• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2012.11a
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• pp.180-183
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• 2012

본 논문에서는 고속 움직임 예측(Fast Motion Estimation)방법의 일종인 다단계 연속 제거 알고리즘(MSEA : Multi-level Successive Elimination Algorithm)에 움직임의 역동성 정도를 고려하여 적응적인 가중치를 적용하는 방안에 대해 제안하였다. 움직임을 예측하는 과정에서 영상의 화질 손상이 발생하는 방식(Lossy Motion Estimation Algorithm)에서 모든 단위 블록(Macro Block)에 고정된 가중치만을 적용하는 기존의 방식과 달리 주위 블록의 움직임 벡터(Motion Vector)를 통해 움직임의 정도를 가정하여 적응적인 가중치를 적용함으로써 화질 손상을 줄이는 것이 목적이다. 제안하는 알고리즘으로 설계한 실험으로부터 MSEA에 적응적 가중치를 사용할 경우의 효율성을 확인하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.8B
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• pp.1518-1531
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• 1999

The reconstructed images from highly compressed MPEG or H.263 data have noticeable image degradations, such as blocking artifacts near the block boundaries, corner outliers at cross points of blocks, and ringing noise near image edges, because the MPEG or H.263 quantizes the transformed coefficients of 8$\times$8 pixel blocks. A post-processing algorithm has been proposed by authors to reduce quantization effects, such as blocking artifacts, corner outliers, and ringing noise, in MPEG-decompressed images. Our signal-adaptive post-processing algorithm reduces the quantization effects adaptively by using both spatial frequency and temporal information extracted from the compressed data. The blocking artifacts are reduced by one-dimensional (1-D) horizontal and vertical low pass filtering (LPF), and the ringing noise is reduced by two-dimensional (2-D) signal-adaptive filtering (SAF). A comparison study of the subjective quality evaluation using modified single stimulus method (MSSM), the objective quality evaluation (PSNR) and the computation complexity analysis between the signal-adaptive post-processing algorithm and the MPEG-4 VM (Verification Model) post-processing algorithm is performed by computer simulation with several MPEG-4 image sequences. According to the comparison study, the subjective image qualities of both algorithms are similar, whereas the PSNR and the comparison complexity analysis of the signal-adaptive post-processing algorithm shows better performance than the VM post-processing algorithm.

• The Journal of the Korea Contents Association
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• v.9 no.4
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• pp.27-33
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• 2009

Selection of the Lagrangian multiplier is a key factor to determine the performance of Rate-Distortion Optimization (RDO) in video coding. JM, reference S/W of H.264, employs only one RDO model for all macroblock. However, since the characteristics of macroblocks are different, RDO model adaptive to their characteristics can give some performance improvement. In this paper, we propose an RDO algorithm adaptive to characteristics of macroblocks. We empirically obtain the optimal Lagrangian multipliers considering characteristics of macroblocks. For performance evaluation, the proposed method is applied to JM10.2 and, as a result, we have PSNR gain of 0.2dB on average.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.8C
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• pp.598-604
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• 2008

The hold-type display panel such as a liquid crystal displays(LCD) has problem of motion blur. The problem can be improved by a Frame Rate-up Conversion(FRC) using a frame interpolation. We propose a Motion Estimation(ME) by using adaptively expanded block based on frame difference for PRC. The proposed method is executed using an adaptively expanded block in order to get more accurate motion vector. By using frame difference, we can reduce complexity more significantly than conventional methods. We use quantitative analysis in order to evaluate experimental results. The results show that the proposed method has better performance and lower complexity than conventional methods.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.5C
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• pp.487-495
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• 2007

When error occurs during the network transmission of the image, the quality of the restored image is very serious. Therefore to maintain the received image quality, the error concealment technique is necessary. This paper presents an efficient spatial error concealment method using adaptive edge-oriented interpolation. It deals with errors on slice level. The proposed method uses boundary matching method having 2-step processes. We divide error block into external and internal region, adaptively restore each region. Because this method use overall as well as local edge characteristics, it preserves edge continuity and texture feature. The proposed technique reduces the complexity and provide better reconstruction quality for damaged images than the previous methods.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.6C
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• pp.465-474
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• 2005

In this paper, a directional reconstruction of lost block in image over noisy channel is presented. DCT coefficients or pixel values in the lost blocks are recovered by using the linear interpolation with available neighboring blocks that are adaptively selected by the directional measure that are composed of the DDC (Difference of DC opposite blocks)and SAC(Similarity of AC opposite blocks) between opposite blocks around lost blocks. The proposed directional recovery method is effective for the strong edge and texture regions because we do not make use of the fixed 4-neighboring blocks but exploit the varying neighboring blocks adaptively by the directional information in the local image. In this paper, we describe the novel directional measure(CDS: Combination of DDC and SAC) composed of the DDC and the SAC and select the usable block to recover the lost block with the directional measure. The proposed method shows about 0.6dB PSNR improvement in average compared to the conventional methods.

• Journal of Broadcast Engineering
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• v.17 no.6
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• pp.1048-1060
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• 2012

In this paper, an adaptive temporal and spatial filter (ATSF) based on mean square error (MSE) estimation is proposed. ATSF is a block based de-noising algorithm. Each noisy block is selectively filtered by a temporal filter or a spatial filter. Multi-hypothesis motion compensated filter (MHMCF) and bilateral filter are chosen as the temporal filter and the spatial filter, respectively. Although there is no original video, we mathematically derivate a formular to estimate the real MSE between a block de-noised by MHMCF and its original block and a linear model is proposed to estimate the real MSE between a block de-noised by bilateral filter and its original block. Finally, each noisy block is processed by the filter with a smaller estimated MSE. Simulation results show that our proposed algorithm achieves substantial improvements in terms of both visual quality and PSNR as compared with the conventional de-noising algorithms.

• Journal of the Korea Society of Computer and Information
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• v.16 no.4
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• pp.73-81
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• 2011

In this paper, an improved block-based background modeling technique using adaptive parameter estimation that judiciously adjusts the number of model histograms at each frame sequence is proposed. The conventional block-based background modeling method has a fixed number of background model histograms, resulting to false negatives when the image sequence has either rapid illumination changes or swiftly moving objects, and to false positives with motionless objects. In addition, the number of optimal model histogram that changes each type of input image must have found manually. We demonstrate the proposed method is promising through representative performance evaluations including the background modeling in an elevator environment that may have situations with rapid illumination changes, moving objects, and motionless objects.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2006.11a
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• pp.121-124
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• 2006

본 논문에서는 영상 압축에 있어서 사용되는 새로운 고속 움직임 추정 기법에 대해 소개한다. 전역 탐색 블록 정합 알고리즘(FSBMA)은 최상의 PSNR을 갖는 화질로 움직임 벡터를 추정할 수 있지만 높은 계산량으로 인하여 실시간 구현에 부적합하다는 단점을 가지고 있다. 그러므로 계산량을 낮추면서 유사한 화질을 유지할 수 있는 많은 고속 탐색 기법들이 제안되어 왔다. 본 논문에서는 기존의 잘 알려진 고속 블록 정합 알고리즘을 수정 보완한 새로운 알고리즘을 제안한다. 제안한 방법에서는 움직임 추정에서의 고속 블록 정합 알고리즘에 있어 변형된 다이아몬드(Diamond) 탐색 기법을 이용하여 영상이 갖는 서로 다른 움직임 패턴에 대해 움직임의 방향성에 따라 적응적으로 탐색 방향과 패턴을 달리하면서 움직임을 예측하여 다이아몬드(Diamond)탐색 알고리즘과 유사한 화질을 유지하면서 보다 적은 계산량을 가지고 움직임 벡터를 추정학 수 있다. 또한 이를 PMVFAST(Predictive Motion Vector Field Adaptive Search Technique)와 결합함으로서 보다 좋은 화질을 가질 수 있다.

• Annual Conference of KIPS
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• 2001.10a
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• pp.813-816
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• 2001

본 논문에서 제안한 알고리듬은 동영상의 한 프레임내에서 계산할 화소를 적응적으로 샘플링하여 전체 계산량을 감소시키면서도, 우수한 성능을 나타낸다. 동영상의 움직임 추정에 있어서, 전역 탐색 블록 정합은 최적의 성능을 나타내지만, 많은 계산량을 갖는 단점이 있기 때문에 계산량을 줄이기 위한 많은 알고리듬이 발표되었다. 본 알고리듬은 한 프레임내에서 영상이 복잡한 부분에서는 많은 수의 화소를 정합에 이용하며, 단순한 부분에서는 적은 수의 화소를 샘플링 하여 보다 적은 계산량으로 움직임 벡터를 산출한다. 제안된 알고리듬은 전역 탐색 블록 정합 알고리듬에 대해서 연산량을 31.52%로 줄였으며, 97.76%의 PSNR 을 보여주었다. 이는 종래의 부분 탐색 알고리듬들에 비해 뒤지지 않는 성능을 나타낸다.