Qiaoling Yuan

A survey of the image copy detection

This paper presents a review of recent as well as classic image copy detection method. The reviewed methods are classified as digital watermarking and contended based copy detection. The contended based copy detection usually extracts robust features from image directly that is the main difference from the digital watermarking which features are embedded before distribute. Some new and key techniques are discussed that applied in watermarking and CBCD. Main contributions, advantages, and drawbacks of the methods are mentioned in the paper. Problematic issues of image copy detection and outlook for the future research are discussed too. The major goal of the paper is to provide a comprehensive reference source for the researchers involved in image copy detection, regardless of particular application areas.

Principle of image encrypting algorithm based on magic cube transformation

A new method for digital image scrambling transformation, namely Magic Cube Transformation, was proposed and its principle was introduced. Combined with the Logistic mapping in non-linear dynamics system, an image encrypting and decrypting algorithm based on Magic Cube Transformation was designed. A natural chaotic sequence was created with the key. The image matrix was transformed with this chaotic sequence, using the Magic Cube Transformation. Then an encrypted image was resulted. The decrypting operation was the reverse process of encryption. The experimental results indicate that the proposed algorithm can get satisfying effect. Finally, the characteristics of the algorithm were summarized and the aspects of the subsequent work were prospected.

Optimal design of a linear Delta robot for the prescribed cuboid dexterous workspace

This paper presents a new idea to determine a set of optimal design parameters of a linear delta robot (LDR) whose workspace is as close as possible of being equal to a prescribed cuboid dexterous workspace (PCDW). The optimal design procedure on the basis of three algorithms is introduced in this paper. The kinematic problem is analyzed in brief to determine the design parameters and their relation. Two algorithms are designed to determine the reachable, rectangular dexterous workspace, and the maximal inscribed rectangle of dexterous workspace in the O-xy plane. Another algorithm is used to solve the optimal problem. As applying example, the results of four cases PCDW to LDR are presented. And the design result is compared with a new concept of the distance between the best state of the LDR and the requirement of the operation task. The method and result of this paper are very useful for the design and comparison of the parallel robot.

A Methodology for Determining the Maximal Regular-shaped Dexterous Workspace of the PMs

A methodology for determining the maximal regular-shaped dexterous workspace (MRsDW) of parallel manipulators (PMs) is proposed. The MRsDW is the maximal subset of the dexterous workspace with prescribed dexterity, and has a regular shape such as a circle or rectangle for the planar and a cuboid or cylinder for the spatial situation. It is one of the objects of optimal design of the PMs while the workspace size and shape are considered. The concept of the utilizable ratio of dexterous workspace (URDW) is introduced, which is a new measure for the rationality of design parameters of a PM. The methodology based on the stratified workspace boundary search technique can determine both the dexterous workspace and their MRsDW. After the problem of determination of the MRsDW is defined formally, a numerical method is proposed to solve this problem by three algorithms. Finally, the validity and efficiency of the proposed method are verified through application of the 2-DOF planar PM and the linear delta robot.

Optimal design of a linear delta robot for the prescribed regular-shaped dexterous workspace

This paper follows a method to determine a set of optimal design parameters of a linear Delta robot (LDR) whose workspace is as close as possible of being equal to a prescribed regular-shaped dexterous workspace (PRsDW). The design process proposed in this paper considers the particularity of the LDR. The kinematic problem is analyzed in brief to determine the design parameters and their relation at first. Two kinds of PRsDWs are considered, one is cylindrical dexterous workspace and the other is cuboid dexterous workspace. The optimal design parameters corresponding to the two kinds of PRsDWs are obtained by means of generalized pattern search algorithm (GPSA) in the genetic algorithm and direct search toolbox of Matlab, and the results of each PRsDW are compared to see the reasonability to the different operation tasks. The method and result of this paper are very useful for the design and comparison of the parallel robots.

Multivariate Statistical Modeling for Medical Image Compression Using Wavelet Transforms

With the promotion and application of digital imaging technology in the medical domain, the amount of medical image has grown rapidly. Recently variety of medical image compression methods using wavelet transforms have been proposed by many researchers. In this paper, we derive the general estimation rule in the wavelet domain to obtain the compression coefficients from the medical image based on the multivariate statistical theory. Multivariate model makes it possible to exploit the dependency between the estimated wavelet coefficients and their neighbours or other coefficients in different subbands. According to the multivariate model, a powerful compression scheme by means of wavelet transforms is presented. The experiments are done on the medical images including computed tomography (CT) and magnetic resonance imaging. The results show that under common objective conditions, our compression algorithm can achieve high subjective quality compressed image. Among the existing image compression methods using the same type of wavelet (Daubechies 8) filter, our results produce the highest peaksignal-to-noise ratio

Material Removal Model and Contact Control of Robotic Gasbag Polishing Technique

Material removal model of robotic gasbag polishing is established on the basis of Preston equation and distributions of linear velocity and contact stress in the circular contact area between the flexible polishing tool and mould surface. Contact force determines the maximal contact stress and influences the material removal and surface quality. Linear velocity and contact stress fields together with the distribution of material removal are calculated and simulated respectively according to certain internal pressure, downward depth, inclining angle, rotating speed and structural characteristics of rubber gasbag. The material removal mechanism is analyzed for optimizing the polishing process and trajectory planning is proposed for more convenient operation. The theoretical analysis and experimental results indicate that the surface roughness Ra 5 nm can be obtained under the situations of effective cushioning action of flexible contact, reliable control accuracy of robotic gasbag polishing system, tiny wiped off process of mould surface, etc.

Study of monitoring the abrasion of metal cutting tools based on digital image technology

As monitoring the abrasion of tools becomes more and more important during metal cutting, many research efforts have been made in this aspect. This paper proposed a new method that detect and measure it directly by digital image technology and developed a detecting and measure system based on digital image. It is prone to automatically disposed and to integrate with machining and control information. A new filter method that average many same size images when acquiring images is proposed. At the same time, a new edge detection way by wavelet transform is also proposed. A new wavelet function is given when selection wavelet functions, which describe gray change of images more availably, as well as may avoid the jamming of noise. The rule of three is proposed to calibrate this system in this paper, and calibration precision arrives at application requirement. Functions of the software of this system include acquiring and processing images, edge detecting and segmenting images, and measure and analysis images. Images of tools are acquired by camera and CCD and video card. It can automatically differentiate and pick-up available information of the original image, such as area and perimeter and width and length and the location of the center of the abrasion region, by image processing and segmenting.

Digital Media Copy Detection: Research Actuality and Prospect

This paper reviews and summarizes the copy detection of the digital media detailedly, which can be classified as digital watermarking and contended based copy detection. Then, set forth the research actuality of the text, image and video. Based on expounding the develop direction of the technology of the copy detection, and combining with the own research fruits, brings forward general conceive of the copy detection technology based on the focused factor navigation.

Research on LIF Image Denoising Based on Wavelet-Domain Multiscale HMT Model

In the process of computing laser induced fluorescence (LIF) image, a lot of noises will be brought into the system. Hidden Markov models have proven to be useful tools for statistical signal and image processing. In this paper, wavelet-domain multiscale hidden Markov tree HMT model is employed to denoise LIF image in order to acquire the process intermediate values of chemical mechanical polishing (CMP). This method utilizes the relativity of wavelet coefficients well. Firstly, the statistical characteristics of wavelet coefficients and transform are summarized. Then the dependencies between the wavelet coefficients are modeled as dependencies between the hidden states with the mixture Gaussian model and HMT model. Because the degree of coefficients shrinkage is determined based not only on the size of the coefficients but also on its relationship with its neighbors across scale, HMT-based denoising typically outperforms the standard threshold techniques. Finally, the experiments show that the denoising results of LIF image using this method are typically better than other standard method. The method can not only get rid of the noise preferably, but also increase the power signal-to-noise ratio (PSNR)