ABSTRACT In the Di erential Pulse-code Modulation (DPCM) image coding, the intensity of a pixel is predicted as a linearcombination of a set of surrounding pixels and the prediction error is encoded. In this paper, we propose theadaptive residual DPCM (ARDPCM) for intra lossless coding. In the ARDPCM, intra residual samples arepredicted using adaptive mode-dependent DPCM weights. The weights are estimated by minimizing the MeanSquared Error (MSE) of coded data and they are synchronized at the encoder and the decoder. The proposedmethod is implemented on the High Eciency Video Coding (HEVC) reference software. Experimental resultsshow that the ARDPCM signi cantly outperforms HEVC lossless coding and HEVC with the DPCM. Theproposed method is also computationally ecient.Keywords: Lossless coding, DPCM, HEVC, adaptive 1. INTRODUCTION In image and video compression, lossless coding is used for perfect preservation of visual data. The perfectpreservation property is desirable in many image and video applications. For example, lossless coding can beused in preserving watermark information embedded in images and videos. In video editing, lossless coding canprevent accumulation of quantization error when the video is repeatedly encoded. In addition, lossless codingcan be used to accurately preserve numerical data for further processing, such as in medical imaging applications.In many image and video compression systems, the Two-dimensional Discrete Cosine Transform (2D-DCT)[1] is used for lossy coding. The 2D-DCT, however, can not be applied to lossless coding in a straightforwardmanner. DCT coecients have to be quantized before they are encoded. The quantization error creates aproblem for the perfect preservation requirement in lossless coding. As a result, many approaches have beenproposed to replace the 2D-DCT in lossless coding.One approach is based on transforms. In the methods based on this approach, images or prediction residualsare transformed into integer transform coecients. Transform coecients are coded without quantization. Forexample, in JPEG 2000 lossless image coding [2], 5/3 integer lifting wavelet transform is used. In the VP9 videocoding standard [3], the Walsh-Hadamard transform [4] is used in lossless coding. In the work reported in [5]and [6], prediction residuals are transformed into two domains and encoded separately.Another approach is based on the PCM of prediction residuals. This method is used in the HEVC standard.Speci cally, prediction residuals are rst obtained. The prediction residuals are coded directly by the entropycoder. Transform and quantization steps are bypassed in HEVC lossless coding [7].The third approach is based on the DPCM. The DPCM is rst proposed in [8] for H.264 [9][10][11] intralossless coding. In this proposal, directional intra prediction modes are replaced with the sample-wise DPCM onimage intensities of the same direction. For example, consider the case where the vertical DPCM is used. Theimage pixel to be coded is subtracted from the one immediately above it. The DPCM prediction error is thenencoded. The DPCM can be used for other directions in a similar way. This strategy is adopted in the latest
['Xun Cai', 'Jae S. Lim']
Adaptive residual DPCM for lossless intra coding