基于轮廓和链码表示的高效形状编码

High efficient shape coding based on the representation of contour and chain code

提出一种基于轮廓和链码表示的高效无损形状编码方法。首先提取对象轮廓并细化成单像素宽度;然后将其转换成链码表示并基于方向相关性分割成若干子段,使每个子段最多包含2个基本方向码,同时结合线性检测,分离出对象轮廓中的长线性子段;最后对线性子段和非线性子段结合链码的空域相关性进行差异化编码以获得最佳编码性能。实验结果显示,所提算法的性能优于现有的常用方法,与最新的同类方法相比能平均提高压缩效率36.5%左右。

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 tcquire high coding performance. Experiments are conducted and the results show that the proposed scheme outperforms the existing tech- niques and can improve the compression efficiency by 36.5% on average compared with the state-of-the-art method.