共查询到20条相似文献,搜索用时 31 毫秒
1.
Zhihang Wang Xiangyang Ji Wen Gao Qingming Huang Debin Zhao 《Multimedia Tools and Applications》2007,35(2):175-202
This paper proposes a transcoding scheme from AVS to H.264/AVC. As high-compression video coding standards, H.264/AVC jointly
developed by MPEG and ITU and AVS developed by the Audio Video Coding Standard Working Group of China will co-exist in the
future market. Therefore, it is worthy to transcode the AVS format to the H.264/AVC format or vice versa. After an insight
into the inter transcoding from AVS to H.264/AVC, a simple and effective method is proposed by reusing the mode and motion
vectors to achieve high-efficient and fast transcoding. The problem in reusing the skip mode is studied and an effective method
to eliminate the artifacts is proposed. Furthermore, a fast intra transcoding algorithm based on the distribution of the DCT
coefficients is proposed to speed up the transcoding process. Detailed experiment results demonstrate that the proposed algorithm
can effectively reduce the transcoding complexity.
相似文献
Debin ZhaoEmail: |
2.
Barak Fishbain Leonid P. Yaroslavsky Ianir A. Ideses 《Journal of Real-Time Image Processing》2007,2(1):11-22
The paper presents a real-time algorithm that compensates image distortions due to atmospheric turbulence in video sequences,
while keeping the real moving objects in the video unharmed. The algorithm involves (1) generation of a “reference” frame,
(2) estimation, for each incoming video frame, of a local image displacement map with respect to the reference frame, (3)
segmentation of the displacement map into two classes: stationary and moving objects; (4) turbulence compensation of stationary
objects. Experiments with both simulated and real-life sequences have shown that the restored videos, generated in real-time
using standard computer hardware, exhibit excellent stability for stationary objects while retaining real motion.
相似文献
Barak FishbainEmail: |
3.
Real-time 2D to 3D video conversion 总被引:1,自引:0,他引:1
Ianir Ideses Leonid P. Yaroslavsky Barak Fishbain 《Journal of Real-Time Image Processing》2007,2(1):3-9
We present a real-time implementation of 2D to 3D video conversion using compressed video. In our method, compressed 2D video
is analyzed by extracting motion vectors. Using the motion vector maps, depth maps are built for each frame and the frames
are segmented to provide object-wise depth ordering. These data are then used to synthesize stereo pairs. 3D video synthesized
in this fashion can be viewed using any stereoscopic display. In our implementation, anaglyph projection was selected as the
3D visualization method, because it is mostly suited to standard displays.
相似文献
Ianir IdesesEmail: |
4.
Efficient video encryption scheme based on advanced video coding 总被引:1,自引:0,他引:1
Shiguo Lian Jinsheng Sun Guangjie Liu Zhiquan Wang 《Multimedia Tools and Applications》2008,38(1):75-89
A video encryption scheme combining with advanced video coding (AVC) is presented and analyzed in this paper, which is different
from the ones used in MPEG1/2 video encryption. In the proposed scheme, the intra-prediction mode and motion vector difference
are encrypted with the length-kept encryption algorithm (LKE) in order to keep the format compliance, and the residue data
of the macroblocks are encrypted with the residue data encryption algorithm (RDE) in order to keep low cost. Additionally,
a key distribution scheme is proposed to keep the robustness to transmission errors, which assigns sub-keys to different frames
or slices independently. The encryption scheme’s security, time efficiency and error robustness are analyzed in detail. Experimental
results show that the encryption scheme keeps file format unchanged, is secure against replacement attacks, is efficient in
computing, and is robust to some transmission errors. These properties make it a suitable choice for real-time applications,
such as secure IPTV, secure videoconference or mobile/wireless multimedia, etc.
相似文献
Shiguo LianEmail: |
5.
Jun Xin Jianjun Li Anthony Vetro Shun-ichi Sekiguchi 《Multimedia Tools and Applications》2007,35(2):203-223
This paper describes novel transcoding techniques aimed for low-complexity MPEG-2 to H.264/AVC transcoding. An important application
for this type of conversion is efficient storage of broadcast video in consumer devices. The architecture for such a system
is presented, which includes novel motion mapping and mode decision algorithms. For the motion mapping, two algorithms are
presented. Both efficiently map incoming MPEG-2 motion vectors to outgoing H.264/AVC motion vectors regardless of the block
sizes that the motion vectors correspond to. In addition, the algorithm maps motion vectors to different reference pictures,
which is useful for picture type conversion and prediction from multiple reference pictures. We also propose an efficient
rate-distortion optimised macroblock coding mode decision algorithm, which first evaluates candidate modes based on a simple
cost function so that a reduced set of candidate modes is formed, then based on this reduced set, we evaluate the more complex
Lagrangian cost calculation to determine the coding mode. Extensive simulation results show that our proposed transcoder incorporating
the proposed algorithms achieves very good rate-distortion performance with low complexity. Compared with the cascaded decoder-encoder
solution, the coding efficiency is maintained while the complexity is significantly reduced.
相似文献
Shun-ichi SekiguchiEmail: |
6.
Jinsong Wang Nilesh Patel William Grosky Farshad Fotouhi 《Multimedia Tools and Applications》2008,39(3):329-351
In this paper, we address the problem of video frame rate up-conversion (FRC) in the compressed domain. FRC is often recognized
as video temporal interpolation. This problem is very challenging when targeted for video sequences with inconsistent camera
and object motion, such as sports videos. A novel compressed domain motion compensation scheme is presented and applied in
this paper, aiming at up-sampling frame rates in sports videos. MPEG-2 encoded motion vectors (MVs) are utilized as inputs
in the proposed algorithm. The decoded MVs undergo a cumulative spatiotemporal interpolation. An iterative rejection scheme
based on the dense motion vector field (MVF) and the generalized affine motion model is exploited to detect global camera
motion. Subsequently, the foreground object separation is performed by additionally examining the temporal consistency of
the output of iterative rejections. This consistency check process helps coalesce the resulting foreground blocks and weed
out the unqualified blocks. Finally, different compensation strategies for the camera and object motions are applied to interpolate
the new frames. Illustrative examples are provided to demonstrate the efficacy of the proposed approach. Experimental results
are compared with the popular block and non-block based frame interpolation approaches.
相似文献
Jinsong WangEmail: |
7.
Three dimensional human motions recorded by motion capture and hand gestures recorded by using data gloves generate variable-length
data streams. These data streams usually have dozens of attributes, and have different variations for similar motions. To
segment and recognize motion streams, a classification-based approach is proposed in this paper. Classification feature vectors
are extracted by utilizing singular value decompositions (SVD) of motion data. The extracted feature vectors capture the dominating
geometric structures of motion data as revealed by SVD. Multi-class support vector machine (SVM) classifiers with class probability
estimates are explored for classifying the feature vectors in order to segment and recognize motion streams. Experiments show
that the proposed approach can find patterns in motion data streams with high accuracy.
相似文献
B. PrabhakaranEmail: |
8.
Eleanor Toye Richard Sharp Anil Madhavapeddy David Scott Eben Upton Alan Blackwell 《Personal and Ubiquitous Computing》2007,11(2):97-106
We present a study of using camera-phones and visual-tags to access mobile services. Firstly, a user-experience study is described in which participants were both observed learning to interact with a prototype mobile service and interviewed
about their experiences. Secondly, a pointing-device task is presented in which quantitative data was gathered regarding the speed and accuracy with which participants aimed and clicked
on visual-tags using camera-phones. We found that participants’ attitudes to visual-tag-based applications were broadly positive,
although they had several important reservations about camera-phone technology more generally. Data from our pointing-device
task demonstrated that novice users were able to aim and click on visual-tags quickly (well under 3 s per pointing-device
trial on average) and accurately (almost all meeting our defined speed/accuracy tradeoff of 6% error-rate). Based on our findings,
design lessons for camera-phone and visual-tag applications are presented.
相似文献
Eleanor Toye (Corresponding author)Email: |
Richard SharpEmail: |
Anil MadhavapeddyEmail: |
David ScottEmail: |
Eben UptonEmail: |
Alan BlackwellEmail: |
9.
Chun-Su Park Jun-Hyung Kim Sung-Jea Ko 《Journal of Mathematical Imaging and Vision》2007,28(3):279-284
The objective measurement of blocking artifacts plays an important role in the design, optimization, and assessment of image
and video compression. In this paper, we propose a novel measurement algorithm for blocking artifacts. Computer simulation
results indicate that the proposed method accurately measures the blocking artifacts without using the original image. Moreover,
the proposed algorithm can be easily implemented in both pixel and DCT domains.
相似文献
Chun-Su ParkEmail: |
10.
An improved variable-size block-matching algorithm 总被引:1,自引:1,他引:0
In this paper, we proposed an improved “bottom–up” variable-size block matching method. Different from previous work, the
proposed method does not need any threshold during the matching, and we just keep all the motion vectors leading to the minimum
matching error. A Marco-block mode prediction method is put forward to speed up the motion estimation procedure without introducing
any loss to the prediction precision. The improved variable-size block matching algorithm can achieve exactly the same prediction
precision as full-search based fixed-size block matching algorithm. In order to reduce the effect of illumination change on
mode selection, we proposed an illumination removal method, which acts as a post-processing step to prevent the macro-blocks
from over-splitting. Experiments show its encouraging performance.
相似文献
Hanqing LuEmail: |
11.
F. Essannouni R. Oulad Haj Thami D. Aboutajdine A. Salam 《Journal of Real-Time Image Processing》2007,1(4):257-265
Fast Fourier transforms (FFTs) which are O(N logN) algorithms to compute a discrete Fourier transform (DFT) of size N have been called one of the ten most important algorithms of the twentieth century. However, even though many algorithms
have been developed to speed up the computation the sum of absolute difference (SAD) matching, they are exclusively designed
in the spatial domain. In this paper, we propose a fast frequency algorithm to speed up the process of (SAD) matching. We
use a new approach to approximate the SAD metric by cosine series which can be expressed in correlation terms. These latter
can be computed using FFT algorithms. Experimental results demonstrate the effectiveness of our method when using only the
first correlation terms for block and template matching in terms of accuracy and speed. The proposed algorithm is suitable
for software implementations and has a deterministic execution time unlike the existing fast algorithms for SAD matching.
相似文献
A. SalamEmail: |
12.
MPEG-4 to H.264 transcoding with frame rate reduction 总被引:1,自引:0,他引:1
In this paper, a temporal resolution reduction transcoding method that transforms an MPEG-4 video bitstream into an H.264
video bitstream is proposed. The block modes and motion vectors in the MPEG-4 bitstream are utilized in the H.264 encoder
for the block mode conversion and motion vector interpolation methods. Four types of motion vector interpolation methods are
proposed in order to avoid the use of brute-force motion estimation in H.264. According to the experimental results, the proposed
methods achieve a 3∼4 times improvement in the computational complexity compared to the cascade pixel-domain transcoding method,
while the PSNR (peak signal to noise ratio) is degraded by 0.2∼0.9 dB depending on the bitrates.
相似文献
Yung-Lyul LeeEmail: |
13.
Streaming of scalable h.264 videos over the Internet 总被引:1,自引:0,他引:1
Aylin Kantarcı 《Multimedia Tools and Applications》2008,36(3):303-324
To investigate the benefits of scalable codecs in the case of rate adaptation problem, a streaming system for scalable H.264
videos has been implemented. The system considers congestion level in the network and buffer status at the client during adaptation
process. The rate adaptation algorithm is content adaptive. It selects an appropriate substream from the video file by taking
into account the motion dynamics of video. The performance of the system has been tested under congestion-free and congestion
scenarios. The performance results indicate that the system reacts to congestion properly and can be used for Internet video
streaming where losses occur unpredictably.
相似文献
Aylin KantarcıEmail: |
14.
This paper proposes an appearance generative mixture model based on key frames for meanshift tracking. Meanshift tracking
algorithm tracks an object by maximizing the similarity between the histogram in tracking window and a static histogram acquired
at the beginning of tracking. The tracking therefore could fail if the appearance of the object varies substantially. In this
paper, we assume the key appearances of the object can be acquired before tracking and the manifold of the object appearance
can be approximated by piece-wise linear combination of these key appearances in histogram space. The generative process is
described by a Bayesian graphical model. An Online EM algorithm is proposed to estimate the model parameters from the observed
histogram in the tracking window and to update the appearance histogram. We applied this approach to track human head motion
and to infer the head pose simultaneously in videos. Experiments verify that our online histogram generative model constrained
by key appearance histograms alleviates the drifting problem often encountered in tracking with online updating, that the
enhanced meanshift algorithm is capable of tracking object of varying appearances more robustly and accurately, and that our
tracking algorithm can infer additional information such as the object poses.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
相似文献
Jilin Tu (Corresponding author)Email: |
Hai TaoEmail: |
Thomas HuangEmail: |
15.
This paper proposes a framework to aid video analysts in detecting suspicious activity within the tremendous amounts of video
data that exists in today’s world of omnipresent surveillance video. Ideas and techniques for closing the semantic gap between
low-level machine readable features of video data and high-level events seen by a human observer are discussed. An evaluation
of the event classification and detection technique is presented and a future experiment to refine this technique is proposed.
These experiments are used as a lead to a discussion on the most optimal machine learning algorithm to learn the event representation
scheme proposed in this paper.
相似文献
Bhavani ThuraisinghamEmail: |
16.
Although scalable video coding can achieve coding efficiencies comparable with single layer video coding, its computational
complexity is higher due to its additional inter-layer prediction process. This paper presents a fast adaptive termination
algorithm for mode selection to increase its computation speed while attempting to maintain its coding efficiency. The developed
algorithm consists of the following three main steps which are applied not only to the enhancement layer but also to the base
layer: a prediction step based on neighboring macroblocks, a first round check step, and a second round check step or refinement
if failure occurs during the first round check. Comparison results with the existing algorithms are provided. The results
obtained on various video sequences show that the introduced algorithm achieves about one-third reduction in the computation
speed while generating more or less the same video quality.
相似文献
Jianfeng RenEmail: |
17.
Jens Wawerla Shelley Marshall Greg Mori Kristina Rothley Payam Sabzmeydani 《Machine Vision and Applications》2009,20(5):303-317
In this paper we describe the development of the BearCam, a camera system which was deployed in Fall 2005 to monitor the behaviour
of grizzly bears at a remote location near the arctic circle. The system aided biologists in collecting the data for their
study on bears’ behavioural responses to ecotourists. We developed a camera system for operating in the challenging arctic
conditions. We describe a novel “motion shapelet” algorithm for automatically detecting bears in the video captured by this
camera system. This algorithm is an extension of the shapelet features (Sabzmeydani and Mori in CVPR 2007), which are mid-level
features capturing pieces of shape. Our extension of this technique incorporates motion information and proves effective at
automatically detecting the occurrence of bears. We present quantitative results demonstrating that our algorithm can reliably
detect bears in the vast amounts of video footage collected by our system.
相似文献
Payam SabzmeydaniEmail: |
18.
Adaptation and application of multi-objective evolutionary algorithms for rule reduction and parameter tuning of fuzzy rule-based systems 总被引:7,自引:7,他引:0
María José Gacto Rafael Alcalá Francisco Herrera 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2009,13(5):419-436
Recently, multi-objective evolutionary algorithms have been applied to improve the difficult tradeoff between interpretability
and accuracy of fuzzy rule-based systems. It is known that both requirements are usually contradictory, however, these kinds
of algorithms can obtain a set of solutions with different trade-offs. This contribution analyzes different application alternatives
in order to attain the desired accuracy/interpr-etability balance by maintaining the improved accuracy that a tuning of membership
functions could give but trying to obtain more compact models. In this way, we propose the use of multi-objective evolutionary
algorithms as a tool to get almost one improved solution with respect to a classic single objective approach (a solution that
could dominate the one obtained by such algorithm in terms of the system error and number of rules). To do that, this work
presents and analyzes the application of six different multi-objective evolutionary algorithms to obtain simpler and still
accurate linguistic fuzzy models by performing rule selection and a tuning of the membership functions. The results on two
different scenarios show that the use of expert knowledge in the algorithm design process significantly improves the search
ability of these algorithms and that they are able to improve both objectives together, obtaining more accurate and at the
same time simpler models with respect to the single objective based approach.
相似文献
María José Gacto (Corresponding author)Email: |
Rafael AlcaláEmail: |
Francisco HerreraEmail: |
19.
The paper presents an automatic video summarization technique based on graph theory methodology and the dominant sets clustering
algorithm. The large size of the video data set is handled by exploiting the connectivity information of prototype frames
that are extracted from a down-sampled version of the original video sequence. The connectivity information for the prototypes
which is obtained from the whole set of data improves video representation and reveals its structure. Automatic selection
of the optimal number of clusters and hereafter keyframes is accomplished at a next step through the dominant set clustering
algorithm. The method is free of user-specified modeling parameters and is evaluated in terms of several metrics that quantify
its content representational ability. Comparison of the proposed summarization technique to the Open Video storyboard, the
Adaptive clustering algorithm and the Delaunay clustering approach, is provided.
相似文献
D. BesirisEmail: |
20.
OpenMP based parallel normalized direct methods for sparse finite element linear systems 总被引:1,自引:0,他引:1
George A. Gravvanis 《The Journal of supercomputing》2009,47(1):44-52
A new parallel normalized exact inverse algorithm is presented for solving sparse symmetric finite element linear systems
on symmetric multiprocessor systems (SMP), based upon an antidiagonal motion approach (“wave”-like pattern) for overcoming
the data dependencies. The proposed algorithm was implemented using OpenMP directives. Numerical results, such as speedups
and efficiency, are presented illustrating the efficient performance on a symmetric multiprocessor computer system, where
the proposed algorithmic solution method achieves good speedups.
相似文献
George A. GravvanisEmail: |