• Journal of the Korean Institute of Telematics and Electronics B
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• v.32B no.8
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• pp.1091-1098
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• 1995

This paper proposes an efficient noiseless encoding method of vector quantization(VQ) index using a dynamic index mapping. Using high interblock correlation, the proposed index mapper transforms an index into a new one with lower entropy. In order to achieve good performance with low computational complexity, we adopt 'the sum of differences in pixel values on the block boundaries' as the cost function for index mapping. Simulation results show that the proposed scheme reduces the average bitrate by 40 - 50 % in ordinary VQ system for image compression. In addition, it is shown that the proposed index mapping method can be also applied to mean-residual VQ system, which allows the reduction of bitrate for VQ index by 20 - 30 %(10 - 20 % reduction in total bitrate). Since the proposed scheme is one for noiseless encoding of VQ index, it provides the same quality of the reconstructed image as the conventional VQ system.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.4
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• pp.62-76
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• 1994

In this paper, a segmentation-based coding technique as applied to video sequences is proposed. A proposed method separates an image into contour and texture parts, then the visually-sensitive contour part is represented by chain codes and the visually-insensitive texture part is reconstructed by a representative motion vector of a region and mean of the segmented frame difference. It uses a change detector to find moving areas and adopts variable blocks to represent different motions correctly. For better quality of reconstructed images, the displaced frame difference between the original image and the motion compensated image reconstructed by the representative motion vector is segmented. Computer simulation with several video sequences shows that the proposed method gives better performance than the conventional ones in terms of the peak signal to noise ratio(PSNR) and compression ration.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06b
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• pp.400-402
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• 2006

임베디드 시스템에서의 코드 압축은 효율성 제고를 위한 필수적인 기법이다. ARM, MIPS등 많은 프로그램 코드에서 현재 시도되고 있으나 한계를 나타내고 있다. 특히, Arm Thumb 코드는 다른 코드 압축과 달리, 아직까지 15%-20%정도의 압축 효율을 보이고 있다. 본 논문은 다양한 값을 갖는 코드의 데이터이지만, 일정 부분에서 특정 값의 발생빈도가 높은 Thumb 코드의 분포를 분석, 그 특성을 활용하였다. 즉, 현재 압축하고자 하는 필드의 값을 코드의 앞부분과 비교해 나가면서, 유사도를 분석 및 압축하고, 거리 정보를 기록하는 방식의 거리 벡터 기법의 압축방법을 고안, 적용하였고, 그 결과 압축효율이 20-25%로 기존의 방법에 비하여 약 5%정도의 효율 향상을 가져 왔다.

• Proceedings of the IEEK Conference
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• 2004.08c
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• pp.477-481
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• 2004

High Quality CD, OAT audio requires that large amount of data. Currently, multi channel preference has been rapidly propagated among latest users. The MPEG(Moving Picture Expert Group) is provides data compression technology of sound and image system. The MPEG standard provides multi channel and 5.1 sounds, using the same audio algorithm as MPEG-l. And MPEG-2 audio is forward and backward compatible. The MDCT (Modified Discrete Cosine Transform) is a linear orthogonal lapped transform based on the idea of TDAC(Time Domain Aliasing Cancellation). In this paper, we proposed the micro-program type vector processor architecture a benefit in MDCT/IMDCT of MPEG-II AAC. And it's reduced operating coefficient by overlapped area to bind. To compare original algorithm with optimized algorithm that cosine coefficient reduced $0.5\%$multiply operating $0.098\%$ and add operating 80.58\%$. Algorithm test is used C-language then we designed hardware architecture of micro-programmed method that applied to optimized algorithm. This processor is 20MHz operation 5V.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.39 no.1
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• pp.32-39
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• 2002

Vector quantization for image compression needs expensive encoding time to find the closest codeword to the input vector. This paper proposes a search algorithm for fast vector quantization encoding. Firstly, we derive a robust condition based on the efficient topological structure of the codebook to dramatically eliminate unnecessary matching operations from the search procedure. Then, we Propose a fast search algorithm using the elimination condition. Simulation results show that with little preprocessing and memory cost, the encoding time of the proposed algorithm is reduced significantly while the encoding quality remains the same with respect to the full search algorithm. It is also found that the Proposed algorithm outperforms the existing search algorithms.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.46 no.2
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• pp.48-56
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• 2009

We propose a fast intra mode skip decision algorithm for H.264/AVC video encoding. Although newly added MB encoding algorithms based on various prediction methods increase compression ratio, they require a significant increase in the computational complexity because we calculate rate-distortion(RD) cost for all possible MB coding modes and then choose the best one. In this paper, we propose a fast mode decision algorithm based on an adaptive motion vector map(AMVM) method for H.264/AVC video encoding to reduce the processing time for the inter frame. We verify that the proposed algorithm generates generally good performances in PSNR, bit rates, and processing time.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1383-1386
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• 1997

Discrete cosine transform(DCT) is the most popular block transform coding in lossy mode. DCT is close to statistically optimal transform-the Karhunen Loeve transform. In this paper, a module for DCT encoder is made with TMS320C80 based on JPEG and MPEG, which are intermational standards for image compression. the DCT encoder consists of three parts-a transformer, a vector quantizer and an entropy encoder.

• Korean Journal of Geomatics
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• v.3 no.2
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• pp.141-148
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• 2004

This paper deals with the characteristics of strain pattern by using permanent GPS stations in Korea in terms of seismic activity and tectonics. Fourteen GPS stations involved in precise baseline vector solution and horizontal strain components were calculated using the differences of mean baseline from ten deily solutions during the time span of three years. The mean rate of maximum shear strain if 0.12 $\mu$/yr. The mean direction of principal axes of the compression is about $85^{\circ}$ N.

• Proceedings of the Korean Information Science Society Conference
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• 2000.10b
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• pp.529-531
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• 2000

본 논문은 Geometry Compression 분야에서 다뤄지는 압축기법 중 delta encoding 과정을 보완하여 좀 더 높은 압축률을 얻고자 하는 vertex position prediction 과정에 대한 내용으로 구성되어 있다. 이것은 triangle strip 형태의 입력을 받아서 그 vertex data 중 position 정보들간의 delta encoding 과정을 예측 기법을 이용한 encoding 과정으로 대체하여 Huffman encoding 과정에서의 symbol 개수를 줄여 압축률을 향상시키자는 개념에서 출발한다. triangle strip 생성 기법 중 greedy algorithm을 적용한 후, 기존의 parallelogram 방식과 이 논문에서 새로이 제안하는 방식을 비교하여 보다 나은 압축 방식을 제시하는 것이 이 논문의 목적이다. 이 논문에서 제시하는 방식을 실험한 결과, 기존의 예측 기법에 비해 2.4% 정도의 향상을 보여주고 있다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.12B
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• pp.2391-2400
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• 1999

Vector quantizer (VQ) is an efficient data compression technique for low bit rate applications. However, the major disadvantage of VQ is its encoding complexity which increases dramatically as the vector dimension and bit rate increase. Even though one can use a modified VQ to reduce the encoding complexity, it is nearly impossible to implement such a VQ at a high bit rate or for a large vector dimension because of the enormously large memory requirement for the codebook and the very large training sequence (TS) size. To overcome this difficulty, in this paper we propose a novel structurally constrained VQ for the high bit rate and the large vector dimension cases in order to obtain VQ-level performance. Furthermore, this VQ can be extended to the low bit rate applications. The proposed quantization scheme has a form of feed-forward adaptive quantizer with a short adaptation period. Hence, we call this quantization scheme sample-adaptive product quantizer (SAPQ). SAPQ can provide a 2 ~3dB improvement over the Lloyd-Max scalar quantizers.