H.264 동영상 압축을 위한 부 화소 단위에서의 고속 움직임 추정 방법

이윤화(Yunhwa Lee),최명훈(Myunghoon Choi),신현철(Hyunchul Shin) 한국정보과학회 2006 정보과학회논문지 : 소프트웨어 및 응용 Vol.33 No.4

움직임 추정은 H.264의 비디오 코딩 과정에서 가장 많은 연산량을 차지하는 중요한 처리과정이다. 움직임 추정 과정에서 정수배 화소 단위에서의 탐색에 비하여, 1/2 화소 (half-pixel)와 1/4 화소 (quarter-pixel) 단위까지의 움직임 추정은 영상압축률을 높일 수 있지만, 계산의 복잡도가 늘어나는 문제가 있다. 본 논문에서는 각 블록간의 절대 오차 값인 SAD (Sum of Absolute Difference)가 최소 점을 기준으로 포물선 모양의 분포를 나타내는 특성 및 1/2 단위와 1/4 단위의 화소 보간 특성을 이용하여 움직임 추정 과정에서 탐색 점을 줄임으로써 처리속도를 증가시키고, 계산의 복잡도를 줄이는 알고리듬을 제안하였다. 제안한 방법에서는, 정수 화소 단위에서의 가장 작은 SAD를 갖는 점을 기준으로 주위 8점 가운데 두 번째로 SAD가 작은 점을 찾아 해당 방향으로 1/2 화소 단위의 움직임 추정을 행하였고, 1/4 화소 단위에서도 1/2 화소단위에서 두 번째로 SAD가 작은 점 방향으로 움직임 추정을 실행하였다. 그 결과 기존 알고리듬에 비해 비교적 화질에 변화가 없고, 인코더 처리과정 에서 약 20%의 빠른 속도로 처리하는 결과를 보였다. 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.

부화소 움직임 추정을 위한 고속 탐색 기법

박동균(Dong-Kyun Park),조성현(Seong-Hyeon Jo),조효문(Hyo-Moon Cho),이종화(Jong-Hwa Lee) 대한전기학회 2007 대한전기학회 학술대회 논문집 Vol.2007 No.4

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 units. 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.

Sub-Pixel Analysis of Hyperspectral Image Using Linear Spectral Mixing Model and Convex Geometry Concept

Kim, Dae-Sung,Kim, Yong-Il,Lim, Young-Jae Korean Society of Surveying 2004 Korean journal of geomatics Vol.4 No.1

In the middle-resolution remote sensing, the Ground Sampled Distance (GSD) that the detector senses and samples is generally larger than the actual size of the objects (or materials) of interest, and so several objects are embedded in a single pixel. In this case, as it is impossible to detect these objects by the conventional spatial-based image processing techniques, it has to be carried out at sub-pixel level through spectral properties. In this paper, we explain the sub-pixel analysis algorithm, also known as the Linear Spectral Mixing (LSM) model, which has been experimented using the Hyperion data. To find Endmembers used as the prior knowledge for LSM model, we applied the concept of the convex geometry on the two-dimensional scatter plot. The Atmospheric Correction and Minimum Noise Fraction techniques are presented for the pre-processing of Hyperion data. As LSM model is the simplest approach in sub-pixel analysis, the results of our experiment is not good. But we intend to say that the sub-pixel analysis shows much more information in comparison with the image classification.

Active Contour Method Based Sub-pixel Critical Dimension Measurement of Thin Film Transistor Liquid Crystal Display (TFT-LCD) Patterns

Jeong Hoon Lee,Tai-Wook Kim,Dong Hun Ku,Heui Jae Pahk 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.5

A novel application-oriented sub-pixel measurement method utilizing an active contour model with image resampling ispresented for a critical dimension (CD) measurement of pixel patterns of a fl at-panel thin fi lm transistor crystal display (TFTLCD)and organic light-emitting diode display. In modern manufacturing of fl at panel display, optical measurement of eachdimension of pixel patterns has a critical role in the process control, and the resolution of a measurement system becomesa limitation of the manufacturing process. Several methods have been developed to overcome this limit at the image postprocessing stage, but as the level of pixel integration and manufacturing throughput are increasing rapidly, more robust andeff ective inspection approach is required. In this paper, a novel sub-pixel level edge detection algorithm with active contourmethod and fast pixel resampling is proposed for micron scale CD measurement, and its advantages on measurement repeatabilityand noise handling are presented, along with the results of various industrial sample measurements and comparisonwith conventional critical dimension measurement algorithms.

적응적 2차원 FIR 필터를 이용한 부화소 렌더링 기법

남연오,최익현,송병철,Nam, Yeon Oh,Choi, Ik Hyun,Song, Byung Cheol 대한전자공학회 2013 전자공학회논문지 Vol.49 No.11

본 논문은 학습 기반의 2D-FIR필터를 이용한 부화소 렌더링 기법을 제안한다. 제안 기법은 크게 학습 단계와 합성 단계로 나뉜다. 학습 단계에서는 충분히 많은 수의 저해상도/고해상도의 영상 블록 쌍들을 이용하여 고해상도/저해상도 블록의 관계에 따른 합성 정보를 계산하고, 그 합성 정보를 담은 소위 사전을 생성한다. 합성 단계에서는 각 입력 영상에 대응하는 후보 블록을 상기 학습된 사전에서 찾는다. 탐색된 사전 내 합성 정보를 이용하여 부화소 레벨의 축소된 블록을 합성함으로써 최종 축소 영상을 얻는다. 한편, 영상 합성 시 디스플레이 장치의 RGB 패턴을 고려한 필터링을 통해 선명도를 향상시킨다. 모의 실험을 통해 제안 기법이 일반적인 영상축소 기법에 비해 흐림 효과, 엘리어싱 등의 화질 열화없이 고화질의 축소 영상을 생성함을 확인하였다. In this paper, we propose a sub-pixel rendering algorithm using learning-based 2D FIR filters. The proposed algorithm consists of two stages: the learning and synthesis stages. At the learning stage, we produce the low-resolution synthesis information derived from a sufficient number of high/low resolution block pairs, and store the synthesis information into a so-called dictionary. At the synthesis stage, the best candidate block corresponding to each input high-resolution block is found in the dictionary. Next, we can finally obtain the low-resolution image by synthesizing the low-resolution block using the selected 2D FIR filter on a sub-pixel basis. On the other hand, we additionally enhance the sharpness of the output image by using pre-emphasis considering RGB stripe pattern of display. The simulation results show that the proposed algorithm can provide significantly sharper results than conventional down-sampling methods, without blur effects and aliasing.

4K-UHD 영상을 지원하는 실시간 통합 복호기용 부화소 보간 회로 설계

이수정,조경순,Lee, Sujung,Cho, Kyeongsoon 한국전기전자학회 2015 전기전자학회논문지 Vol.19 No.1

본 논문은 4K-UHD 영상 크기를 지원하는 실시간 통합 복호기용 부화소 보간 회로를 제안한다. 제안하는 통합부화소 보간 회로는 H.264, MPEG-4, VC-1과 새로운 동영상 압축 표준인 HEVC를 지원한다. 회로의 면적을 줄이기 위해 각 표준에 해당하는 보간 알고리즘의 공통되는 부분을 공유하였다. 또한 회로의 저면적과 성능의 최적화를 위해 중간 버퍼를 효율적으로 사용하였다. 제안하는 통합 부화소 보간 회로를 130nm 표준 셀 라이브러리를 이용하여 합성한 결과, 회로의 크기는 122,564 게이트이고, 최대 동작 주파수 200MHz에서 4K-UHD 영상을 초당 35~86 프레임 속도로 처리한다. 따라서 제안하는 회로는 4K-UHD 영상을 실시간으로 처리할 수 있다. This paper proposes the design of sub-pixel interpolation circuit for real-time multi-decoder supporting 4K-UHD video images. The proposed sub-pixel interpolation circuit supports H.264, MPEG-4, VC-1 and new video compression standard HEVC. The common part of the interpolation algorithm used in each video compression standard is shared to reduce the circuit size. An intermediate buffer is effectively used to reduce the circuit size and optimize the performance. The proposed sub-pixel interpolation circuit was synthesised by using 130nm standard cell library. The synthesized gate-level circuit consists of 122,564 gates and processes 35~86 image frames per second for 4K-UHD video at the maximum operation frequency of 200MHz. Therefore, the proposed circuit can process 4K-UHD video in real time.

Compression of smart contents with classification between text and picture blocks using sub-pixel gradient information

Lee, Chulhee,Kim, Kyudong,Lee, Hyuk-Jae Elsevier 2018 Displays Vol.55 No.-

<P><B>Abstract</B></P> <P>This paper presents a novel algorithm to classify complex-rendered text images by examining the color levels of the adjacent sub-pixels. The proposed algorithm is different from the previous approaches in that it uses the combined characteristics of RGB sub-channels, whereas the previous approaches use independent characteristics of RGB sub-channels. Experimental results demonstrate that the proposed algorithm improves the classification accuracy over the previous best algorithm by 15.9% for complex-rendered texts. Furthermore, the compression method optimized for text sub-images significantly reduces the computational complexity without degradation in compression efficiency.</P> <P><B>Highlights</B></P> <P> <UL> <LI> This paper presents a novel algorithm to classify complex-rendered text images. </LI> <LI> The proposed algorithm uses the combined characteristics of RGB sub-channels. </LI> <LI> The classification accuracy is improved by 15.9% for complex-rendered texts. </LI> <LI> The computational complexity is reduced without compression efficiency degradation. </LI> </UL> </P>

Sub-Pixel Edge Detection Using Pseudo Zernike Moment

Amandeep Kaur,Chandan Singh 보안공학연구지원센터(IJSIP) 2011 International Journal of Signal Processing, Image Vol.4 No.2

Discrete Curvelet Transform Based Super-resolution using Sub-pixel Image Registration

Anil A. Patil,Dr. Jyoti Singhai 보안공학연구지원센터(IJSIP) 2011 International Journal of Signal Processing, Image Vol.4 No.2

스테레오 비전에서 향상된 적응형 퍼지 칼만 필터를 이용한 거리 추정 기법

임영철(Young-Chul Lim),이충희(Chung-Hee Lee),권순(Soon Kwon),이종훈(Jong-Hoon Lee) 대한전자공학회 2008 電子工學會論文誌-SC (System and control) Vol.45 No.6

본 논문에서는 스테레오 비전에서 시차를 이용하여 근거리뿐만 아니라 원거리의 장애 물체에 대해서도 신뢰성 있는 거리를 추정하기 위한 알고리즘을 제안한다. 시차를 이용한 거리 측정에서 양자화 오차는 원거리에서의 거리 정확도를 떨어뜨리게 되므로, 이를 최소화하기 위해 부화소 보간법(sub-pixel interpolation)을 이용하여 시차 정확도를 향상시키고, 거리 정확도 및 경로 추적의 최적화를 위해서 향상된 적응형 퍼지 칼만 필터(EAFSTKF : Enhanced Adaptive Fuzzy Strong Tracking Kalman Filter)를 사용한다. 제안한 방법은 차량과 같이 다양한 동적인 움직임에 의한 비선형성에 대하여 기존 칼만 필터에서 발생되는 발산 문제(divergence problem)를 해결할 수 있고, 거리의 정확도 및 신뢰도도 높일 수 있다. 몬테카를로(Monte Carlo) 방법을 이용한 모의실험 결과 제안한 방법은 기존 방법들과 거리 오차율(RMSER : Root Mean Square Error Rate)을 비교하였을 때, strong tracking Kalman filter(STKF)에 비하여 성능이 약 13.5%정도 향상되었음을 보여준다. In this paper, we propose an algorithm that can estimate the distance using disparity based on stereo vision system, even though the obstacle is located in long ranges as well as short ranges. We use sub-pixel interpolation to minimize quantization errors which deteriorate the distance accuracy when calculating the distance with integer disparity, and also we use enhanced adaptive fuzzy strong tracking Kalman filter(EAFSTKF) to improve the distance accuracy and track the path optimally. The proposed method can solve the divergence problem caused by nonlinear dynamics such as various vehicle movements in the conventional Kalman filter(CKF), and also enhance the distance accuracy and reliability. Our simulation results show that the performance of our method improves by about 13.5% compared to other methods in point of root mean square error rate(RMSER).