极限学习机在图像隐写分析中的应用

为了有效提高图像隐写分析的检测正确率和速度,特结合单隐层前馈神经网络(SLFN)的特点,提出了一种基于极限学习机(ELM)的隐写分析方法.该方法首先根据Fridrich提出的多域特征提取算法从图像DCT域和空域中提取特征;得到193维原始特征;然后使用"主成份分析"法将其约简至18维;最后采用极限学习机作为分类方法构造隐写分析算法.实验表明,与目前隐写分析算法中广泛使用的支持向量机(SVM)相比,极限学习机参数调节少,学习速度快,以较少的隐层节点数取得了与SVM相似的检测正确率,能够实现针对各类JPEG图像隐写算法的有效检测.     

An adaptive scheme for compressed video steganography using temporal and spatial features of the video signal

Steganography is the art and science of data hiding. This article proposes an adaptive steganographic algorithm that embeds secret data in a compressed video stream using temporal and spatial features of the video signal and human visual system characteristics. Qualified‐DCT coefficients of I‐VOP and motion vectors of P‐VOP and B‐VOP are used for spatial and temporal features of the video, respectively. Embedded‐data are extracted without using the original video and there is no need for full decompression. Experimental results demonstrate that the proposed algorithm has high imperceptibility and capacity. Furthermore, the bit rate remains approximately constant. © 2009 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 19, 306–315, 2009     

Performance improvement of LSB-based steganalysis using bit-plane decomposition of images

In this paper, we present an improved least significant bit (LSB)-based steganalysis scheme using the bit-plane decomposition of images. We derive a mathematical condition that can enhance the detection rate for hidden messages based on the correlation coefficient between two parts of a decomposed image. Based on this condition, images are classified and segregated into two groups: the full image including all of the bit-planes and a sub-image containing only the lower bit-planes. The feature vectors for steganalysis are extracted independently form each group. Three types of conventional feature vectors were extracted to verify our proposed method and experiments demonstrated that conventional steganalysis schemes exhibited improved performance using our proposed method. In conclusion, our scheme can be used as a general steganalyzer regardless of the specific steganalysis methods employed for LSB-based steganalysis.     

Digital enhancement of video images for NDT

Due to recent advances in micro-electronics, many digital image enhancement techniques can now be readily applied at standard video-rates using commercially available hardware. These techniques are being increasingly applied in the field of nondestructive testing, in particular to methods that generate TV-type video images, such as real-time radiography and pulse-video thermography. The latest techniques used by the National NDT Centre at Harwell are described and are illustrated by examples from three application areas.     

一种用于AVS视频编码的块运动估计算法

通过对现有的视频图像编码中的帧间预测技术所用的运动估计算法的分析,提出了一种适用于AVS视频编码标准的快速而有效的块运动估计算法,该算法采用5个检测点的大菱形和9个检测点的小田字形双模板结构,通过调用大菱形模板和小田字形模板进行块运动匹配搜索,随着搜索的进行,大菱形模板可以被循环调用,但约定小田字形模板仅被调用一次.通过与全搜索算法和菱形搜索算法比较,这种新的块运动估计算法在保证编码性能几乎不变的情况下,编码复杂性能够得到有效的降低.     

Specific features of motion of rheopectic fluids

Results of an experimental and theoretical investigation of rheopectic fluid flows in tubes are presented. Loss of stability and appearance of periodic and random self-oscillations are shown to be possible during motion of media with shear-strengthened structures.Notation G mass flow rate of the fluid - w mean flow velocity - pressure gradient - t time - fluid density - R, L radius and length of the tube - c velocity of sound - shear stress - ₀ limiting shear stress - s concentration of structural bonds - rate of shear strain - coefficient determining the dependence of ₀ ons - time of retardation in the process of breakdown of structural bonds - , coefficients of restoration and destruction of structural bonds. Variables with asterisks denote certain characteristic values of the quantities Ufa Petroleum Instiute, Russian. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 66, No. 6, pp. 715–720, June, 1994.     

Optical flow-based motion compensation algorithm for very low-bit-rate video coding

In this article, we propose an efficient compression algorithm for very low-bit-rate video applications. The algorithm is based on (a) an optical-flow motion estimation to achieve more accurate motion prediction fields; (b) discrete cosine transformation (DCT) coding of the motion vectors from the optical-flow estimation to reduce the motion overheads; and (c) an adaptive threshold technique to match optical flow motion prediction and minimize the residual errors. Unlike the classic block-matching based DCT video coding schemes in MPEG-1/2 and H.261/3, the proposed algorithm uses optical flow for motion compensation and the DCT is applied to the optical flow field instead of predictive errors. Thresholding techniques are used to treat different regions to complement optical flow technique and to efficiently code residual data. While maintaining a comparable peak signal-to-noise ratio (PSNR) and computational complexity with that of ITU-T H.263/TMN5, the reconstructed video frames of the proposed coder are free of annoying blocking artifacts, and hence visually much more pleasant. The computer simulation are conducted to show the feasibility and effectiveness of the algorithm. Results at 11 kbps are presented which can be used for videophone applications in the existing public switched telephone network (PSTN). © 1998 John Wiley & Sons, Inc. Int J Imaging Syst Technol, 9, 230–237, 1998     

基于运动一致性的视频对象分割方法研究

视频运动对象检测和分割是图像处理中最具挑战性的问题之一。针对目前大部分分割算法相当复杂而且计算量大的问题，提出了一种基于运动一致性的视频对象分割方法。该方法从MPEG压缩码流中提取运动矢量场来分割视频对象，首先对运动矢量场进行滤波和校正，然后进行全局运动补偿得到对象的绝对运动矢量场，最后采用K-means聚类算法对运动矢量场进行聚类分析从而分割出感兴趣的视频运动对象。MPEG标准测试序列的试验结果证明，该方法是有效的。     

Non-stationary stochastic vector processes: seismic ground motion applications

A spectral-representation-based simulation algorithm is used in this paper to generate sample functions of a non-stationary, multi-variate stochastic process with evolutionary power, according to its prescribed non-stationary cross-spectral density matrix. If the components of the vector process correspond to different locations in space, then the process is also non-homogeneous in space (in addition to being non-stationary in time). The ensemble cross-correlation matrix of the generated sample functions is identical to the corresponding target. For the important application of earthquake ground motion simulation, an iterative scheme is introduced to generate seismic ground motion time histories at several locations on the ground surface that are compatible with prescribed response spectra, correlated according to a given coherence function, include the wave propagation effect, and have a specified duration of strong ground motion. Three examples involving simulation of earthquake ground motion are presented in order to demonstrate the capabilities of the proposed methodologies. In the first two examples, acceleration time histories at three points on the ground surface are generated according to a prescribed cross-spectral density matrix, while in the third example, the acceleration time histories are generated to be compatible with prescribed response spectra.     

A hybrid video codec with block-based and mesh-based motion compensation modes

This article presents a complete video codec which supports both block-based and mesh-based motion compensation modes. While the mesh-based modes are suitable for spatially continuous representation of in-plane rotations, zooms, and other motions that can be represented by parametric mappings, the block-based modes (especially overlapped block matching) perform better around motion boundaries. Therefore, a hybrid codec with block-based and mesh-based modes, which nicely complement each other, yields the best results over a wide range of video at low bit rates. Experimental results with MPEG-4 test sequences are shown to demonstrate the performance of the proposed hybrid codec. © 1998 John Wiley & Sons, Inc. Int J Imaging Syst Technol, 9, 248–256, 1998     

Multimodal magnetic resonance imaging for Alzheimer's disease diagnosis using hybrid features extraction and ensemble support vector machines

Magnetic resonance imaging (MRI) is increasingly used in the diagnosis of Alzheimer's disease (AD) in order to identify abnormalities in the brain. Indeed, cortical atrophy, a powerful biomarker for AD, can be detected using structural MRI (sMRI), but it cannot detect impairment in the integrity of the white matter (WM) preceding cortical atrophy. The early detection of these changes is made possible by the novel MRI modality known as diffusion tensor imaging (DTI). In this study, we integrate DTI and sMRI as complementary imaging modalities for the early detection of AD in order to create an effective computer-assisted diagnosis tool. The fused Bag-of-Features (BoF) with Speeded-Up Robust Features (SURF) and modified AlexNet convolutional neural network (CNN) are utilized to extract local and deep features. This is applied to DTI scalar metrics (fractional anisotropy and diffusivity metric) and segmented gray matter images from T1-weighted MRI images. Then, the classification of local unimodal and deep multimodal features is first performed using support vector machine (SVM) classifiers. Then, the majority voting technique is adopted to predict the final decision from the ensemble SVMs. The study is directed toward the classification of AD versus mild cognitive impairment (MCI) versus cognitively normal (CN) subjects. Our proposed method achieved an accuracy of 98.42% and demonstrated the robustness of multimodality imaging fusion.     

计算机视频泄漏信息的行同步特征提取技术

根据计算机视频泄漏信息在截获过程中显示出的不同特征,分别给出了行同步频率的谱分析算法,倾斜图像纹理特征的直线倾斜角度测量算法和漂移图像相位特征的积分投影微分定位的测量算法。利用这些算法在截获的图像中提取出频率、角度和相位差等特征,根据这些特征量可以自动调整行同步信号的频率,使偏差为零,达到稳定显示的目的。     

Performance enhancement of respiratory tumor motion prediction using adaptive support vector regression: Comparison with adaptive neural network method

The breathing motion moves internal organs and targeted regions determined by radiation therapy planning. For the radiation therapy, accurate prediction for breathing motion is of great interest as the outer targeted region treatment could endanger sensitive tissue. In this study, the use of a prediction algorithm with adaptive support vector regression (aSVR) was proposed and compared with the adaptive neural network (ANN) algorithm considering the prediction accuracy and training and predicting time. Respiration data from 87 patients treated by radiation therapy, were acquired with an optical marker at 30 Hz. Five types of prediction filters with the ANN or aSVR filters, were implemented and their performance was compared according to the size of the sliding window (2.5 and 5.0 sec), and the prediction latencies (100, 200, 300, 400, and 500 msec). Training and testing of the prediction algorithms with aSVR and ANN were performed. The root mean square error (RMSE) was used as the accuracy metric. The aSVR with an RBF kernel outperformed other prediction filters, including not only various types of ANN filters but also the aSVR with a linear kernel. A sliding window of 2.5 sec significantly and independently enhanced the overall accuracy. Otherwise, the training and prediction testing times were significantly prolonged in case of aSVR with an RBF kernel. The aSVR filter with the RBF kernel is in all cases superior to other filters regarding its accuracy; it also shows clinically applicable results from the viewpoint of training and predicting time, which may be effective for predicting patient breathing motion and thus enhancing the efficacy of radiation therapy.     

Target-acquisition performance in undersampled infrared imagers: static imagery to motion video

In this research we show that the target-acquisition performance of an undersampled imager improves with sensor or target motion. We provide an experiment designed to evaluate the improvement in observer performance as a function of target motion rate in the video. We created the target motion by mounting a thermal imager on a precision two-axis gimbal and varying the sensor motion rate from 0.25 to 1 instantaneous field of view per frame. A midwave thermal imager was used to permit short integration times and remove the effects of motion blur. It is shown that the human visual system performs a superresolution reconstruction that mitigates some aliasing and provides a higher (than static imagery) effective resolution. This process appears to be relatively independent of motion velocity. The results suggest that the benefits of superresolution reconstruction techniques as applied to imaging systems with motion may be limited.     

6D vector orthogonal transformation and its application in multiview video coding

Abstract

Multiview video (MVV) is multiple video sequences that integrated different viewpoints data of the same three-dimensional (3D) scene. Each viewpoint data are taken from the ordinary video camera. Thus, the data are very large for the MVV. So compression is necessary in order to store and transmit effectively. Based on the theory of multi-dimensional vector matrix (MDVM), we propose a six-dimensional (6D) vector orthogonal transform nuclear matrix, and prove its orthogonality and energy concentration. We apply the theory to multiview video coding (MVC). This transformation is based on discrete cosine transform (DCT), which has the optimal performance for video data. We represent MVV data with a multi-dimensional (MD) mathematical model. The chosen MVV is earlier eight frames in YUV format from two viewpoints. We divide the Y, U and V components into cubes respectively, and combine the two views data into one cube, on which the transformation is conducted. Good results are obtained in terms of energy concentration. This paper provides a new method for handling MVV, and prepare for the next quantisation and coding.     

Some special features of thermoconvective motion in multilayer liquids

Thermocapillary convection is considered in multilayer systems of liquids at whose interfaces surface tension forces act. It is assumed that the liquids are immiscible and a linear temperature distribution is maintained at the lower solid boundary.Institute for Problems of Mechanics, Russian Academy of Sciences, Moscow. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 65, No. 2, pp. 144–151, August, 1993.     

基于单矢量水听器的水面目标运动分析

介绍了一种基于单个三维矢量水听器对水面目标进行跟踪定位和运动速度估计的简单方法。首先利用平均声能流法得到目标波达方向的极大似然估计;当矢量水听器深度已知,由目标波达方向的估计序列可得到目标空间位置和运动速度的估计序列。但随着信噪比的降低,目标定向性能随之下降,导致目标位置和速度的估计误差急剧增大。针对直线运动目标,提出利用线性最小二乘法进行目标轨迹拟合的改进算法。仿真结果表明,拟合算法大大提高了目标定位精度和运动速度估计精度,增强了基于单矢量水听器的水面目标运动分析的结果的可靠性。     

Robust motion control design for dual-axis motion platform using evolutionary algorithm

This paper presents a new approach to deal with the dual-axis control design problem for a mechatronic platform. The cross-coupling effect leading to contour errors is effectively resolved by incorporating a neural net-based decoupling compensator. Conditions for robust stability are derived to ensure the closed-loop system stability with the decoupling compensator. An evolutionary algorithm possessing the universal solution seeking capability is proposed for finding the optimal connecting weights of the neural compensator and PID control gains for the X and Y axis control loops. Numerical studies and a real-world experiment for a watch cambered surface polishing platform have verified performance and applicability of our proposed design.     

Three-dimensional motion measurements using feature tracking

Feature tracking was developed to efficiently compute motion measurements from volumetric ultrasound images. Prior studies have demonstrated the motion magnitude accuracy and computation speed of feature tracking. However, the previous feature tracking implementations were limited by performance of their calculations in rectilinear coordinates. Also, the previous feature tracking approaches did not fully explore the three dimensional (3- D) nature of volumetric image analysis or utilize the 3-D directional information from the tracking calculations. This study presents an improved feature tracking method which achieves further computation speed gains by performing all calculations in the native spherical coordinates of the 3-D ultrasound image. The novel method utilizes a statistical analysis of tracked directions of motion to achieve better rejection of false tracking matches. Results from in vitro tracking of a speckle target show that the new feature tracking method is significantly faster than correlation search and can accurately determine target motion magnitude and 3-D direction.