Pixel expansion-free grey-scale image sharing method

Abstract

In recent years, many visual secret sharing technologies have been proposed to protect the security of secret images (black and white, grey scale or colour images). In 2005, Lukac and Plataniotis used the concept of the Naor–Shamir method to propose a visual secret sharing technology for sharing secret grey-scale images based on bit-plane decomposition. Although their method can avoid pixel-value cutting problem, it still suffers from the pixel expansion problem. In this paper, we propose a new secret grey-scale image sharing method to improve this situation. In the proposed sharing image creation phase, two sharing images (one is grey-scale and the other is binary) are created and later shared by two protectors. The original secret image can be easily reconstructed if both sharing images are obtained. However, one cannot obtain the original secret image from each of the sharing images. Experimental results also show that the proposed method can effectively solve the pixel expansion problem.     

Multilevel image authentication using shared secret threshold and phase retrieval

A new kind of multilevel authentication system based on the (t, n) threshold secret sharing scheme and the iterative phase retrieval algorithm in Fresnel domain is proposed, in which, the first phase distribution iteratively generated is divided into n parts and delivered to n different participants, during high-level authentication, any t (t?≤?n) or more of them can be collected to reconstruct the original meaningful certification image; While in the case of low-level authentication, any t???1 or fewer will gain no significant information of certification image, however, it can result in a remarkable peak output in the nonlinear correlation coefficient of the recovered image and the standard certification image, which can successfully provide an additional authentication layer for the high-level authentication. Theoretical analysis and numerical simulations both validate the feasibility of our proposed scheme.     

Toward a secure protection scheme for visual secret sharing

Visual cryptography, proposed by Naor and Shamir in 1995, is a scheme which decodes messages by using human visual sensitivity. Cheating has been proved to be possible in visual cryptography. We propose a cheating prevention scheme which precludes members of a group from collusive cheating by using additional images for verification. In each pair of shared images, we detect cheating by mutually verification. The result of verification is clear and directly perceived by the senses. It is a practical technique using authenticating images while the structure of the secret is complex.     

完备秘密共享方案的条件

秘密共享方案是当今密码学研究的热点之一,它在信息安全领域有重要的应用,而关于秘密共享方案的完备性,即无条件安全性的证明则是一件不容易的事情。本文研究了一类特殊的秘密共享方案,提出了它完备性的条件,这一条件验证起来比较简单,易于操作,因而,对秘密共享方案的研究及设计具有一定的意义。     

Reduced reference blockiness and blurriness meter for image quality assessment

Abstract

This research work demonstrates an image quality assessment meter (IQAM) in reduced reference (RR) mode for discrete cosine transform (DCT) based compressed images. The DCT based image compression technique is lossy. As a result, it introduces blockiness and blurriness artefacts in the coded image. To send the image in image transmission systems, the system bandwidth is limited, and image data need to be adapted accordingly. To determine the quality of image at the recipient end, fewer image parameters are sent rather than the complete reference image. The aim of this paper is to suggest a method for the receiver to evaluate the objective received image quality. The presented RR quality meter operates in the frequency domain for the estimation of artefacts in the compressed image. The quality meter takes the image, performs edge detection, transforms it into the frequency domain and estimates the harmonics. The estimated strength of harmonics in the compressed image is compared with the received RR parameter for blockiness and blurriness distortions. For improved quality judgment, the combined effect of both these artefacts is measured as well. Peak signal to noise ratio (PSNR) is another most familiar method of image quality assessment. The received image quality is also observed by measuring the PSNR. The objective values of the artefacts obtained by the designed RR IQAM algorithm are correlated with the subjective differential mean opinion scores (DMOS) blockiness and blurriness values of Laboratory for Image and Video Engineering (LIVE) image database2. The results obtained are well matched and give 93–94% correlation with the LIVE database values, whereas the correlation obtained by PSNR values with LIVE DMOS values is only around 70%. This proves the practical application of the designed IQAM in RR.     

基于翻转操作的(2,n)异或图像分存方案

通过翻转操作来构造图像分存方案的新方法.所构造的分存方案将秘密图像以一种无需任何密码学知识的安全方式进行编码,且无需额外地隐藏处理过程就能生成有意义的分存图像.该分存方案没有像素膨胀,且不需要设计码本.秘密黑色像素的重构是完美的,所有的秘密黑色像素都能够被精准地恢复.首先利用翻转操作构造一个有意义的(2,2)方案,继而扩展出一个有意义的(2,n)方案.理论证明和实验结果表明了提出的分存方案正确和有效.     

Developing a temporary workforce transaction mechanism from risk sharing perspectives

In a low-profit environment, numerous firms no longer use traditional hiring practices and are forced to use a temporary workforce; these practices result in a more flexible workforce. Although outsourcing provides several benefits, it has a high level of risk. Therefore, implementing an enterprise risk management programme is crucial for using temporary labour. This study investigated the condition under which the multiperiod contract of a temporary work agency prohibits labour shortages. This investigation was performed to improve the effectiveness of dispatch contract designs. This study incorporated the concepts of labour demand forecasting and risk sharing and proposes two types of quantity flexibility contracts, period quantity adjustment and total quantity adjustment, to develop an optimal manpower dispatch contract model. An optimal manpower dispatch contract model must coordinate the interests of a temporary work agency and user firms to increase profits for both firms and must be flexible enough to allow for numerous order adjustments. To achieve this objective, this study used sensitivity analysis and an experimental design methodology to analyse the benefits of period quantity adjustment and total quantity adjustment and, accordingly, determine the factors that influence the total expected profit.     

Retinal image quality assessment through a visual similarity index

Retinal image quality is commonly analyzed through parameters inherited from instrumental optics. These parameters are defined for ‘good optics’ so they are hard to translate into visual quality metrics. Instead of using point or artificial functions, we propose a quality index that takes into account properties of natural images. These images usually show strong local correlations that help to interpret the image. Our aim is to derive an objective index that quantifies the quality of vision by taking into account the local structure of the scene, instead of focusing on a particular aberration. As we show, this index highly correlates with visual acuity and allows inter-comparison of natural images around the retina. The usefulness of the index is proven through the analysis of real eyes before and after undergoing corneal surgery, which usually are hard to analyze with standard metrics.     

Threshold proxy re-signature: definition and new constructions

The previous threshold proxy re-signature schemes have been mainly constructed with bilinear maps, the implementations of which are much more time-consuming than exponentiation operations. To solve this problem, we propose efficient threshold proxy re-signature schemes which are constructed with El-Gamal signatures. The performance analysis shows that our schemes are more efficient than the existing threshold proxy re-signature schemes. Based on the discrete logarithm problem, our schemes are provable secure in the random oracle model.     

Ex post demand information sharing between differentiated suppliers and a common retailer

We consider ex post demand information sharing in a two-echelon supply chain in which two suppliers sell differentiated products through a common retailer. We model three scenarios of information sharing to characterise the conditions under which information sharing may benefit or hurt different players: (1) no supplier is informed; (2) only one supplier is informed; and (3) both suppliers are informed. We find that the retailer may voluntarily share the low demand information when the product differentiation and demand magnitude satisfy certain conditions. In contrast, the retailer has no incentive to share the high demand information, even though this information benefits the suppliers. To achieve information sharing, we propose a side payment mechanism, which allows benefitted players to subsidise hurtful players. Finally, we extend our model by considering a situation where the suppliers have limited capacity and may invest to ramp up production capacity to satisfy a high demand.     

Decentralised capacitated planning with minimal-information sharing in a 2-echelon supply chain

This paper aims at modelling decentralised planning at the tactical level, with minimal-information sharing coordination, in a 2-echelon supply chain with multiple actors at each echelon. Suppliers manage production and storage at the upstream echelon, while retailers manage transportation and storage at the downstream echelon. The main features of the planning process are (1) decentralisation and coordination using contracts and sharing of only order/supply proposals, and (2) iteration on a rolling horizon. Actor planning is modelled as a capacitated lot-sizing problem on a finite horizon, with the focus on quality of service. The objective is to minimise costs, with a high lost sales penalty if demand is not met. Two other decision problems are pointed out and modelled with Mixed Integer Programming: (1) lost sales allocation between the retailers when their demands cannot be satisfied; and (2) allocation of orders between the suppliers. A multi-agent system combines simulation of the planning process and optimisation of the local decision processes. Several strategies, including retailers’ beliefs about suppliers’ production capacity are proposed and experimentally tested, with two patterns of production capacities. The results compare the proposed allocation strategies and highlight the relevance of the proposed framework for the studied planning problem.     

上海试剂资源联盟建设及共享服务

上海化学试剂研究所、上海师范大学、中国上海测试中心等五家单位在上海研发公共服务平台的基本框架下,积极组建上海试剂资源联盟,整合试剂资源,提高和促进试剂资源的共享服务。经过一段时间的试运行,上海试剂资源联盟初具规模,作为上海研发公共服务平台资源条件保障系统的一部分,充实了平台的服务内容,拓展了服务功能,为研究开发、创新创业提供了技术支撑。     

面向视觉检测的深度学习图像分类网络及在零部件质量检测中应用

基于深度学习图像分类是视觉检测应用的基本任务。该文系统总结基于模型深度化图像分类网络、基于模型轻量化图像分类网络及其他优化网络主要思想、网络结构、实现技术、技术指标、应用场景,指出网络模型深度化、轻量化分别有助于提高图像分类准确性、实时性。最后,面向零部件质量检测需求,应根据其类型多少、结构复杂程度、特征异同等特点,结合实时性要求,选择合适的图像分类网络构建零部件质量智能检测系统。     

一种图像局部模糊检测方法及其在被动图像认证中的应用

针对目前图像模糊检测算法复杂度过高和不能有效地实现图像局部模糊检测的问题,进行了图像局部模糊检测方法的研究,给出了模糊的数学模型,并基于此模型,提出一种简单有效的图像局部模糊的检测算法.该算法按照像素级搜索机制,对图像中各像素所在位置的相邻四邻域进行二维短时傅立叶变换,计算其频域系数的对数相关性,由此描述该区域的模糊程度,把它同预设阈值相比较,实现图像中局部模糊区域的检测.实验仿真显示,将该方法应用于篡改图像被动认证,可以有效地检测经过局部模糊和边缘模糊的篡改图像.     

Demand information sharing and channel choice in a dual-channel supply chain with multiple retailers

In this paper, under a dual-channel supply chain consisting of a manufacturer and multiple retailers, we investigate vertical and horizontal information sharing in different channel structures and the manufacturer’s choice on whether or not to keep a direct channel. To this end, we first study the dual-channel structure where uncertain demand is a linear function of price with a generalised-distribution base demand and show that the retailers have incentives to share information horizontally but not vertically, while the manufacturer is better off with vertical information sharing but its expected profit is not affected by horizontal information sharing. We next examine the retail-channel structure and find the basic results remain unchanged. Finally, we provide closed-form internal and external conditions under which the manufacturer can benefit from owning a dual-channel structure. Our study extends the existing literature by combining information sharing and dual-channel choice, introducing channel difference, discussing the impact of channel structure on horizontal and vertical sharing as well as providing interesting managerial insights for channel choice.     

A hybrid model of component sharing and platform modularity for optimal product family design

Today's industry faces new challenges such as diverse customer demands, shorter product development cycles and cost pressure, which compel manufacturing firms to change their production paradigm from one-size-fits-all mass production toward mass customisation. Over the past decades, modular design has received great attention as a key enabler for mass customisation, and component sharing and platform modularity have been quite popular strategies for modular design. While modular design approaches and their strategies offer a number of advantages such as late product differentiation and changeability, there are unfortunately negative aspects, for example, sales loss due to reduced performance compared to integral design approaches, which have received little attention. Therefore, we propose a hybrid model of the two strategies in order to develop the most profitable product family. A detailed numerical analysis provides empirical support for the feasibility and effectiveness of the hybrid model.     

Scheduling cluster tools for concurrent processing of two wafer types with PM sharing

We examine cyclic scheduling of single-armed and dual-armed cluster tools that concurrently process two wafer types by sharing a process module (PM). Because a PM is shared by two different wafers, the backward and swap sequences, which are prevalently used for single-armed and dual-armed tools without such complexity, respectively, are not effective. We therefore propose new sequences, called alternating backward and alternating swap sequences, for steady cycles of single-armed and dual-armed tools, respectively. We then develop optimality conditions for which the proposed sequences achieve the minimum cycle times in a fundamental cycle, and show that the optimality conditions hold for most practical cases. We also develop a condition for which a shared PM becomes the bottleneck and hence the PM sharing increases the cycle time. For general cycles, we propose heuristic scheduling methods that combine both the alternating backward (or swap) sequence and the conventional backward (or swap) sequence. Finally, we experimentally verify the efficiency and effectiveness of the proposed algorithm for dual-armed cluster tools.     

Decentralised decision-making with information sharing vs. centralised decision-making in supply chains

In recent years, implementing coordination mechanisms in decentralised supply chains to reduce the well-known negative effects of decentralisation, such as the ‘bullwhip effect’, has become a considerable challenge. Furthermore, with the dramatic developments in information and communication technologies, real-time information sharing has become increasingly easier to implement. In this work, we study a mono-product divergent supply chain composed of a supplier, a warehouse, retailers and customers in the context of decentralised and centralised decisions. The main objective of this study is to compare a decentralised supply chain combined with different scenarios of simultaneous upstream and downstream information sharing vs. a centralised supply chain. A mathematical model is developed to compare the logistics costs in the two decision contexts. The experimental results clearly show that the simultaneous sharing of customer demand and supplier-warehouse lead time information in a decentralised supply chain yields nearly equivalent logistics costs as the centralised supply chain context. However, the main beneficiary of the sharing is the warehouse, which receives approximately two-thirds of the benefit. Thus, incentives and revenue sharing contracts should be implemented to motivate and balance the benefits between supply chain partners.     

Coordination and performance analysis for a three-echelon supply chain with a revenue sharing contract

This paper focuses on a three-echelon supply chain composed of a manufacturer, a distributor and a retailer for a single selling period. Based on a revenue sharing contract, the coordination of the decentralised supply chain with the simultaneous move game or the leader–follower game is analysed. It is determined that the revenue sharing contract can coordinate the decentralised supply chain with the simultaneous move game. Our analysis reveals that the revenue sharing contract cannot coordinate the decentralised three-echelon supply chain with the leader–follower game except for a special situation. However, this result provides an opportunity to develop methodology and results that measure the potential improvement in supply chain performance that can be gained from utilising the revenue sharing contract. This is an important aspect of this paper.     

Game theoretic analysis of horizontal carrier coordination with revenue sharing in E-commerce logistics

This paper proposes comparisons among two different competitive power structures with and without horizontal coordination. We conduct a game theoretic analysis on the situation where two logistics service providers compete in an e-commerce logistics market with respect to the order quantity and service level decision on a particular logistics service product. Under a consumer utility-based demand, we acquire the equilibrium order quantity decisions and optimal profits under the centralised setting and decentralised setting. An analytical model is established to examine the existence of the Nash equilibrium in the service game. We then prove that the logistics service demand depends on different competitive power structures with the establishment of Cournot game and Stackelberg game model. The analytical results and the equilibrium analysis of the e-commerce logistics system are investigated. After that, we compare the equilibrium results among the centralised system, Cournot game, and Stackelberg game. To empower the horizontal carrier coordination, we design a revenue sharing contract for the decentralised model. A numerical study illustrates the impact of parameters on the optimal decision variables. In this paper, we prove the effectiveness of horizontal carrier collaboration and explicate the reason for the lower marginal profit in logistics theoretically.