• Title/Summary/Keyword: Sub-pixel Search

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A Fast Search Algorithm for Sub-Pixel Motion Estimation (부화소 움직임 추정을 위한 고속 탐색 기법)

  • Park, Dong-Kyun;Jo, Seong-Hyeon;Cho, Hyo-Moon;Lee, Jong-Hwa
    • Proceedings of the KIEE Conference
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    • 2007.04a
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    • pp.26-28
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    • 2007
  • The motion estimation is the most important technique in the image compression of the video standards. In the case of next generation standards in the video codec as H.264, a high compression-efficiency can be also obtained by using a motion compensation. To obtain the accurate motion search, a motion estimation should be achieved up to 1/2 pixel and 1/4 pixel uiuts. To do this, the computational complexity is increased although the image compression rate is increased. Therefore, in this paper, we propose the advanced sub-pixel block matching algorithm to reduce the computational complexity by using a statistical characteristics of SAD(Sum of Absolute Difference). Generally, the probability of the minimum SAD values is high when searching point is in the distance 1 from the reference point. Thus, we reduced the searching area and then we can overcome the computational complexity problem. The main concept of proposed algorithm, which based on TSS(Three Step Search) method, first we find three minimum SAD points which is in integer distance unit, and then, in second step, the optimal point is in 1/2 pixel unit either between the most minimum SAD value point and the second minimum SAD point or between the most minimum SAD value point and the third minimum SAD point In third step, after finding the smallest SAD value between two SAD values on 1/2 pixel unit, the final optimized point is between the most minimum SAD value and the result value of the third step, in 1/2 pixel unit i.e., 1/4 pixel unit in totally. The conventional TSS method needs an eight.. search points in the sub-pixel steps in 1/2 pixel unit and also an eight search points in 1/4 pixel, to detect the optimal point. However, in proposed algorithm, only total five search points are needed. In the result. 23 % improvement of processing speed is obtained.

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Sub-Pixel Motion Estimation by Using Only integ-Pixel (정수-화소만을 이용한 1/4-화소 단위 고속 움직임 추정)

  • Cho, Hyo-Moon;Park, Dong-Kyun;Cho, Snag-Bock
    • Proceedings of the IEEK Conference
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    • 2007.07a
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    • pp.383-384
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    • 2007
  • In this paper, we propose the new and simple method for sub-pixel block search algorithm by only using integer-pixel for motion estimation and compensation. In many papers, the fast search block match algorithms based on TSS have been proposed. However, these methods could be achieved a little reduction of the computational complexity. All of searching points by 1/4-pixel have own predicted integer-pixel SAD array. Therefor, if we know initial nine SAD values by integer, which is on the searching area of the reference frame, then we can find optimal searching point by 1/4-pixel, directly.

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Fast Sub-pixel Search Control by using Neighbor Motion Vector in H.264 (H.264에서 주변 움직임 벡터를 이용한 고속 부 화소 탐색 제어 기법)

  • La, Byeong-Du;Eom, Min-Young;Choe, Yoon-Sik
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.44 no.3
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    • pp.16-22
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    • 2007
  • Motion Estimation time in the H.264 has a large portion of encoding time and must be improved for real time application. Most of proposed motion estimation algorithm including Sub-pixel search use the fast search algorithm to speed up motion estimation by targeting the performance of full search in the reference code. This paper proposes a novel fast sub-pixel search control algorithm for H.264 encoder by using neighbor motion vector after analyzing the encoded Motion vector of video sequence. In addition the horizontal/vertical searching method is proposed with the horizontal/vertical directionality of motion vector. And the evaluation is performed with the proposed algorithms and other reference algorithms.

A Fast Sub-pixel Motion Estimation Method for H.264 Video Compression (H.264 동영상 압축을 위한 부 화소 단위에서의 고속 움직임 추정 방법)

  • Lee, Yun-Hwa;Choi, Myung-Hoon;Shin, Hyun-Chul
    • Journal of KIISE:Software and Applications
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    • v.33 no.4
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    • pp.411-417
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    • 2006
  • Motion Estimation (ME) is an important part of video coding process and it takes the largest amount of computation in video compression. Half-pixel and quarter-pixel motion estimation can improve the video compression rate at the cost of higher computational complexity In this paper, we suggest a new efficient low-complexity algorithm for half-pixel and quarter pixel motion estimation. It is based on the experimental results that the sum of absolute differences(SAD) shows parabolic shape and thus can be approximated by using interpolation techniques. The sub-pixel motion vector is searched from the minimum SAD integer-pixel motion vector. The sub-pixel search direction is determined toward the neighboring pixel with the lowest SAD among 8 neighbors. Experimental results show that more than 20% reduction in computation time can be achieved without affecting the quality of video.

A Study of Sub-Pixel Detection for Hyperspectral Image Using Linear Spectral Unmixing Algorithm (Linear Spectral Unmixing 기법을 이용한 하이퍼스펙트럴 영상의 Sub-Pixel Detection에 관한 연구)

  • 김대성;조영욱;한동엽;김용일
    • Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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    • 2003.04a
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    • pp.161-166
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    • 2003
  • Hyperspectral imagery have high spectral resolution and provide the potential for more accurate and detailed information extraction than any other type of remotely sensed data. In this paper, the "Linear Spectral Unmixing" model which is one solution to overcome the limit of spatial resolution for remote sensing data was introduced and we applied the algorithm to hyperspectral image. The result was not good because of some problems such as image calibration and used endmembers. Therefore, we analyzed the cause and had a search for a solution.

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An Enhanced Search Algorithm for Fast Motion Estimation using Sub-Pixel (부화소 단위의 빠른 움직임 예측을 위한 개선된 탐색 알고리즘)

  • Kim, Dae-Gon;Yoo, Cheol-Jung
    • Journal of the Korea Society of Computer and Information
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    • v.16 no.12
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    • pp.103-112
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    • 2011
  • Motion estimation (ME) is regarded as an important component in a video encoding process, because it consumes a large computation complexity. H.264/AVC requires additional computation overheads for fractional search and interpolation. This causes a problem that computational complexity is increased. In Motion estimation, SATD(Sum of Transform Difference) has the characteristics of a parabolic based on the minimum point. In this paper, we propose new prediction algorithm to reduce search point in motion estimation by sub-pixel interpolation characteristics. The proposed algorithm reduces the time of encoding process by decreasing computational complexity. Experimental results show that the proposed method reduces 20% of the computation complexity of motion estimation, while the degradation in video quality is negligible.

Adaptive Hierarchical Hexagon Search Using Spatio-temporal Motion Activity (시공간 움직임 활동도를 이용한 적응형 계층 육각 탐색)

  • Kwak, No-Yoon
    • Journal of Digital Contents Society
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    • v.8 no.4
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    • pp.441-449
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    • 2007
  • In video coding, motion estimation is a process to estimate the pixel of the current frame from the reference frame, which affects directly the predictive quality and the encoding time. This paper is related to AHHS(Adaptive Hierarchical Hexagon Search) using spatio-temporal motion activity for fast motion estimation. The proposed method defines the spatio-temporal motion activity of the current macroblock using the motion vectors of its spatio-temporally adjacent macroblocks, and then conventional AHS(Adaptive Hexagon Search) is performed if the spatio-temporal motion activity is lower, otherwise, hierarchical hexagon search is performed on a multi-layered hierarchical space constructed by multiple sub-images with low frequency in wavelet transform. In the paper, based on computer simulation results for multiple video sequences with different motion characteristics, the performance of the proposed method was analysed and assessed in terms of the predictive quality and the computational time. Experimental results indicate that the proposed method is both suitable for (quasi-) stationary and large motion searches. The proposed method could keep the merit of the adaptive hexagon search capable of fast estimating motion vectors and also adaptively reduce the local minima occurred in the video sequences with higher spatio-temporal motion activity.

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Optical Implementation of Improved IPA Model Using Hierarchical Recognition Algorithm (계층적 인식 알고리즘을 이용한 개선된 패턴상호연상모델의 광학적 구현)

  • 하재홍;김성용;김수중
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.31A no.7
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    • pp.55-62
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    • 1994
  • Interpattern association (IPA) model which the interconnection weight matrix(IWM) is constructed by the association between patterns is effective in similar pattern recognitions. But, if the number of reference patterns is increased, the ability of recognition is decreased. Using a hierarchical recognition algorithm which adopts the tree search strategy, we classified reference patterns into sub-groups by similarity. In IPA model, if input includes random noise we make it converge to reference pattern by means of input includes random noise we make it converge to reference pattern by means of increasing the number of pixels of prohibited state in IWM. In relation to reference patterns the pixel of prohibited state made partially prohibited state of no connected state using which is not included common and feature regions by each reference patterns.

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A Parametric Study of Displacement Measurements Using Digital Image Correlation Method

  • Ha, Kuen-Dong
    • Journal of Mechanical Science and Technology
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    • v.14 no.5
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    • pp.518-529
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    • 2000
  • A detailed and thorough parametric study of digital image correlation method is presented. A theoretical background and development of the method were introduced and the effects of various parameters on the determination of displacement outputs from the raw original and deformed image information were examined. Use of the normalized correlation coefficient, the use of 20 to 40 pixels for a searching window side, 6 variables searching, bi-cubic spline sub pixel interpolations and the use of coarse-fine search are some of the key choices among the results of parametric studies. The displacement outputs can be further processed with two dimensional curve fitting for the data noise reduction as well as displacement gradient calculation.

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Methods and Systems for High-temperature Strain Measurement of the Main Steam Pipe of a Boiler of a Power Plant While in Service

  • Guang, Chen;Qibo, Feng;Keqin, Ding
    • Journal of the Optical Society of Korea
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    • v.20 no.6
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    • pp.770-777
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    • 2016
  • It has been a challenge for researchers to accurately measure high temperature creep strain online without damaging the mechanical properties of the pipe surface. To this end, a noncontact method for measuring high temperature strain of a main steam pipe based on digital image correlation was proposed, and a system for monitoring of high temperature strain was designed and developed. Wavelet thresholding was used for denoising measurement data. The sub-pixel displacement search algorithm with curved surface fitting was improved to increase measurement accuracy. A field test was carried out to investigate the designed monitoring system of high temperature strain. The measuring error was less than $0.4ppm/^{\circ}C$, which meets actual measurement requirements for engineering. Our findings provide a new way to monitor creep damage of the main steam pipe of a boiler of an ultra-supercritical power plant in service.