首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 125 毫秒
1.
This paper studies the evaluation methods for image compression algorithms and proposes test methods for compression algo- rithms including horizontal comparison test and vertical decomposition test. On the base of this, we design and realize a testing and analyzing tool for performance of image compression algorithms. This tool can test and analyze compression algorithms and generate kinds of analysis chart automatically, provides a lot of convenience for users and has very important practical value. In order to im- prove efficiency, veracity and perfectibility of the tool, this paper presents selection method for test images and analysis method for test results which have certain theoretical meaning.  相似文献   

2.
Engineering Drawing course is one of the main contents of teaching at most of science and engineering colleges or univer- sities. In this paper, some feasible measures is discussed on improving the teaching quality of Engineering Drawing course from four aspects, including diversified teacher participation and coordinating the teaching process, optimizing the content of teaching and im- proving teaching quality, improving teaching effect and reforming teaching methods, and integrating practice and cultivating practi- cal ability.  相似文献   

3.
A modified model predictive control scheme   总被引:1,自引:0,他引:1  
1 Introduction Model Predictive Control (MPC), also referred to as Receding Horizon Control (RHC), has been widely adopted in industry. It has many advantages over other control schemes, for example, it can easily deal with input constraints, can naturally handle multivariable systems, and can conveniently make most use of im- provements in other research fields[1~4]. The idea of MPC, simply put, is a form of control in which the current control action is obtained by solving on-line, at…  相似文献   

4.
Social network is a dominant , dis tinguishing characteristic of Silicon Valley. Because innovation entails coping with a high degree of uncertainty , such innovation is particularly de pendent on net- works. In Silicon Valley, networks have special im- portance in the movement of labor, the evolution of influence and power, and the actual production of innovation. One of the most important aspects of Silicon Valley is the way its labor market works. Extensive labor mobili ty creates rapidl…  相似文献   

5.
Software visualization and visual editing are important and practical techniques to improve the development of complex software systems. A challenge when applying the two technologies is how to realize the correspondence, a bidirectional relationship, between the data and its visual representation correctly. Although many tools and frameworks have been developed to support the construction of visual tools, it is still compli- cated and error-prone to realize the bidirectional relationship. In this paper, we propose a model-driven and bidirectional-transformation-based framework for data visualization and visual editing. Our approach mainly focuses on 1) how to define and manage graphical symbols in the model form and 2) how to specify and im- plement the bidirectional relationship based on the technique of bidirectional model transformation. Then, a prototype tool and four case studies are presented to evaluate the feasibility of our work.  相似文献   

6.
In the 1970s, Vapnik[1―3] proposed the Statistical Learning Theory (SLT), which deals mainly with the statistical learning principles when samples are limited. SLT is an im- portant development and supplement of traditional statistics, whose kernel idea …  相似文献   

7.
Enterprise architecture is a subject that has increased its importance in the small and medium enterprises in the manufacturing sector of the industry in Mexico. The global competitiveness of the markets has influenced the adoption of methodologies that support the strategic alignment of the processes with the goals and strategic objectives of the firms. The components of the business architecture like mission, vision, strategic objectives, products, organizational structure, business prdcesses, clients and geographic region, were collected from the firm of the case study for the design of the architecture. As a result of the practical application, an implementation model has been created and four strategic objectives were established for to improve productivity and competitiveness. This paper is a result of the architecture in a medium size manufacturing company like partial research project of analysis, design and implementing business architecture of an enterprise using ontologies for representing the core elements of the business architecture; the study presents clearly the importance of the strategic planning for the analysis and the detection of the main faults for the success of the achievement of goals and objectives.  相似文献   

8.
Facial expression and emotion recognition from thermal infrared images has attracted more and more attentions in recent years. However, the features adopted in current work are either temperature statistical parameters extracted from the facial regions of interest or several hand-crafted features that are commonly used in visible spectrum. Till now there are no image features specially designed for thermal infrared images. In this paper, we propose using the deep Boltzmann machine to learn thermal features for emotion recognition from thermal infrared facial images. First, the face is located and normalized from the thermal infrared im- ages. Then, a deep Boltzmann machine model composed of two layers is trained. The parameters of the deep Boltzmann machine model are further fine-tuned for emotion recognition after pre-tralning of feature learning. Comparative experimental results on the NVIE database demonstrate that our approach outperforms other approaches using temperature statistic features or hand-crafted features borrowed from visible domain. The learned features from the forehead, eye, and mouth are more effective for discriminating valence dimension of emotion than other facial areas. In addition, our study shows that adding unlabeled data from other database during training can also improve feature learning performance.  相似文献   

9.
复合型嵌入式软件人才培养模式探索与实践(英文)   总被引:1,自引:1,他引:0  
Today,the development of information technology is rapid,embedded software has been an increasing number of applications in various fields;the followed question of embedded software talents training bottlenecks has been paid more attention.The complex embedded software talents training mode is a new training model.Through exploration and practice,Software Technology Institute of Dalian Jiaotong University has accumulated a wealth of experience and achieved many results.This paper analyzes the problems of the traditional educational methods of the embedded major,discusses the way to build the complex embedded software talents training model and it's operational mechanism,and describes characteristics of the model.  相似文献   

10.
Because of its good condition with mechanics,logarithmic spiral double curve arch bam has been widely used in the practical engineering.The introduction of a new method in how to divide transverse joint in arch dam will be given and the further research of its calculation has been done.The C++ is used in electronic procedure and the 3D simulation has been finished with AutoCAD,which will provide the object model for computer simulation of the arch dam and the division of finite element mesh.Meanwhile,this method in dividing the transverse joint in arch dam also can be taken as the calculated basis for the design and calculation of arch dam,construction lofting and the calculation of the work amount.  相似文献   

11.
基于块参照像素的无损信息隐藏算法   总被引:1,自引:1,他引:0  
提出一种具有高嵌入容量的图像无损信息隐藏算法。首先将载体图像分成互不重叠的子块,然后在每块中选定一个参照像素,并计算参照像素与块内其它像素的差。在像素差直方图移位产生冗余空间之后,机密信息就可以无损地嵌入到这些冗余空间中。该方法在机密信息提取后可完全恢复载体图像,而且提取机密信息和恢复载体图像不需要除机密信息长度之外的任何信息。实验结果表明了该算法的有效性。  相似文献   

12.
The main challenges of image steganography are imperceptibility of the cover image and no recoverability of the secret data. To deal with these challenges, a modified digital image steganography technique based on Discrete Wavelet Transform (DWT) is proposed. In proposed approach, two new concepts are being proposed to minimize the distortion in the cover image. The first one i.e. secret key computation concept is proposed to make it more robust and resistive towards steganalysis. The second one, known as blocking concept, is introduced to ensure least variation in the cover image. The proposed approach is tested over ten different cover images and two secret images. Its performance is compared with the six well-known steganography techniques. The experimental results reveal that the proposed approach performs better than the existing techniques in terms of imperceptibility, security and quality measures. The six image processing attacks are also applied on the stego-image to test the robustness of the proposed approach. The effects of compression, rotation, and application of different wavelets have also been investigated on the proposed approach. The results demonstrate the robustness of the proposed approach under different image processing attacks. Both stego-image and extracted secret images possess better visual quality.  相似文献   

13.
基于图像平滑度的空域LSB嵌入的检测算法   总被引:1,自引:0,他引:1  
对图像像素值与邻域均值的差的分布进行建模,以该分布的方差定义了图像平滑度的概念,进而通过对消息嵌入、LSB平面取反带来的图像平滑度的变化进行分析,提出了针对空域LSB替换伪装算法的秘密消息长度估计算法,该算法可以准确地估计图像中嵌入的秘密信息数据量的大小.文中算法物理意义直观、实现简单、计算量小、计算速度快,有利于实现实时检测.实验结果表明该方法是有效的.  相似文献   

14.
Steganography is the science of hiding secret message in an appropriate digital multimedia in such a way that the existence of the embedded message should be invisible to anyone apart from the sender or the intended recipient. This paper presents an irreversible scheme for hiding a secret image in the cover image that is able to improve both the visual quality and the security of the stego-image while still providing a large embedding capacity. This is achieved by a hybrid steganography scheme incorporates Noise Visibility Function (NVF) and an optimal chaotic based encryption scheme. In the embedding process, first to reduce the image distortion and to increase the embedding capacity, the payload of each region of the cover image is determined dynamically according to NVF. NVF analyzes the local image properties to identify the complex areas where more secret bits should be embedded. This ensures to maintain a high visual quality of the stego-image as well as a large embedding capacity. Second, the security of the secret image is brought about by an optimal chaotic based encryption scheme to transform the secret image into an encrypted image. Third, the optimal chaotic based encryption scheme is achieved by using a hybrid optimization of Particle Swarm Optimization (PSO) and Genetic Algorithm (GA) which is allowing us to find an optimal secret key. The optimal secret key is able to encrypt the secret image so as the rate of changes after embedding process be decreased which results in increasing the quality of the stego-image. In the extracting process, the secret image can be extracted from the stego-image losslessly without referring to the original cover image. The experimental results confirm that the proposed scheme not only has the ability to achieve a good trade-off between the payload and the stego-image quality, but also can resist against the statistics and image processing attacks.  相似文献   

15.
In this paper we present the color local complexity estimation based steganographic (CLCES) method that is able of both preventing visual degradation and providing a large embedding capacity. A preprocessing stage is applied in the proposed scheme to improve the steganography security. The embedding capacity of each pixel is determined by the local complexity of the cover image, allowing good visual quality as well as embedding a large amount of secret messages. We classify the pixels using a threshold based on the standard deviation of the local complexity in the cover image to provide a compromise between the embedding capacity and the image visual quality. The experimental results demonstrated that the algorithm CLCES proposed produces insignificant visual distortion due to the hidden message. It provides a high embedding capacity that is superior respect to the offered by the existing schemes. The proposed method is a secure steganographic algorithm; it can resist the image quality measures (IQM) steganalysis attack. The RGB, YCbCr, and HSV color spaces are incorporated in the proposed scheme to ensure that the difference between the cover image and the stego-image which is indistinguishable by the human visual system (HVS). Finally, the proposed scheme is simple, efficient, and feasible for the adaptive steganographic applications.  相似文献   

16.
为了解决当前图像隐写方案存在阶梯效应,使其不可感知能力差,且其信息隐藏容量小(≤50%)等不足,本文设计了最优像素调整耦合基因算法的高容量图像隐写术。基于HDWT(Haara Discrete Wavelet Transform) 机制,构造隐藏信息长度计算模型,找出图像分块的频域表示,以改善隐写鲁棒性;根据载体图像与隐写图像之间的绝对误差,设计适应度函数,借助基因算法,获取最优映射函数,将秘密信息嵌入到HDWT系数中;并设计最优像素变换方案,降低载秘图像与载体图像之间的嵌入误差,显著增大隐写容量;再设计该算法的提取机制,获取信息图像;以PSNR(Peak Signal to Noise Ratio)构建反馈机制,优化提取质量。仿真结果显示:与其他隐写机制相比,本文算法具备更大的隐写容量和更强的不可感知性能;拥有更高的检测精度,可有效区分载体与隐写图像特征值。  相似文献   

17.
通过对原始图像和经过LSB隐写的隐蔽图像的分析,信息的再次嵌入对隐蔽图像与其位平面之间相关性的影响很小,而对原始图像与其位平面之间相关性的影响很大。以此为基础,提出了一种基于图像和其位平面之间的线性相关性的隐写分析方法,实现了对图像是否载密的检测。实验表明,对于图像的LSB隐写,可以进行有效的检测。该方法也可以对图像的其他位平面的嵌入进行分析。  相似文献   

18.
利用模运算及其周期性特点的安全隐写算法   总被引:1,自引:1,他引:0       下载免费PDF全文
为了提供较大的可调信息嵌入量和保持载密图像良好的视觉质量,提出一种基于模运算及其周期性特点的安全隐写算法。首先将秘密信息流转为n进制信息流表示,然后根据余数循环的特点,应用具有安全特性的模函数将一位n进制信息嵌入载体图像的一个像素中,直至信息嵌入完毕。选择不同的参数n可以得到不同的嵌入率和载密图像视觉质量。理论分析和实验结果表明,本文算法在保持高嵌入率的同时仍保持较好的载密图像视觉质量,且安全性好;其信息嵌入率选择具有高度弹性,可以根据实际要求选择在嵌入率和载密图像质量都很理想的隐写方案。与同类算法相比具有更强的实用性。  相似文献   

19.
In this paper, we present a new adaptive contourlet-based steganography method that hides secret data in a specific or automatically selected cover image. Our proposed steganography method primarily decomposes the cover image by contourlet transform. Then, every bit of secret data is embedded by increasing or decreasing the value of one coefficient in a block of a contourlet subband. Contourlet coefficients are manipulated relative to their magnitudes to hide the secret data adaptively. In addition to proposing contourlet-based steganography method, this work investigates the effect of cover selection on steganography embedding and steganalysis results. We demonstrate, through the experiments, that choosing suitable cover image by a proper selection measure could help the steganographer reduce detectability of stego images. The proposed technique is examined with some state-of-the-art steganalysis methods, and the results illustrate that an image can successfully hide secret data with average embedding capacity of 0.02 bits per pixel in a random selected cover image. Cover selection improves the embedding capacity up to 0.06 bits per pixel. Several experiments and comparative studies are performed to show the effectiveness of the proposed technique in enhancing the security of stego images, as well as to demonstrate its gain over the previous approaches in literature.  相似文献   

20.
Cheng-Hsing   《Pattern recognition》2008,41(8):2674-2683
Capacity and invisibility are two targets of the methods for information hiding. Because these two targets contradict each other, to hide large messages into the cover image and remain invisible is an interesting challenge. The simple least-significant-bit (LSB) substitution approach, which embeds secret messages into the LSB of pixels in cover images, usually embeds huge secret messages. After a large message is embedded, the quality of the stego-image will be significantly degraded. In this paper, a new LSB-based method, called the inverted pattern (IP) LSB substitution approach, is proposed to improve the quality of the stego-image. Each section of secret images is determined to be inverted or not inverted before it is embedded. The decisions are recorded by an IP for the purpose of extracting data and the pattern can be seen as a secret key or an extra data to be re-embedded. The experimental results show that our proposed method runs fast and has better results than that of previous works.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号