• Journal of Broadcast Engineering
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• v.18 no.2
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• pp.283-296
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• 2013

Various video services with networks are increasingly available as smart phones, computers and IPTV are widely used. However, transmission over networks may experience transmission errors due to traffic increases and noise. As a result, video quality may suffer. Therefore, quality monitoring emerges as an important issue. In this paper, we propose a video quality assessment method using bit stream information. The video quality metric is calculated using header information and ES (elementary stream) information. To assess performance of the proposed algorithm, subjective quality assessment tests are conducted (VGA resolution). It is shown high correlation between subjective result and the proposed method.

• Journal of Communications and Networks
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• v.9 no.4
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• pp.446-456
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• 2007

Increased access to broadband networks has led to a fast-growing demand for voice and video over IP(VVoIP) applications such as Internet telephony(VoIP), videoconferencing, and IP television(IPTV). For pro-active troubleshooting of VVoIP performance bottlenecks that manifest to end-users as performance impairments such as video frame freezing and voice dropouts, network operators cannot rely on actual end-users to report their subjective quality of experience(QoE). Hence, automated and objective techniques that provide real-time or online VVoIP QoE estimates are vital. Objective techniques developed to-date estimate VVoIP QoE by performing frame-to-frame peak-signal-to-noise ratio(PSNR) comparisons of the original video sequence and the reconstructed video sequence obtained from the sender-side and receiver-side, respectively. Since processing such video sequences is time consuming and computationally intensive, existing objective techniques cannot provide online VVoIP QoE. In this paper, we present a novel framework that can provide online estimates of VVoIP QoE on network paths without end-user involvement and without requiring any video sequences. The framework features the "GAP-model", which is an offline model of QoE expressed as a function of measurable network factors such as bandwidth, delay, jitter, and loss. Using the GAP-model, our online framework can produce VVoIP QoE estimates in terms of "Good", "Acceptable", or "Poor"(GAP) grades of perceptual quality solely from the online measured network conditions.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.40 no.6
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• pp.124-131
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• 2003

In this paper, we propose a Progressive scalable video coding algorithm using frequency weighting in the DCT domain. Since the human visual system (HVS) can be modeled as a nonlinear point transformation, called the modulation transfer function (MTF), we tan use the frequency weighting matrix to enhance the video image quality. We change this frequency weighting matrix into the frequency shift matrix to apply to the bit-plane coding method for the fine granular scalable (FGS) video coding We also define a new error metric JNDE (just noticeable difference) to measure the perceptual image quality in terms of human vision.

• Journal of Korea Society of Industrial Information Systems
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• v.11 no.3
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• pp.69-81
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• 2006

In this paper, an adaptive algorithm is proposed in streaming MPEG-4 contents with fluctuating resource amount such as throughput of network conditions. In the area of adaptive streaming issue, a lot of researches have been made on how to represent encoded media(such as video) bitstream in scalable way. By contrast, MPEG-4 supports object-based multimedia content which is composed of various types of media streams such as audio, video, image and other graphical elements. Thus, it can be more effective to provide individual media streams in scalable way for streaming object-based content to heterogeneous environment. The proposed method provides the multiple media streams corresponding to an object with different qualities and bit rate in order to support object based scalability to the MPEG-4 content. In addition, an optimal selection of the multiple streams for each object to meet a given constraint is proposed. The selection process is adopted a multiple choice knapsack problem with multi-step selection for the MPEG-4 objects with different scalability levels. The proposed algorithm enforces the optimal selection process to maintain the perceptual qualities of more important objects at the best effort. The experimental results show that the set of selected media stream for presenting objects meets a current transmission condition with more high perceptual quality.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2014.06a
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• pp.203-205
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• 2014

본 논문에서는 HEVC 기반 비디오 부호화에 있어 CTU 단위의 시각 민감도에 따라 CTU 별로 QP 를 조절하여 주관적 화질을 향상시키는 방법을 제안한다. 시각 민감도를 측정하는 방법으로서 화소 영역에서의 최소가지차(JND, just noticeable distortion)를 계산하여 이용하였고, 이를 HM 12.0 참조 소프트웨어에서 이용되는 $R-{\lambda}$ 모델 기반의 율 제어 모듈에 결합하여 시각 민감도에 따라 QP 를 제어할 수 있도록 하였다. 시각 민감도가 큰 영상의 영역에 대해서는 상대적으로 작은 QP 값을, 시각민감도가 작은 영역에 대해서는 큰 QP 값을 양자화 과정에 적용함으로써, 시각 민감도가 작은 영역에 대해서는 사용 비트양을 절약하고, 절약된 비트를 상대적으로 시각 민감도가 큰 영역을 위해 사용함으로써 비디오의 주관적 화질을 향상시킬 수 있었다. 뿐만 아니라 이를 하드웨어에 적용 가능하게 하기 위해 HM 12.0 기반 하드웨어 구현을 위한 소프트웨어 플랫폼에 구현하여 실험한 결과, $R-{\lambda}$ 모델 율 제어 알고리즘으로 율 제어 하여 부호화 한 경우 Y-PSPNR(peak signal to perceptual noise ratio)에 대한 BD-rate 는 평균 9.4%의 이득이 있었음을 확인하였다.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.4
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• pp.110-122
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• 2014

As multimedia technologies develop, three-dimensional (3D) technologies are attracting increasing attention from researchers. In particular, video quality assessment (VQA) has become a critical issue in stereoscopic image/video processing applications. Furthermore, a human visual system (HVS) could play an important role in the measurement of stereoscopic video quality, yet existing VQA methods have done little to develop a HVS for stereoscopic video. We seek to amend this by proposing a 3D visual attention (3DVA) model which simulates the HVS for stereoscopic video by combining multiple perceptual stimuli such as depth, motion, color, intensity, and orientation contrast. We utilize this 3DVA model for pooling on significant regions of very poor video quality, and we propose no-reference (NR) stereoscopic VQA (SVQA) method. We validated the proposed SVQA method using subjective test scores from our results and those reported by others. Our approach yields high correlation with the measured mean opinion score (MOS) as well as consistent performance in asymmetric coding conditions. Additionally, the 3DVA model is used to extract information for the region-of-interest (ROI). Subjective evaluations of the extracted ROI indicate that the 3DVA-based ROI extraction outperforms the other compared extraction methods using spatial or/and temporal terms.

• ETRI Journal
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• v.39 no.3
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• pp.301-309
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• 2017

In this paper, we propose a parallelization method for a High Efficiency Video Coding (HEVC) deblocking filter with transform unit (TU) split information. HEVC employs a deblocking filter to boost perceptual quality and coding efficiency. The deblocking filter was designed for data-level parallelism. In this paper, we demonstrate a method of distributing equal workloads to all cores or threads by anticipating the deblocking filter complexity based on the coding unit depth and TU split information. We determined that the average time saving of our proposed deblocking filter parallelization method has a speed-up factor that is 2% better than that of the uniformly distributed parallel deblocking filter, and 6% better than that of coding tree unit row distribution parallelism. In addition, we determined that the speed-up factor of our proposed deblocking filter parallelization method, in terms of percentage run-time, is up to 3.1 compared to the run-time of the HEVC test model 12.0 deblocking filter with a sequential implementation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.2C
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• pp.139-147
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• 2006

This paper presents an overlay video multicast system over the Internet. The proposed system consists of two parts, i.e. overlay multicast tree suitable for the real-time video delivery and H.263+ rate control adaptive to overlay multicast tree. Overlay multicast tree is constructed to minimize the average time delay of members, and H.263+ rate control pursues a tradeoff between spatial and temporal qualities to enhance the human visual perceptual quality. Two systems are integrated and tested over the real Internet. And experimental results are provided to show the performance of the proposed system.

• Journal of Broadcast Engineering
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• v.12 no.1 s.34
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• pp.41-52
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• 2007

The 3DTV services can be seen as a general case of the multi-view video that has been receiving a significant attention lately. However, the key factors that influence the success of 3DTV are the availability of content, the ease of use, the quality of contents, and the reduction of cost. This paper deals primarily with the perceptual improvement in image quality, especially based on human factors. An optimal asymmetrical coding method for binocular and multi-view images is presented. The quantitative value of asymmetrical rate to maintain optimized subjective image quality is explored. Also we analyze how edges of 2D images affect on 3D perceptions and propose an edge-preserving algorithm to perform perceptual improvements. Experimental results demonstrate that the proposed algorithm enhances subjective image quality much better than conventional methods.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.2
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• pp.790-809
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• 2019

The design of an efficient scaler to enhance the edge data is one of the most important issues in video signal applications, because the perceptual quality of the processed image is sensitively affected by the degradation of edge data. Various conventional scaling schemes have been proposed to enhance the edge data. In this paper, we propose an efficient scaling algorithm for this purpose. The proposed method is based on the discrete cosine transform-based interpolation filter (DCT-IF) because it outperforms other scaling algorithms in various configurations. The proposed DCT-IF incorporates weighting parameters that are optimized for training data. Simulation results show that the quality of the resized image produced by the proposed DCT-IF is much higher than that of those produced by the conventional schemes, although the proposed DCT-IF is more complex than other conventional scaling algorithms.