• Proceedings of the Korean Information Science Society Conference
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• 2006.10a
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• pp.153-157
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• 2006

기존의 탐색 알고리즘은 탐색 창 내의 원점에서 탐색을 시작한다. 하지만 영상은 일정한 방향으로 규칙적으로 움직이는 것이 많기 때문에 Frame$_t$ 의 움직임 벡터(MV)가 Frame$_{t-1}$의 움직임 벡터와 같을 가능성이 크다. 이를 참고하여 본 논문에서는 시작점을 원점뿐만 아니라 Frame$_{t-1}$의 MV까지도 예측 시작점으로 선택하여 탐색의 시작점을 다양화 하였다. 실험 결과 탐색 시작점을 다양화 함으로써 full search를 제외한 diamond search, hexagonal search, 4 step search등 기존의 탐색 알고리즘보다 30$\sim$80% 더 작은 SAD값을 구할 수 있었다.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.12
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• pp.110-119
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• 1996

A novel high speed VLSI architecture and its VLSI realization methodologies for a motion estimation processor based on full search block matching algorithm are presentd. The presented architecture is designed in order to be suitable for highly parallel and pipelined processing with identical PE's and adjustable in performance and hardware amount according to various application areas. Also, the throughput is maximized by enhancing PE utilization up to 100% and the chip pin count is reduced by reusing image data with embedded image memories. Also, the uniform and identical data processing structure of PE's eases VLSI implementation and the clock rate of external I/O data can be made slower compared to internal clock rate to resolve I/O bottleneck problem. The logic and spice simulation results of the proposed architecture are presented. The performances of the proposed architecture are evaluated and compared with other architectures. Finally, the chip layout is shown.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.1
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• pp.8-13
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• 2008

The high peak-to-average power ratio(PAPR) of the transmitted signals is one of the major drawbacks of the orthogonal frequency division multiplexing(OFDM). The partial transmit sequences(PTS) technique can improve the PAPR statistics of the OFDM signals. However, in the PTS technique, the computational complexity to select phase weighting factors increases exponentially with the number of sub-blocks. In this paper, a search algorithm that has no limit on the values of phase weighting factors and requires no additional operations for the search is presented. To evaluate the performance, the proposed search algorithm is compared with the full search algorithm in terms of the complementary cumulative distribution function(CCDF) of the PAPR and the computational complexity. It is shown through simulations that the proposed technique can achieve significant reductions in the computational complexity with little performance degradation compared with the full search algorithm.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.39 no.5
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• pp.34-42
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• 2002

In this paper, we designed the VLSI array architecture for the high speed processing of the motion estimation used by block matching algorithm. We derived the one dimensional systolic array from the full search block matching algorithm. The data and control signals of the proposed systolic array are passed through adjacent processing element. So proposed architecture has temporal and spatial locality. The I/O ports exists only in the first and last processing elements of the array. This architecture has low pin counts and modular expandability. So the proposed array architecture can be cascaded for different block size and search range.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.2
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• pp.338-347
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• 2005

In this paper, a decimation-in-time search direction algorithm for displacement prediction of moving object is proposed. The initialization of the proposed algorithm for moving direction prediction is performed by detecting moving objects at sequential frames and by obtaining a moving angle and a moving distance. A moving direction of the moving object at current frame is obtained by applying the decimation-in-time search direction mask. The decimation-in-tine search direction mask is that the moving object is detected by thinning out frames among the sequential frames, and the moving direction of the moving object is predicted by the search mask which is decided by obtaining the moving angle of the moving object in the 8 directions. to examine the propriety of the proposed algorithm, velocities of a driving car are measured and tracked, and to evaluate the efficiency, the proposed algorithm is compared to the full search algorithm. The evaluated results show that the number of displacement search times is reduced up to 91.8$\%$ on the average in the proposed algorithm, and the processing time of the tracking is 32.1ms on the average.

• Journal of Broadcast Engineering
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• v.18 no.5
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• pp.730-737
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• 2013

In this paper, Constrained One-Bit Transform (C1BT) based motion estimation using extension of matching error criterion is proposed. C1BT based motion estimation algorithm exploiting Number of Non-Matching Points (NNMP) instead of Sum of Absolute Differences (SAD) that used in the Full Search Algorithm (FSA) facilitates hardware implementation and significantly reduces computational complexity. However, the accuracy of motion estimation is decreased. To improve inaccurate motion estimation, this algorithm based motion estimation extending matching error criterion of C1BT is proposed in this paper. Experimental results show that proposed algorithm has better performance compared with the conventional algorithm in terms of Peak-Signal-to-Noise-Ratio (PSNR).

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2001.11b
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• pp.95-98
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• 2001

본 논문에서는 동영상 압축 방식에서 압축 효율을 증가시키는 움직임 벡터 추정 방식의 개선된 방법에 대해 제안한다. 움직임 벡터 추정 방식의 하나인 BMA(block matching algorithm) 중에 가장 좋은 성능을 보이는 FSA(full search algorithm)은 움직임의 정도를 예측하지 않고 모든 블록에 대해 고정적인 탐색 영역이 결정되어 있다. 이는 계산량을 상당히 크게 하는 원인이 된다. 제안된 방식은 블록 사이의 움직임이 유사한 특성을 이용하여 블록 단위의 동적인 탐색 영역을 결정하여 계산량을 효율적으로 줄이면서 FSA와 유사한 특성을 유지하게 된다.

• The KIPS Transactions:PartB
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• v.11B no.3
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• pp.327-336
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• 2004

For visual inspection system in real industrial environment, it is one of most important tasks to design fast and stable pattern matching algorithm. This paper presents an edge-based point correlation algorithm avoiding full search in visual inspection system. Conventional algorithms based on NGC(normalized gray-level correlation) have to overcome some difficulties for applying to automated inspection system in factory environment. First of all, NGC algorithms need high time complexity and thus high performance hardware to satisfy real-time process. In addition, lighting condition in realistic factory environments if not stable and therefore intensity variation from uncontrolled lights gives many roubles for applying directly NGC as pattern matching algorithm in this paper, we propose an algorithm to solve these problems from using thinned and binarized edge data and skipping full point search with edge-map analysis. A point correlation algorithm with the thinned edges is introduced with image pyramid technique to reduce the time complexity. Matching edges instead of using original gray-level pixel data overcomes NGC problems and pyramid of edges also provides fast and stable processing. All proposed methods are preyed from experiments using real images.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.1434-1437
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• 1987

We present a very simple algorithm for reducing the encoding (codebook search) complexity of vector quantization (VQ), exploiting some features of a vector currently being encoded. A proposed VQ of 16 (=$4{\times}4$) vector dimension and 256 codewords shows a slight performance degradation of about 0.1-0.9 dB, however, with only 16 or 32 among 256 codeword searches, i.e., with just 1/16 or 1/8 search complexity compared to a full-search VQ. And the proposed VQ scheme is also compared to and shown to be a bit superior to tree-search VQ with regard to their SNR performance and memory requirement.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1996.06a
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• pp.203-207
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• 1996

This paper describes a method for estimating motion vectors in a video sequence. In this method, we find motion vectors using the full search method from the training images and then, train the codebook of the neural networks vector quantizer using these motion vectors. A motion vector can be estimated using the codebook as a motion prediction region. The codewords in the codebook represent the motion vectors for the input image sequences. Since the codebook is used as the search region for estimating the motion vectors, search points and computation can be reduced compared with the full search block matching algorithm. Additionally, the information required to transmit the motion vectors can be reduced.