opencv椭圆检测算法（一）

首先轮廓(contour)的定义?

轮廊具有多种多样的定义, 同时这些定义都围绕着物体的边界展开。
无论采用哪种定义方式, 轮廓始终与物体边界有着密切的关系。

那什么是边缘(edge)?

Simple answer: discontinuities in intensity.

边缘的分类?

1. Step edge

2. Ramp edge

3. Ridge edge

4. Roof edge

边缘的描述?

• Edge descriptors
– Edge orientation : unit vector representing the greatest rate of intensity change.
– Edge orthogonal : unit vector perpendicular to the edge orientation.
– Image location where the edge is situated : specifies where within an image an edge can be found.
– The degree of image contrast a