检索结果-南通市图书馆

Geometric attack resistant image watermarking based on MSER

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Computer Science 2013年第1期7卷 145-156页

作者： Xuejuan ZHANG xiaochun cao Jingjie LI School of Computer Science and Technology Tianjin University Tianjin 300072 China State Key Laboratory of Information Security Institute of Information Engineering Chinese Academy of Sciences Beijing 100093 China

Geometric distortions are simple and effective at- tacks rendering many watermarking methods useless. They make detection and extraction of the embedded watermark difficult or even impossible by destroying the synchroniza- tion between the watermark reader and the embedded water- mark. In this paper, we propose a blind content-based image watermarking scheme against geometric distortions. Firstly, the MSER detector is adopted to extract a set of maximally stable extremal regions which are affine covariant and robust to geometric distortions and common signal processing. Sec- ondly, every original MSER is fitted into an elliptical region that was proved to be affine invariant. In order to achieve rota- tion invariance, an image normalization process is performed to transform the elliptical regions into circular ones. Finally, watermarks are repeatedly embedded into every circular disk by modifying the wavelet transform coefficients. Experimen- tal results on standard benchmark demonstrate that the pro- posed scheme is robust to geometric distortions as well as common signal processing.

关键词： image watermarking maximally stable ex- tremal region geometric distortions image normalization wavelet transform

Survey of recent progress in semantic image segmentation with CNNs

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2018年第5期61卷 107-124页

作者： Qichuan GENG Zhong ZHOU xiaochun cao State Key Laboratory of Virtual Reality Technology and Systems School of Computer Science and Engineering Beihang University State Key Laboratory of Information Security Institute of Information EngineeringChinese Academy of Sciences

In recent years, convolutional neural networks(CNNs) are leading the way in many computer vision tasks, such as image classification, object detection, and face recognition. In order to produce more refined semantic image segmentation, we survey the powerful CNNs and novel elaborate layers, structures and strategies, especially including those that have achieved the state-of-the-art results on the Pascal VOC 2012 semantic segmentation challenge. Moreover, we discuss their different working stages and various mechanisms to utilize the structural and contextual information in the image and feature spaces. Finally, combining some popular underlying referential methods in homologous problems, we propose several possible directions and approaches to incorporate existing effective methods as components to enhance CNNs for the segmentation of specific semantic objects.

关键词： semantic image segmentation CNN Pascal VOC 2012 challenge multi-granularity features construction of contextual relationships

Image composite authentication using a single shadow observation

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2015年第9期58卷 122-134页

作者： cao xiaochun ZHAO HanDong WANG Chuan ZHANG Wei State Key Laboratory of Information Security Institute of Information Engineering Chinese Academy of Sciences

The paper presents a novel method for image composite authentication based on a single shadow in an outdoor image. Existing methods based on the shadow geometry consistency involve more than two shadow observations. We relax the requirement of two shadow observations in the same scene. As a trade-off,we use the information in EXIF(Exchangeable Image File) based on which the ground truth sun elevation is calculated. We also estimate the sun elevation based on geometric constraints the scene provides, whose consistency serves as the cue to authenticate image forgery. It is the first attempt, to our best knowledge, to make use of sun elevation with shadow of one object to authenticate outdoor images. Also, the novel use of GPS(Global Positioning System), and Date and Time data of captured image makes image forensics possible even in one image containing a single shadow. Experimental results on both the synthetic data and visually plausible images demonstrate the performance of the proposed method.

关键词： image forensics solar shadow sun elevation exchangeable image file geometry-based technique

Research on axial bearing capacity of rectangular concrete-filled steel tubular columns based on artificial neural networks

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Computer Science 2017年第5期11卷 863-873页

作者： Yansheng DU Zhihua CHEN Changqing ZHANG xiaochun cao School of Civil Engineering Tianjin University Tianjin 300072 China School of Computer Science and Technology Tianjin University Tianjin 300354 China SKL of Information Security Institute of Information Engineering Chinese Academy of Sciences Beijing 100093 China

Design of rectangular concrete-filled steel tubular （CFT） columns has been a big concern owing to their complex constraint mechanism. Generally, most existing methods are based on simplified mechanical model with limited experimental data, which is not reliable under many conditions, e.g., columns using high strength materials. Artificial neural network （ANN） models have shown the effectiveness to solve complex problems in many areas of civil engineering in recent years. In this paper, ANN models were employed to predict the axial bearing capacity of rectangular CFT columns based on the experimental data. 305 experimental data from articles were collected, and 275 experimental samples were chosen to train the ANN models while 30 experimental samples were used for testing. Based on the comparison among different models, artificial neural network modell （ANN1） and artificial neural network model2 （ANN2） with a 20- neuron hidden layer were chosen as the fit prediction models. ANN1 has five inputs： the length （D） and width （B） of cross section, the thickness of steel （t）, the yield strength of steel （fy）, the cylinder strength of concrete （fc＇）- ANN2 has ten inputs： D, B, t, fy, f′, the length to width ratio （D/B）, the length to thickness ratio （D/t）, the width to thickness ratio （B/t）, restraint coefficient （ξ）, the steel ratio （α）. The axial beating capacity is the output data for both *** outputs from ANN1 and ANN2 were verified and compared with those from EC4, ACI, GJB4142 and AISC360-10. The results show that the implemented models have good prediction and generalization capacity. Parametric study was conducted using ANN1 and ANN2 which indicates that effect law of basic parameters of columns on the axial bearing capacity of rectangular CFT columns differs from design *** results also provide convincing design reference to rectangular CFT columns.

关键词： rectangular CFT columns artificial neural net-work axial bearing capacity model prediction parametricstudy

A new encryption scheme for surveillance videos

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Computer Science 2015年第5期9卷 765-777页

作者： xiaochun cao Meili MA Xiaojie GUO Ling DU Dongdai LIN School of Computer Science and Technology Tianjin University Tianjin 300072 China SKL Of Information Security Institute of Information Engineering Chinese Academy of Sciences Beijing 100093 China

In this paper, we propose a novel framework to encrypt surveillance videos. Although a few encryption schemes have been proposed in the literature, they are not sufficiently efficient due to the lack of full consideration of the characteristics of surveillance videos, i.e., intensive global redundancy. By taking advantage of such redundancy, we design a novel method for encrypting such videos. We first train a background dictionary based on several frame observations. Then every single frame is parsed into the background and foreground components. Separation is the key to improve the efficiency of the proposed technique, since encryption is only carried out in the foreground, while the background is skillfully recorded by corresponding background recovery coefficients. Experimental results demonstrate that, compared to the state of the art, the proposed method is robust to known cryptanalytic attacks, and enhances the overall security due to the foreground and background separation. Additionally, our encryption method is faster than competing methods, which do not conduct foreground extraction.

关键词： surveillance videos video encryption background and foreground separation

维普期刊数据库

Video color conceptualization using optimization

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2014年第7期57卷 173-183页

作者： cao xiaochun ZHANG YuJie GUO XiaoJie CHEUNG Yiu-Ming School of Computer Science and Technology Tianjin University Department of Computer Science Hong Kong Baptist UniversityHong Kong SARHong Kong 999077China

Color conceptualization aims to propagate"color concepts"from a library of natural color images to the input image by changing the main ***,the existing method may lead to spatial discontinuities in images because of the absence of a spatial consistency *** this paper,to solve this problem,we present a novel method to force neighboring pixels with similar intensities to have similar *** this constraint,the color conceptualization is formalized as an optimization problem with a quadratic cost ***,we further expand two-dimensional(still image)color conceptualization to three-dimensional(video),and use the information of neighboring pixels in both space and time to improve the consistency between neighboring *** performance of our proposed method is demonstrated for a variety of images and video sequences.

关键词： color conceptualization color discontinuity optimization color correspondence video sequence

Semi-fragile watermarking for image authentication based on compressive sensing

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2016年第5期59卷 248-250页

作者： Ling DU xiaochun cao Wei ZHANG Xinpeng ZHANG Na LIU Jianguo WEI School of Computer Science and Technology Tianjin University School of Computer Shenyang Aerospace University State Key Laboratory of Information Security Institute of Information EngineeringChinese Academy of Sciences School of Communication and Information Engineering Shanghai University

Dear editor,With the aid of sophisticated photoediting software,multimedia content security is becoming increasingly prominent[1,2].The problems of verifying the integrity and recovering the alterations have been a major research topic for information security and multimedia[3–6].Semi-fragile watermarking techniques are more powerful in dealing with such cases,which are fragile to malicious modifications meanwhile robust to incidental

关键词： DCT Semi-fragile watermarking for image authentication based on compressive sensing

Photochemical Degradation of Triadimefon in Seawater

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Ocean University of China 2008年第2期7卷 171-176页

作者： SUN xiaochun YANG Guipeng cao Xiaoyan LIN Zhifeng Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education Ocean University of China Qingdao 266100 P. R. China

The photochemical degradation of triadimefon in seawater was investigated under different reaction conditions in this study. The results showed that triadimefon could be effectively degraded by the irradiation of a high-pressure mercury lamp and the photodegradation rates were influenced by aquatic media, heavy metal ions and photosensitizers. The photochemical degradation of triadimefon followed the first-order reaction kinetic behavior, with the rate constants ranging from 0.0027 to 0.0128 min-1 under the studied conditions. The photolysis of triadimefon was slower in natural seawater than in distilled water or synthetic seawater. All the heavy metal ions studied in this paper had inhibition effects on the photolysis of triadimefon. Acetone, as a common photosensitizer, could accelerate the photolysis of triadimefon. Three photoproducts were identified by GC-MS analysis. Our study confirmed that photochemical degradation is an effective pathway to remove triadimefon in seawater.

关键词： triadimefon photochemical degradation seawater photoproducts kinetics

维普期刊数据库

在线全文

学校读者我要写书评

暂无评论

协同消费的营销视角:内涵、缘起、意蕴

河海大学学报（哲学社会科学版） 2019年第3期21卷 46-52,106,107页

作者：曹小春江苏省社会科学院

从营销角度看,协同消费是消费者之间直接或通过媒介供给和获取闲置物品或冗余服务的过程。其核心特征是消费者能够向其他消费者“供给”,而不管是否经由互联网、是否基于使用权。近年来,协同消费得到迅猛发展,主要原因在于技术的进步,... 详细信息

从营销角度看,协同消费是消费者之间直接或通过媒介供给和获取闲置物品或冗余服务的过程。其核心特征是消费者能够向其他消费者“供给”,而不管是否经由互联网、是否基于使用权。近年来,协同消费得到迅猛发展,主要原因在于技术的进步,特别是互联网的强有力支撑,与此同时,政治、经济、社会方面一些因素的变化也发挥了重要作用。对于营销者来说,需要采用宏观视角,将营销系统作为分析单位;此外,要注重培育人与人之间的信任关系、重视物品使用权的价值、强调产品使用中的低费用、关注有关法律和政策的变化及发展趋势。

关键词：协同消费共享经济营销整体营销系统

维普期刊数据库