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A DWT-based lossless intra coding scheme for HEVC

To improve the intra lossless video coding efficiency by introducing frequency domain compression, this paper presents a new intra coding scheme for lossless mode in HEVC. The proposed method utilizes reversible lifting DWT and DC level shifting to transform one frame into four sub-bands of frequency coefficients for the original coding tools to process. To recover the transformed frequency coefficients of signed type loss-lessly, a modified reconstruction are applied to HEVC. By implementing the method in HM-16.5 reference software, the experimental results show that compared with the original HEVC lossless intra coding, the new scheme can achieve 7.122% bitrate saving and take 92.443% encoding time averagely.