Jinwoo Jeong

Adaptive inter color residual prediction for efficient red-green-blue intra coding

Intra coding of an RGB video is important to many high fidelity multimedia applications because video acquisition is mostly done in RGB space, and the coding of decorrelated color video loses its virtue in high quality ranges. In order to improve the compression performance of an RGB video, this paper proposes an inter color prediction using adaptive weights. For making full use of spatial, as well as inter color correlation of an RGB video, the proposed scheme is based on a residual prediction approach, and thus the incorporated prediction is performed on the transformed frequency components of spatially predicted residual data of each color plane. With the aid of efficient prediction employing frequency domain inter color residual correlation, the proposed scheme achieves up to 24.3% of bitrate reduction, compared to the common mode of H.264/AVC high 4:4:4 intra profile.

Statistical multiplexing using scalable video coding for layered multicast

To provide heterogeneous device capability in the video multicasting/broadcasting, the layered multicast can be exploited. However, previous statistical multiplexing system do not consider to support layered multicast. In order to support heterogenous capability for broadcasting, this paper presents statistical multiplexing system for layered multicast. In proposed system, video sequences for multiple programs are encoded to one base layer stream and several enhancement layer streams, and base layer streams of each program are multiplexed into one single CBR channel and multiple enhancement layers of each program are separately multiplexed into multiple single CBR channels. Furthermore, we allocated different bandwidth for each program using complexity measure in order to achieve similar visual quality among all programs in all layers. Experimental results show that the proposed statistical multiplexing system can efficiently support multiple multiplexed streams for layered multicast and provides a smooth video quality change across programs.

A directional deblocking filter based on intra prediction for H.264/AVC

Although the adaptive deblocking filter of H.264/AVC efficiently reduces blocking artifacts for most images, it is limited in removing the blocking artifacts of the directional edge on the block boundaries. In order to solve this problem, we propose a directional deblocking filter based on intra prediction direction. The proposed algorithm performs directional filtering according to the direction of the intra prediction mode in order to correctly find the block edge while avoiding computational burden. Experimental results show that the proposed algorithm provides subjective improvements at the directional edge and PSNR gain of up to 0.13dB.

Direction-adaptive context modeling for sign coding in embedded wavelet image coder

The conventional embedded wavelet image coder exploiting the adjacent neighbors is limited to efficiently compress the sign coefficients, since the wavelet coefficients are highly correlated along the dominant image features, such as edges or contours. To solve the problem, in this paper, we propose the direction-adaptive sign context modeling by adaptively exploiting the neighbors suitable to the dominant image features. Experimental results show that the sign coding based on the proposed context modeling reduces the sign bits up to 5.5% compared to the conventional sign coding method.

RGB video coding using the matched neighbourhood block in the inter-color plane

H.264/AVC High 4:4:4 Intra/Predictive profiles supports RGB 4:4:4 sequences for high fidelity video. RGB color planes rather than YCbCr color planes are preferred by high-fidelity video applications such as digital cinema, medical imaging, and UHDTV. Several RGB coding tools have therefore been developed to improve the coding efficiency of RGB video. In this paper, we propose a new method to extract more accurate correlation parameters for inter-plane prediction. We use a searching method to determine the matched macroblock (MB) that has a similar inter-color relation to the current MB. Using this block, we can infer more accurate correlation parameters to predict chroma MB from luma MB. Our proposed inter-plane prediction mode shows an average bits saving of 15.6% and a PSNR increase of 0.99dB compared with H.264 high4:4:4 intra-profile RGB coding. Furthermore, extensive performance evaluation revealed that our proposed algorithm has better coding efficiency than existing algorithms.

Selective intra-prediction Skip Algorithm for inter-frame coding in H.264/AVC

Inter-frame coding using inter- and intra-predictions plays an important role in achieving high compression efficiency in H.264/AVC. However, most intra-predictions are unnecessary, since the intra-coding mode occupies less than 5% of the overall coding in inter-frame coding. In this paper, we propose an intra mode skip algorithm for inter-frame coding in H.264/AVC as a means of obtaining fast intra mode decision. The algorithm uses the joint entropy (JE) and mutual information (MI) to extract the temporal correlations between the current block and the reconstructed block based on 8 × 8 motion estimation. All or part of the intra-prediction search is omitted by using JE and MI. Experimental results show that the proposed algorithm is capable of reducing the overall coding time by 15-37% and the overall intra-prediction time by 32-78% compared to full search of the reference software, with negligible loss of quality.

Most probable mode-based fast 4 × 4 intra-prediction in H.264/AVC

The H.264/AVC uses the rate distortion optimization (RDO) method as a measure to select the optimal coding mode. However, the computational complexity for RDO calculation is increased due to the various coding modes. In this paper, we analyzes that the best mode decision for 4 times 4 intra-prediction can be affected according to the relation of most probable mode (MPM) and prediction mode. With this understanding, we propose an algorithm for fast 4 times 4 intra-prediction mode selection based on the MPM in the H.264/AVC encoder. A defined rate distortion (RD) cost, including the minimum bit for signaling the prediction modes except the MPM, is used as a threshold for fast 4 times 4 intra-prediction. Experimental results show that the proposed algorithm is capable of reducing the overall encoding time by 27-29% and the overall intra-prediction time by 35% compared to full search of the reference software, without loss of quality.

Enhanced Film Grain Noise Removal for High Fidelity Video Coding

In this paper, we propose a novel technique for film grain noise removal, which can be adopted in high fidelity video coding. Film grain noise enhances the natural appearance of high fidelity video, therefore it is should be preserved. However, film grain noise is a burden to typical video compression systems because it has relatively large energy level in the high frequency region. In order to improve the coding performance while preserving film grain noise, the noise removal and synthesis process is used. We propose a film grain noise removal technology in the pre-processing step. In pre-processing step, film grain noise is removed by using temporal, spatial and inter-color correlation. Specially, color image denoisng using inter color prediction provides good denoising performance in noise concentrated B plane because film grain noise has inter-color correlation in the RGB domain. The results show that the coding gain of denoised video is higher than for previous works, while the visual quality of the final reconstructed video is well preserved.

An adaptive frequency-selective weighted prediction of residual signal for efficient RGB video compression coding

요 약대부분의비디오부호화시스템은 색공간에서부호화가수행되나초고화질비디오가사용되는분야에서는 색공간YCbCr YCbCr에서부호화하는것이 색공간에서부호화는것에비해높은압축효율을제공하지않기때문에 공간에서부호화하는것RGB RGB이선호된다 비디오신호의압축부호화효율을증대시키기위하여본논문은잔여신호의적응적주파수선택가중예측기법. RGB -을제안한다 비디오신호의색평면간상관도를최대한활용하기위해제안기법은잔여신호평면사이의주파수영역에서의. RGB ,부호일치도와상관강도에근거하여적응적으로잔여신호평면간예측될주파수영역과그에상응하는예측가중치를선택한다실.험결과는최신의비디오압축표준인 에서 비디오부호화의공통모드에비해약 정도압축부호화성능을개H.264/AVC 4:4:4 13%선시켰음을보여준다.AbstractMostvideocodingsystemsuseYCbCrcolorspacefortheirinputs,butRGBspaceismorepreferredinthefieldofhighfidelityvideobecause the compression gain from YCbCr becomes disappeared in the high quality operation region. In order to improve the codingperformance of RGB video signal, this paper presents an adaptive frequency-selective weighted prediction algorithm. Based on the signagreementandthestrengthoffrequency-domaincorrelationofresidualcolorplanes,theproposedschemeadaptivelyselectsthefrequencyelementsaswellasthecorrespondingpredictionweightsforbetterutilizationofinter-planecorrelationofRGBsignal.Experimentalresultsshowedthattheproposedalgorithmimprovesthecodinggainofaround13%bitratereduction,onaverage,comparedtothecommonmodeof4:4:4videocodinginthestate-of-the-artvideocompressionstandard,H.264/AVC.Keyword : RGB video coding, Residual color space transform, selective prediction scheme

An efficient skip mode competition scheme based on vector clustering and object boundary detection

In video coding, a portion of skipped macroblocks is highly effective to the coding performance, especially, at low bitrates since, for a skip mode, no additional coding parameters are transmitted except mode index itself. To increase the skip mode occurrence, in this paper, we propose an efficient skip mode competition scheme based on vector clustering of multiple predictive motion vectors (PMV) and boundary detection of moving objects. The proposed scheme selects the best PMV of skip mode optimally among representative PMV candidates which are obtained after the clustering process and switches a more appropriate competition scheme adaptively according to object boundary conditions. Experimental results show that the proposed scheme reduces average 4.31% in BDRATE compared to the KTA 2.6 software.