84778584
(5) watershed algorithm
how feeling "diffuse water filling algorithm" and "watershed filling algorithm," the core idea almost
diffuse water filling algorithm (mainly seed sorting point, then set the threshold automatically selected regional and seed point is connected, then Alternatively the area with a specified color): https: //blog.csdn.net/qq_31531635/article/details/73337887
mask (cover off is unnecessary portion): with a selected image, or a graphic object, treated image (wholly or partially) blocking process performed to control the area or the image processing process. For covering a particular image or object referred to as a mask or template.
(1) watershed () function
The image patch
(1) inpainting function: inpaint () function
to sum up
