Chain code

The encoder then moves along the boundary of the region and, at each step, transmits a symbol representing the direction of this movement.

This encoding method is particularly effective for images consisting of a reasonably small number of large connected components.

This started by the work of Mouring et al.[6] who developed an algorithm that takes advantage of the pheromone of ants to track image information.

Recently, the combination of move-to-front transform and adaptive run-length encoding accomplished efficient compression of the popular chain codes.

[14] Chain codes also can be used to obtain high levels of compression for image documents, outperforming standards such as DjVu and JBIG2.