中文说明：链码是曲线起始点的坐标和边界点方向代码来描述曲线或边界的方法，常被用来咋图像处理，计算图形学，模式识别等领域中表示曲线和区域边界，常用的链码按照中心像素点领域方向个数的不同分为4连通和8连通链码。
English Description：
Chain code is the starting point of the curve coordinates and the boundary point direction code to describe the boundary curves or, which are often used in Zha image processing, computer graphics, pattern recognition in the field of said curve and the boundary of the region, the commonly used the chain codes according to the number of pixels direction in the field of center not with 4 connected and 8-connected chain code.