• ETRI Journal
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• 제32권4호
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• pp.577-587
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• 2010

The layered coding structure of scalable video coding (SVC) with adaptive inter-layer prediction causes noticeable computational complexity increments when compared to existing video coding standards. To lighten the computational complexity of SVC, we present a fast algorithm to speed up the inter-mode decision process. The proposed algorithm terminates inter-mode decision early in the enhancement layers by estimating the rate-distortion (RD) cost from the macroblocks of the base layer and the enhancement layer in temporal, spatial, and inter-layer directions. Moreover, a search range decision algorithm is also proposed in this paper to further increase the motion estimation speed by using the motion vector information from temporal, spatial, or inter-layer domains. Simulation results show that the proposed algorithm can determine the best mode and provide more efficient total coding time saving with very slight RD performance degradation for spatial and quality scalabilities.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(4)
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• pp.211-214
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• 2001

This paper presents an efficient fast motion estimation algorithm and image segmentation method for low bit-rate coding. First, with region split information, the algorithm splits the image having homogeneous and semantic regions like face and semantic regions in image. Then, in these regions, We find the motion vector using adaptive search window adjustment. Additionally, with this new segment based fast motion estimation, we reduce blocking artifacts by intensively coding our interesting region(face or arm) in input image. The simulation results show the improvement in coding performance and image quality.

• 정보처리학회논문지B
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• 제9B권1호
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• pp.83-90
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• 2002

본 연구에서는 영상데이터의 효율적인 압축과 전송을 위하여 EZW(embedded Zerotree wavelet)의 개선된 방안을 제안하였다 즉, 하위의 비중요계수들을 중요계수의 종속부호화에 사용함으로써 부호화 효율을 높였으며, 계수를 검색할 때 하위검색으로 미리 부호화하여 부호화시간을 단축하였다. 제안된 알고리즘은 상응하는 아키텍쳐로 설계하였으며, 이의 시뮬레이션을 기존의 EZW방법과 비교한 결과, 약 1dB정도의 PSNR 성능의 개선이 있음을 확인하였다.

• 한국통신학회논문지
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• 제33권3C호
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• pp.234-239
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• 2008

For the efficient coding and transmission, the speech signal can be classified into three distinctive classes: voiced, unvoiced, and transition classes. At low bit rate coding below 4 kbit/s, conventional sinusoidal transform coders synthesize speech of high quality for the purely voiced and unvoiced classes, whereas not for the transition class. The transition class including plosive sound and abrupt voiced-onset has the lack of periodicity, thus it is often classified and synthesized as the unvoiced class. In this paper, the efficient algorithm for the transition class detection is proposed, which demonstrates superior detection performance not only for clean speech but for noisy speech. For the detected transition frame, phase information is transmitted instead of magnitude information for speech synthesis. From the listening test, it was shown that the proposed algorithm produces better speech quality than the conventional one.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 정기총회 및 추계학술대회 논문집 학회본부
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• pp.346-349
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• 1993

A method for image compression based on decomposition is presented. We design the efficient coding technique for upper band image signals. This coding technique with directive 1-D DPCM is based on the statistical properties of upper bands. Lower band image signals is encoded using 2-D DPCM. The directive 1-D DPCM is performed, scanning upper bands according to edge direction. And then the predicted error signals of upper band sis coded using B1 and Huffman code, and the predicted error signals of lower band is coded using Huffman code. The proposed system shows improved performance when compared with other existing methods with respect to peak signal to noise ratio(PSMR) and human visual system(HVS) properties.

• 전자공학회논문지B
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• 제31B권4호
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• pp.97-105
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• 1994

Transform image coding using DCT is proved to be efficient in the absence of channel error but its performance degrades rapidly over noisy channel. In this paper, in the case of appling bit selcetive error correction coding that protects some significant bits in a codeword, an efficient allocation method of imformation bits and additive redundancy bits used for quantization and error correction coding respectively under constant transmission bit rate is proposed, and its performance is analyzed. As a result, without increasing trasmission bit rate, PSNR can be improved up to 7~8 [dB] below bit error rate $10^2$ and the image without blocking effect caused by bit error resulted from channel noise can be recostructed.

• 전자공학회논문지S
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• 제34S권9호
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• pp.99-108
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• 1997

An efficient wavelet packet algorithm to find wavelet packet quickly is presented in this paper. The top-down method maximizing the transform coding gain that is obtained from the second moment of the band is used to divide the subbands into wavelet tree. The bit allocation for each band in the tree is performed in proportion to its variance. Bands are coded by the lossless coding algorithm called the bit plane run length coding(BPRLC) and uniform quantizer. The proposed algorithm is compared with of the single tree algorithim proposed by Ramchandran and Vetterli. To verify the efficiency of our algorithm, simulations are jperformed using several sets of images. The results show us that our method reduces the execution time by about forty percent of that required by the single tree method while maintaining the comparable reconstructed image qualities.

• Journal of applied mathematics & informatics
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• 제5권1호
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• pp.191-200
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• 1998

There are two types of composition systems for the Korean alphabet: a combined system and a composite system. This paper decribes an efficient coding method for both of these two types. Using this coding method with the combined system yields about 10.5% code-length savings per a Korean character while it yields about 45% savings with the composite system. In other words the coding method produces a better result(i.e. 34.5% better) with the composite system than with the combined system. The simulation has been performed on a MasPar machine having 64 processors. The results show that the combined system achieved a 45.851-fold speedup while the composite system achieved a 47.274-fold speedup.

• 한국통신학회논문지
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• 제33권10C호
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• pp.778-786
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• 2008

가장 최근에 표준화된 H.264 동영상 압축 부호화 기법에서는 많은 새로운 기술들을 적용하여 높은 부호화 성능을 보인다. 특히 최적의 인트라 예측 모드를 결정하기 위해 모든 예측 모드들에 대해 비트율 왜곡 최적(rate distortion optimization) 기법을 적용하기 때문에 많은 계산량을 필요로 한다. 본 논문에서는 분산을 이용하여 인트라 모드를 결정하고 영상의 edge들을 찾아내는 연산을 통해 블록의 방향성을 찾고 그 방향성을 이용하여 인트라 예측 모드 결정에 필요한 계산량을 감소시키는 효율적인 기법을 제안한다.

• IEIE Transactions on Smart Processing and Computing
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• 제3권3호
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• pp.118-127
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• 2014

This paper presents an efficient motion and disparity prediction method for multi-view video coding based on the high efficient video coding (HEVC) standard. The proposed method exploits inter-view candidates for effective prediction of the motion or disparity vector to be coded. The inter-view candidates include not only the motion vectors of adjacent views, but also global disparities across views. The motion vectors coded earlier in an adjacent view were found to be helpful in predicting the current motion vector to reduce the number of bits used in the motion vector information. In addition, the proposed disparity prediction using the global disparity method was found to be effective for interview predictions. A multi-view version based on HEVC was used to evaluate the proposed algorithm, and the proposed correspondence prediction method was implemented on a multi-view platform based on HEVC. The proposed algorithm yielded a coding gain of approximately 2.9% in a high efficiency configuration random access mode.