Perceptual feedback in multigrid motion estimation using an improved DCT quantization

Abstract

Abstract-In this paper, a multigrid motion compensation video coder based on the current human visual system (HVS) contrast discrimination models is proposed. A novel procedure for the encoding of the prediction errors has been used. This procedure restricts the maximum perceptual distortion in each transform coefficient. This subjective redundancy removal procedure includes the amplitude nonlinearities and some temporal features of human perception. A perceptually weighted control of the adaptive motion estimation algorithm has also been derived from this model. Perceptual feedback in motion estimation ensures a perceptual balance between the motion estimation effort and the redundancy removal process. The results show that this feedback induces a scaledependent refinement strategy that gives rise to more robust and meaningful motion estimation, which may facilitate higher level sequence interpretation. Perceptually meaningful distortion measures and the reconstructed frames show the subjective improvements of the proposed scheme versus an H.263 scheme with unweighted motion estimation and MPEG-like quantization.Index Terms-Entropy constrained motion estimation, nonlinear human vision model, perceptual quantization, video coding.

Human visual system based adaptive inter quantization

“…al. [3] proposed a multigrid motion compensation video coding scheme based on HVS. However, it consumes a lot of memory and is not suitable for digital applications with restrict battery lifetime such as mobile video.…”

Normalized image representation for efficient coding

“…The difference between the approaches that implicitly followed the MPE idea [2], [14]- [18] is the accuracy of the perception model which is used to propose the perceptually Euclidean domain. For instance, the quantization scheme (empirically) recommended in the JPEG standard [16] may be deduced from the MPE restriction with a very simple linear vision model based on the CSF [14].…”

“…In this very simple case, it is assumed that no perceptual relationship exists between the coefficients of the transform, and that the perceptual relevance of each coefficient is given by the corresponding CSF value. The performance of this approach can be improved at around 0.5 bits/pix if a more sophisticated model is used [14], [15], [17], [18]. In these references the authors used a point-wise non-linear model in the DCT domain.…”

“…5, top-left), the algorithm of Malo et al [14], [18], that assumes a point-wise non-linear model [11] and hence an input-dependent diagonal metric in the DCT domain ( fig. 5, top-right), the algorithm of Epifanio et al [2], that assumes a fixed non-diagonal metric in the DCT domain ( fig.…”

“…These results show that removing or reducing the remaining (statistical and perceptual) dependence in linear transforms may make a big difference in the quality of the reconstructed images. Objective (MSE) and subjective (Perceptual MSE [2], [14], [18]) distortions at different bit rates (in parenthesis, in bit/pix). [16].…”