• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.1730-1733
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• 1997

In this paper, a realization of a subband coding with TMS320C80 is studied. TMS320C80 is a multi-media processor specially designed for an image process. A main topic of this paper, as mentioned above, is an application of TMS320C80 to subband coding. Subband coding is the coding that devides full image to several subbands and encodes each subband with different coding methods. As using that methods, good image compression can be obtained. First above all, goal of this paper deals with TMS320C80 in coding still image and useds it in expending it's application to 3-D video coding.

• 대한전자공학회논문지
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• 제27권6호
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• pp.937-943
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• 1990

In this paper, a subband coding scheme using the human visual system(HVS) model for encoding monochrome images is proposed to produce perceptually higher quality images compared with the regular subband coding scheme. The proposed approach first transforms the intensity image to the density image by a point nonlinear transformation. A frequency band dexomposition of the density image is carried out by means of 2-D seaprable quadrature mirror filters, which split the density image spectrum into 16 equall rate subbands. Bits are allocated among the subbands to minimize the weighted mean squar error (WMSE) for differential pulse code modulation(DPCM) coding of the subbands. The weight for each subband is calculated from the modulation transfer function (MTF) of the HVS model at corresponding frequencies. The performances of the proposed approach are evaluated for 256 * 256 monochrome images at the bit rates of 0.5, 0.75 and 1.0 bita per pixel. Computer simulation results indicate that using the HVS model yields more pleasing reconstructed images than regular subband coding approach which does not use HVS model.

• 전자공학회논문지B
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• 제31B권4호
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• pp.88-96
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• 1994

In this paper, we propose a subband pyramid image coding scheme that uses ECVQ (ntropy Constrained Vector Quantizer). In subband pyramid image coding, each subband can be encoded with a coder matched to the statistics of that particular subband, and available versions of the original image at different resolution are easily obtained. ECVQ, aiming at the minimization of the distortion for a fixed entropy of the quantizer output, is well combined with the subband pyramid image coding which yields high compression ratio and good image quality. The optimum bit allocation to each subbands corresponds to the points where the individual distortion rate curves are of particular slope, weighted to the number of samples in that subband, in designing ECVQ.

• 한국통신학회논문지
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• 제22권11호
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• pp.2375-2380
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• 1997

The need for developing effective coding techniques for various multimedia services is increasing in order to meet the demand for image data. In this paper, a zeroblock coding algorithm is proposed for progressive transmission of images. The zeroblock coding algorithm is constructed as an embedded coding so that the encoding and decoding process can be terminated at any point and allowing reasonable image quality. Some features of zeroblock coding algorithm are 1) coding of subband images by prediction of the insignificance of blocks across subband leels, 2) aset of sate transition rules for representing the significance map of blocks, and 3) block coding by vector quantization using a multiband codebook consisting of several subcodebooks dedicated for each subband at a given threshold.

• 전자공학회논문지S
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• 제35S권2호
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• pp.97-105
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• 1998

Subband/DCT coding has been introduced in order to transmit images of various resultions using one given image-codec, for nowadays there are various grades of quality in visual communication services. However, subband/DCT results in the increawse of multiplication number and memory size. In order to resolve this problem, we propose block-based subband/DCT coding in this paper. In block-based subband/DCT, the number of multiplications is not only reduced because we combine subband decomposistion with DCT, but the size of memory is also reduced because images can be parallel-processed block by block. We show that the number of multiplications is reduced, by analyzing the property ofblock-based subband/DCT matrix mathematically, and examine the performance of proposed coder, which adopts JPEG as backhand-coder after block-based subband/DCT.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 하계종합학술대회논문집
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• pp.655-658
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• 1998

This paper proposes a moving image compression algorithm using subband coding that divides and processes the differential image of each moving image frame into subband frequency. This method decomposes the original image with each subband and performs DCT. The moving blocks are detected from each of wubband using threshold value which is select from the variance of difference between frames. then they are performed SBDCT and huffman coding in order to reduce the data. As the result of simulation, we confirmed that this method improved the blocking effect of reconstructed image in low bit rate.

• 한국통신학회논문지
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• 제17권9호
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• pp.927-938
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• 1992

1차원 대역 부호화 방식에서 신호를 두개의 주파수 대역으로 나누고 다시 복원하기 위해서 송수신단에서 쌍으로된 QMF를 사용한다. 본 논문에서는 대역 부호화 방식을 위한 또다른 1차원 복원 여파기를 소개하고, 에너지 분포를 고려한 분류 양자화 기법을 사용한 16대역 영상의 부호화 방법을 기술하였다. 컴퓨터 시뮬레이션 결과 이 방법은 기존의 벡터 양자화 방법과 비교할때 비슷한 주관적 화질에서 $20{\sim}30%$정도의 데이터 압축율을 얻을 수 있음을 보였다.

• 한국산업정보학회논문지
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• 제6권1호
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• pp.39-47
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• 2001

A blocked zerotree coding algorithm for compression of subband image is proposed. Significance of blocks with respect to a certain threshold are coded with a set of transition rules for the significance of blocks. Significant blocks are quantized by vector quantization. The basic idea for this coding approach are: 1) Subband images are coded by blocks, 2) Important blocks based on the significance of blocks are coded and quantized, 3) Multiband codebook which is composed of sub-codebooks dedicated for each threshold and subband level is adapted to produce good reproduction vectors for vector quantization. The compression results are similar to Shapiro's zerotree coding even though ours are obtained without entropy coding of bit streams from blocked zerotree encoder. If an entropy coding is applied to the bitstream, PSNR will be improved.

• 한국전자통신학회논문지
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• 제5권3호
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• pp.256-261
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• 2010

본 연구에서는 신경회로망의 일종인 GRNN을 이용하여 동영상 대역분할 부호화에 적용하고자 하는 새로운 비선형 움직임 예측기를 제안하였다. 제안된 비선형 예측기의 성능은 가장 일반적으로 많이 사용되는 블록매칭 알고리즘과 비교하였다. 결과적으로 제안된 비선형 움직임 예측기는 블록매칭 알고리즘보다 2-3dB 성능이 우수함을 알 수 있었다. 특히, 제안된 예측기는 클러스터링 과정과 잡음 신호를 둔화시키는 기능이 있어서 원영상의 에지를 잘 보존하는 장점이 있음을 알 수 있다. 이러한 결과는 인간의 시각적 특성에 중요하며 동영상의 대역분할 부호화에서도 우수한 특성을 나타낸다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 하계종합학술대회논문집
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• pp.677-680
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• 1998

In this paper, we proposed a lwo bit rate subband coding with adaptive vector quantization using the correlation between motion vector and block energy in subband. In this method, the difference between the input signal and the motion compensated interframe prediction signal is decomposed into several narrow bands using quadrature mirror filter (QMF) structure. The subband signals are then quantized by adaptive vector quantizers. In the codebook generating process, each classified region closer to the block value in the same region after the classification of region by the magnitude of motion vector and the variance values of subband block. Because codebook is genrated considering energy distribution of each region classified by motion vector and variance of subband block, this technique gives a very good visual quality at low bit rate coding.