Arbitrary shaped ROI image coding using Run-length coding and generalized Exp-Golomb coding
徐勇 Xu Yong, 徐智勇 Xu Zhiyong, 张启衡 Zhang Qiheng · Optics and Precision Engineering · 2011
A context adaptive tri-element Run length coding algorithm and an Exp-Golomb coding alogorithm were introduced.The Run-length coding was used to model the image wavelet coefficients and the Region of Interest(ROI) mask and to yield tri-element codes.Then,the conventional Exp-Golomb coding was expanded to encode tri-element codes from Run-length coding and to carry the ROI mask together.Based on the two algorithms above,a high efficient algorithm to distinguish the ROI and background was obtained and a ROI codec framework was proposed.The framework includes 5/3 wavelet transform,wavelet domain mask generation,non-uniform optimal quantization,context adaptive tri-element Run-length coding and generalized Exp-Golomb coding.The tri-element Run-length coding in this algorithm is brief,and the expanded Exp-Golomb coding can be expressed by a closed formula.Experimental results show that the algorithm supports multiple arbitrary-shaped ROI and the adjustability of the ROI is prior to that of the background region.Furthermore,it achieves higher compressing performance as compared with the BbB-shift based SPIHT compression algorithm.