链码技术被广泛应用是因为它能以较少的数据来贮存较多的信息。用链码来表示线条模式的方法是由 Freeman 首先提出来的。Freeman 链码至今仍然是一个被广泛使用的最主要的链码编码方法。 -Chain code technology is widely used because it can be less data to store more information. With a chain code representation of the line model it is first proposed by the Freeman. Freeman chain code is still the main chain coding method is widely used.