• Proceedings of the IEEK Conference
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• 2000.11d
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• pp.53-56
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• 2000

In progressive image coding, if object region that have main contents in image are transmitted prior to the remained region, this method will be very useful. In this paper, the progressive image coding based on SPIHT using object region transmission method by priority is proposed. First, an original image is transformed by wavelet. Median filtering is used about wavelet transformed coefficient region for extracting object region. This extracted object region encoded by SPIHT. Then encoded object region are transmitted in advance of the remained region. This method is good to a conventional progressive image coding about entire original image. Experimental results show that the proposed method can be very effectively used for image coding applications such as internet retrieval and database searching system.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.6
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• pp.82-91
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• 1996

In this paper, an image coding technique using fractal interpolation is proposed. Similar to the conventional methods, an image is partitioned into blocks and each block is coded independently. However, an interpolation point is ahsared by its neighboring blocks. This means that each block can use all its interpolation points with minimal increase of new data. For a simple implementation, triangular blocks are used instead of square blocks and new coefficients are difined. Data obtained in the encoding process hav estatistical characteristics suitable sfor entropy coding, an dthus arithmetic coding is perfomred for improving the compression efficiency. The results of the proposed coder in comparison with those of a conventional coder show that the interpolation method reduces block effect caused by a memoryless block coder, especially at low bit rates. This improvement is due to sharing of information between adjacent blocks. Moreover, th enumber of iteration required in ecoding process is reduced since more information is used to decode each block.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.11
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• pp.44-52
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• 1996

This paper proposes a KLT-CVQ scheme using PCNN to improbe the quality of the reconstructed images at a given bit rate. By using the PCNN and classified vector quantization, we exploit the high energy compaction and compelte decorrelation capbilities of the KLT, and the pdf (probability density function) shape and space-filling advantages of the vQ to improve the performance of the proposed hybrid coding technique. In order to preserve the preceptual fetures such as the edge components in the reconstructed images, we classified the input image blocks according to the texture energy measures of the local statistics and vector-coded them adaptively, and thereby reduces the possible edge degradation in the reconstructed images. The results of the computer simulations show that the performance of the proposed KLT-CVQ is higher than that of the KLT-CSQ or the DCT-CVQ in the quality of the reconstructed images at a given bit rate.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.343-346
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• 2005

In this study, a basic concept of wavelet encoding and its advantages over Fourier based phase encoding application. Wavelet encoding has been proposed as an alternative way to Fourier based phase encoding in magnetic resonance imaging. In wavelet encoding, the RF pulse is designed to generate wavelet-shaped excitation profile of spins. From the resulting echo signals, the wavelet transform coefficients of spin distribution are acquired and an original spin density is reconstructed from wavelet expansion. Wavelet encoding has several advantages over phase encoding. By minimizing redundancy of the data acquisition in a dynamic series of images, we can avoid some encoding steps without serious loss of quality in reconstructed image. This strategy may be regarded as data compression during imaging. Although there are some limitations in wavelet encoding, it is a promising scheme in a dynamic imaging.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.963-966
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• 2005

Previous works related to texture coordinate coding of the three-dimensional(3-D) mesh models employed the same predictor as the geometry coder. However, discontinuities in the texture coordinates cause unreasonable prediction. Especially, discontinuities become more serious for the 3-D mesh model with a non-atlas texture image. In this paper, we propose a new coding scheme to remove discontinuities in the texture coordinates by reallocating texture segments according to a coding order. Experiment results show that the proposed coding scheme outperforms the MPEG-4 3DMC standard in terms of compression efficiency. The proposed scheme not only overcome the discontinuity problem by regenerating a texture image, but also improve coding efficiency of texture coordinate compression.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2008.11a
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• pp.85-88
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• 2008

예비 슬라이스(Redundant picture)는 에러가 발생하기 쉬운 환경에서 비디오가 전송될 때 에러를 보상하기 위한 H.264/AVC 부호화 표준의 도구들 중에 하나이다. 본 논문에서는 예비 슬라이스의 삽입으로 인해 발생하는 오버헤드 비트와 손실률을 고려한 LA-RDO(Loss-aware rate-distortion optimization) 모델을 제시하며 제안하는 모델에 기초해서 예비 슬라이스의 삽입 여부를 결정한다. 실험결과는 제안하는 방법이 참조 소프트웨어(JM: Joint Model)에 있는 HRP(Hierarchical redundant picture)와 비교했을 때 평균 0.5dB의 PSNR이 증가함을 보였다. 특별히 낮은 비트율에서 상대적으로 높은 성능을 보이므로 비디오 화상 회의와 같이 낮은 비트의 영상을 요구하는 무선 전송 환경에 적합할 것으로 보인다.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.693-696
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• 2001

이동 통신 채널과 같이 에러 발생율이 높은 환경에서 부호화된 비디오 스트림 전송시 발생된 에러는 비디오 화질에 큰 영향을 준다. 본 논문에서 현재 널리 사용되고 있는 H.263의 복호화기에서 전송도중 에러가 발생했을 경우 추가적인 데이터 스트림의 삽입 없이 효율적으로 에러를 은닉할 수 있는 기법에 관하여 제안하였다. 특히 인터프레임 영상에서 손상되거나 손실된 움직임벡터에 대해 시간영역에서 관계가 깊은 이전 프레임에서 손실블록(매크로블록)과 같은 위치에 있는 블록의 움직임벡터와 현재 프레임에서 손실블록과 인접한 블록들의 움직임벡터 정보를 이용하여 손실 블록의 후보 움직임벡터를 구하게된다. 이러한 후보 움직임 벡터를 이용하여 통일한 움직임 벡터를 갖는 영역을 찾아 손실 블록이 어떤 움직임 영역에 속하는 지를 판단하여 손실된 블록을 복원하는 방법을 제안한다.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.847-850
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• 1998

An adaptive block DCT coding scheme is implemented with the same average distortion designated for each block. In this paper, a new implementation of the Discrete Cosine Tranform(DCT) for image is described. Practical system application is attained by maintaining a balance between complexity of implementation and performance. ADCT sub-blocks are sorted into mean according to level of image activity, measured by mean within each sub-block. Excellent performance is demonstrated in terms of PSNR of original and reconstructed images.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.143-146
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• 1998

A new stereoscopic codec. structure using MPEG-2 multiview profile is presented in this paper. In the suggested codec., the left image is coded with motion estimation in the base layerand the right image is coded with disparity estimation in the enhancement layer. Since it is possible to calculate rough motion of the right image sequence with disparity and motion of the left image sequence, motion compensation of the enhancement layer is performed without motion estimation. Since the proposed codec. does not perform motion estimation in the enhancement layer encoding, it is simple and reduces the encoding time. We compared the PSNR of encoded image with three different structured codec., and the experimental results show that suggested codec. has comparable with other codecs.

• Proceedings of the IEEK Conference
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• 2000.06c
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• pp.113-116
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• 2000

In this paper, we present new scheme for image coding which efficiently use the relationship between the properties of spatial image and its wavelet transform. Firstly an original image is decomposed into several layers by the wavelet transform, and simultaneously decomposed into 2$\^$n/ ${\times}$ 2$\^$n/ blocks. Each block is classified into 3 regions according to their property, i.e., low activity region(LAR), midrange activity region(MAR), high activity region(HAR). Secondly we are applied texture modeling technique to LAR, MAR and HAR are encoded by Stack-Run coding technique. Finally our scheme Is superior to the Zerotree method in both reconstructed image Quality and transmitted bit rates.