Abstract: A high efficient lossless shape coding scheme was proposed based on the representation of contour and chain code. The object contours are firstly extracted and thinned to be single-pixel width. Then the object contours are transformed into chain-code-based representation and divided into different sub-segments based on link directions to make each sub-segment consist of up to two types of links. Thirdly, straightness detection is performed and long straight-line segments within contours are separated. Finally, different schemes are proposed to encode the straight-line sub-segments and ordinary curve sub-segments by employing the spatial correlations among contours aiming to acquire high coding performance. Experiments are conducted and the results show that the proposed scheme outperforms the existing techniques and can improve the compression efficiency by 36.5% on average compared with the state-of-the-art method.