Inconsistency-tolerant reasoning with OWL DL The Web Ontology Language (OWL) is a family of description logic based ontology languages for the Semantic Web and gives well defined meaning to web accessible information and services. The study of inconsistency-tolerant reasoning with description logic knowledge bases is especially important for the Semantic Web since knowledge is not always perfect within it. An important challenge is strengthening the inference power of inconsistency-tolerant reasoning because it is normally impossible for paraconsistent logics to obey all important properties of inference together. This paper presents a nonclassical DL called quasi-classical description logic (QCDL) to tolerate inconsistency in OWL DL which is a most important sublanguage of OWL supporting those users who want the maximum expressiveness while retaining computational completeness (i.e., all conclusions are guaranteed to be computable) and decidability (i.e., all computations terminate in finite time). Instead of blocking those inference rules, we validate them conditionally and partially, under which more useful information can still be inferred when inconsistency occurs. This new non-classical DL possesses several important properties as well as its paraconsistency in DL, but it does not bring any extra complexity in worst case. Finally, a transformation-based algorithm is proposed to reduce reasoning problems in QCDL to those in DL so that existing OWL DL reasoners can be used to implement inconsistencytolerant reasoning. Based on this algorithm, a prototype OWL DL paraconsistent reasoner called PROSE is implemented. Preliminary experiments show that PROSE produces more intuitive results for inconsistent knowledge bases than other systems in general. As an extension of the World Wide Web (WWW), the Semantic Web [3] becomes more constantly changing and highly collaborative. Ontologies considered one of the pillars of the Semantic Web will rarely be perfect due to many reasons, such as modeling errors, migration from other formalisms, merging ontologies, and ontology evolution [35, 13, 32, 11, 28, 5] . As a fragment of predicate logic [8] , description logic (DL), which is the logical foundation of the Web Ontology Language [26] (e.g., sublanguages OWL Lite and OWL DL correspond to SHIF (D) and SHOIN (D) respectively), is unable to tolerate inconsistencies occurring in knowledge bases (KBs). Thus, the topic of inconsistency handling in OWL and DL has received extensive interests in the community in recent years [35, 32, 24] .. There are several approaches to handling inconsistencies in DLs. All of them can be functionally roughly classified into two different types. One type is based on the assumption that inconsistencies indicate erroneous data which are to be removed in order to obtain a consistent knowledge base (KB) [35, 13, 18, 33, 15, 22, 10] . In these approaches, researchers hold a common view that KBs should be completely free of inconsistencies, and thus try to eliminate inconsistencies from them to recovery consistency immediately by any means possible. However, there are some different opinions about the first type of treating inconsistency. For instance, [4] regarded the first type as "too simplistic for developing robust intelligent systems, and fails to use the benefits of inconsistent knowledge in intelligent activities, or to acknowledge the fact that living with inconsistencies seems to be unavoidable". And [4] argues that inconsistencies in knowledge are the norm in the real world, and so should be formalized and used, rather than always rejected. The other, called inconsistency-tolerant (or paraconsistent) approaches, is to not simply avoid inconsistencies but apply non-standard reasoning methods (e.g., non-standard inference or non-classical semantics) to obtain meaningful answers [38, 23, 30, 12, 45, 20, 29, 24, 43] . In the second type of approaches, inconsistency treated as a natural phenomenon in realistic data, should be tolerated in reasoning. So far, the main idea of existing paraconsistent methods for handling inconsistency is introducing either non-standard inference or non-classical semantics to draw meaning conclusions from inconsistent KBs [38] . Those paraconsistent approaches with non-standard inference presented by [43, 12] are employing argument principles where consistent subsets are selected from an inconsistent KB as substitutes in reasoning. Those paraconsistent approaches are based on multi-valued semantics (a popular kind of non-classical semantics) such as four-valued DL studied by [38, 23, 30, 24] based on Belnap's four-valued semantics [2] , paradoxical DL presented by [45] based on Priest's paradoxical semantics, three-valued DL discussed by [29] based on Kleene's three-valued semantics, and [20] based on a dual interpretation semantics.. Multi-valued logic, as a family of non-classical logics, are successful in handling inconsistency and uncertainty in DL such as four-valued DL [39, 23, 24] and fuzzy DLs [40, 6, 5, 9] . Because four-valued logic is a basic member of the family of multi-valued logics, four-valued semantics of DL has got a lot of attention [38, 23, 24] . However, the inference power of four-valued DL is rather weak as noted/argued by [23, 45, 20, 24] although three kinds of implications (namely, material implication, internal implication and strong implication, see Section 3) are introduced in four-valued DL to improve inference power. Some important properties (their formalizations can be found in Section 3.1) about inference such as disjunctive syllogism, resolution and intuitive equivalence are invalid in four-valued DL. For instance, assume that Wade is a student or a staff in a university and Wade is not a student. However, we do not conclude that Wade is a staff in that university since disjunctive syllogism fails in four-valued DL. And, though we know that all PhD students are students, we cannot infer that all persons are non-PhD students or students since intuitive equivalence also fails in four-valued DL. Moreover, there exist some quite differences among three implications. For instance, modus ponens is valid for internal implication and strong implication while it is invalid for material implication. Modus tollens is valid for strong implication while it is invalid for material implication and internal implication. Thus users have to make a suitable choice before reasoning. The weak inference power of four-valued DL is because a concept and its negation treated as two fully independent concepts.. We use two practical examples to show why the properties of disjunctive syllogism, modus ponens and modus tollens are useful in daily life ontology.. In wine ontology, 1 we have an axiom WineDescriptor ≡ WineColor WineTaste. If we additionally know that both WineDescriptor(Strong) and ¬WineColor(Strong), we will expect that Strong is a WineTaste, which can be inferred by the property of disjunctive syllogism.. In the Pizza ontology, we know that IceCream ¬Pizza. On the one hand, if we additionally know IceCream(a), we will expect ¬Pizza(a), which is captured by the property of modus ponens. In the other hand, if we additionally know Pizza(a), we will expect ¬IceCream(a), which is captured by the property of modus tollens. In addition, if we additionally know IceCream(a) and Pizza, then we will expect the inconsistency about a to be tolerated in the reasoning.. Indeed, the weak inference power is one of common characteristics of the family of paraconsistent logics where some important inference rules are prohibited in order to avoid the explosion of inference [4] . As a result, this topic of making more properties about inference valid under preventing the explosion of inference becomes interesting and important since more useful information can be inferred from inconsistent KBs [30] .. To avoid the shortcomings of four-valued DL, in this paper, we investigate the problem of defining a suitable non-classical DL based on the quasi-classical logic (QC logic) proposed by [19] . This problem is challenging in that it is not straightforward to extend the semantics of QC logic to DLs. Specifically, in the setting of DLs, it is difficult to define a suitable meaning for the two logical connectives " " and " ", which are two key constructors in DLs. To solve this problem, we define a new description logic called quasi-classical description logic (QCDL, for short), which allows to infer more useful information from inconsistent KBs. To achieve QCDL, we first extend the syntax of DLs by introducing a new connective called QC negation and then we introduce a new semantics for our proposal DL by two satisfactions, namely weak satisfaction and strong satisfaction. Informally, the former is to obtain a satisfactory paraconsistency while the latter is to make most properties of inference mentioned above (their formalization can be found in Section 2) valid. We show that QCDL can be applied to tolerate inconsistency in reasoning with DLs and our proposal approach can improve paraconsistent reasoning by using a different principle from four-valued DL. To employ off-the-shelf DL reasoners, we develop a transformation-based algorithm by reducing QCDL into classical DL and then implement a prototype reasoning system named prose. Our implementation can be seen as an extension of classical DL reasoners in this sense that prose can still infer meaningful information in an inconsistent ontology while classical DL reasoners will crash when there is an inconsistency. Finally, we show that the complexity of QC consistency problem in QCDL is not higher than that of consistency problem in DL. It should be noted that our technique can be feasibly extended in the whole DL family including SROIQ(D) (i.e., the logical foundation of OWL 2 [26] ). In this paper, we still use SHOIN (D), as a logical foundation of OWL DL, to simplify our discussion and make readers understand our technique clear.. Compared with classical QC logic [19] , a new connective defined in the syntax of QCDL called QC negation, is helpful for implementing paraconsistent reasoning in a intuitive way. Because of this, the language of DL is a sublanguage of QCDL. The semantics of QCDL can tolerate inconsistency occurring in DL KBs and two important reasoning tasks of QCDL can be reduced into the corresponding tasks of DL. Moreover, we define a suitable meaning for the two logical connectives " " and " ", which consist of two key constructors in DLs. In this sense, we generalize classical QC logic and discuss some new interesting reasoning tasks such as QC satisfiable problem and QC inconsistent problem in QCDL.. Our previous work [44] introduces primary quasi-classical semantics for ALC, a simple member of description logics, and presents some properties of it and the relationship with the method by using four-valued logic. However, we investigated that there exist three insufficiencies as follows:. 1. The approach presented in [44] is not enough to characterize all features of DLs. As we all known, DL is used in artificial intelligence (AI) for formal reasoning on the concepts of an application domain [1] . However, in our previous approach [44] , we did not really introduce a new logic with quasi-classical negation, but rather viewed negation as a transformation on formulas (axioms). This makes it impossible to directly represent the "opposite" concept of a given concept, because the negation of a concept ¬C is not taken as the "opposite" concept but rather as a concept unrelated to C . In this paper, we can directly introduce the QC negation of a concept as the "opposite" concept. Thus, we can further discuss QC satisfiable concepts. Moreover, our previous approach cannot capture the natural relationship between " " and " ".. 2. The basic approach of [44] cannot be generalized to more expressive description logics such as SROIQ(D) (i.e., the logical foundation of OWL 2 [26] ) which can be obtained by generalizing the present paper. One of important reasons is the complement of axioms ∼ φ presented in [44] cannot capture expressive DL axioms. For instance, ∼ ( n R.C )(a). cannot be represented by both (n − 1)R(a) and ∼ C (b). Instead, the QC negation of concept C introduced in this paper can capture expressive DL axioms, e.g.,. We investigated that the QC negation can also capture all DL axioms even in SROIQ(D). 3 . The complement of inclusions ∼ (C D) can be no longer translated into a corresponding DL concept inclusions. Because of this, it is impossible to transform this logic into classical DL. On the contrary, our proposal QCDL can be exactly transformed into DL.. In short, this paper does not merely attempt to give a QC semantics to a standard description logic, but instead we define a QC description logic (called QCDL).. This paper extends our previous DL-2009 and ESWC-2009 papers by developing a transformation-based algorithm and implementing it as a paraconsistent prototype reasoner. In addition, we analyze and evaluate some experimental results.. The rest of this paper is organized as follows: Section 2 reviews briefly DLs and paraconsistent logics. Section 3 introduces the syntax and semantics of QCDL and applies QCDL in paraconsistent reasoning with DL. Section 4 develops a transformation-based algorithm. Section 5 presents our prose and some evaluation results. Section 6 compares QCDL with others paraconsistent DLs. Finally, Section 7 concludes the paper. When the ontology is inconsistent, classical reasoners fail to answer any reasonable results, but both prose and ParOWL can still give some meaningful results under paraconsistent reasoning. As a successor of ParOWL, prose normally reports more results with classical truth value (T and F) and less results of unknown (U). The results of prose are in general more intuitive than those of ParOWL.. We also note that we did not show the running times of both systems in the table. The (strong and weak) transformations of prose and ParOWL are general very fast (linear time). However, it takes much more time for classical reasoners (e.g., Pellet) to answer over the transformed ontology, which is also confirmed in [24] . One possible reason is that the transformation introduce many negations and disjunctions, which makes the reasoning more difficult. Optimizing the performance is an interesting topic for future work. In this paper, we introduced a new description logic called quasi-classical description logic (QCDL) and investigated the properties and some important reasoning tasks of QCDL. We proved that QCDL can be used to tolerate inconsistency in reasoning with DL. We developed a transformation-based algorithm to transform QCDL to DL and reduce reasoning problems in QCDL to those in DL. Based on this algorithm, we have built a paraconsistent OWL DL prototype reasoner prose. The experiments showed that we have improved paraconsistent reasoning based on four-valued semantics. In this section, we mainly compare QCDL with existing paraconsistent DLs. Compared with four-valued DL [23, 24] , by Table 2 , we find that disjunctive syllogism (DS), intuitive equivalence (IE) and resolution hold in QCDLs while they do not hold in four-valued DLs. Moreover, modus ponens (MP) and modus tollens (MT) hold in QCDLs while they do not hold in four-valued DL with material inclusions and internal inclusions. Besides, the transitivity holds in four-valued DL while it does not hold in QCDLs. In this sense, the principle of tolerating inconsistency in reasoning with QCDL, where conclusions can be not allowed in next reasoning, is different from that of tolerating inconsistency in reasoning with four-valued DL, where a concept and the negation of that concept are no longer opposite to each other in all cases. In four-valued DL, there are three kinds of concept inclusions and a kind of role inclusions. Our work is integrating three kinds of inclusions (including concept inclusions and role inclusions) of four-valued DL into one kind of inclusions to make users more convenient and intuitive. More detailed comparison can be found in Table 2 .. Based on four-valued DL, two kinds of three-valued DLs, namely, paradoxical DL [45] and three-valued DL [29] are presented recently. Compared with four-valued DL, they mainly handle inconsistent knowledge but do not handle incomplete knowledge. A direct advantage of them is that they satisfy the excluded middle which fails in QCDL. However, because they are based on four-valued DL, they inherit most of features of four-valued DL including some shortages (in our view). For instance, the disjunctive syllogism, intuitive equivalence and resolution fail in both of them. Moreover, interpretations defined in paradoxical DL and three-valued DL are still four-valued interpretations with some restrictions while the weak interpretation in QCDL extends four-valued interpretation in QC negation of concepts. In addition, the strong interpretation in QCDL, which enhances inference power, is difficultly to represented in both paradoxical DL and three-valued DL.. There exist some variants of four-valued DL such as PALC presented in [20] . PALC is obtained from a description logic (called ALC n ∼ ) with such a dual (or multiple)-interpretation semantics by adding a weak negation in order to tolerate inconsistency where the weak negation is identical to the classical negation and the classical negation is identical to the QC negation in QCDL. The weak negation is used to tolerate inconsistency and the classical negation is used to implement paraconsistent reasoning. In PALC, the satisfaction of GCIs is defined by the internal inclusion. In this sense, PALC can be taken as our weak semantics for DL.. Recently, [17] presents a quasi-classical semantics for DL where each quasi-classical model is a subset of Herbrand base, which is obtained by grounding all concepts and roles in a Herbrand Universe (a set of constants). In this sense, we think that the semantics could be taken as some kind of restricted version of our proposal semantics. Besides, similar to the tableau in developed in [44] , the tableau calculus introduced in [17] works axioms while the tableau calculus is difficult to be technically extended in expressive DLs such as SHOIN (D).. Compared with paraconsistent approaches based on repairing [18, 33, 22, 10] where a new consistent KB or models of KB are restored from an inconsistent KB by removing some knowledge causing inconsistency, our approach does not reject any knowledge but tolerate inconsistent knowledge in reasoning.. Similarly, those paraconsistent approaches based on argumentation presented by [12, 43] introduce some partial orders (argument principles) of all consistent subsets of an inconsistent KB to select some expected consistent subsets for reasoning. Our approach adopts a totally different principle from those approaches. In addition, QCDL, including paradoxical DL, four-valued DL and PALC, is monotonic.. As an important member of the multi-valued DL family, fuzzy description logics [40, 6, 5, 9] can reason with uncertain knowledge in DL. Fuzzy DL admits truth values different from "true" and "false", each of which is intuitively taken as a certain degree. Usually, the set of possible truth values is the whole interval [0, 1]. Though some properties such as MP, MT and DS are valid in some fuzzy DL, the main difference between fuzzy logic and multi-valued logic is in the aims.

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Cooperative Wireless-Based Obstacle/Object Mapping and See-Through Capabilities in Robotic Networks Abstract-In this paper, we develop a theoretical and experimental framework for the mapping of obstacles (including occluded ones), in a robotic cooperative network, based on a small number of wireless channel measurements. This would allow the robots to map an area before entering it. We consider three approaches based on coordinated space, random space, and frequency sampling, and show how the robots can exploit the sparse representation of the map in space, wavelet or spatial variations, in order to build it with minimal sensing. We then show the underlying tradeoffs of all the possible sampling, sparsity and reconstruction techniques. Our simulation and experimental results show the feasibility and performance of the proposed framework. More specifically, using our experimental robotic platform, we show preliminary results in successfully mapping a number of real obstacles and having see-through capabilities with real structures, despite the practical challenges presented by multipath fading. M OBILE intelligent networks can play a key role in many different areas from emergency response, surveillance and security, and battlefield operations to smart homes and factories and environmental monitoring [2] , [3] , [4] . The vision of a multiagent robotic network cooperatively learning and adapting in harsh unknown environments to achieve a common goal is closer than ever.. An important issue key to the robust operation of a mobile robotic network is the accurate mapping of the obstacles. Yet the high volume of the information presented by the environment makes it prohibitive to sense all the areas, making accurate mapping challenging. In most related work, only areas that are directly sensed are mapped. The rich literature on Simultaneous Localization and Mapping (SLAM) and its several variations fall into this category [5] , [6] , [7] , [8] . SLAM approaches mainly focus on reducing the uncertainty in the sensed landmarks, by using a Kalman filter. Similarly, approaches based on generating an occupancy map also address sensing uncertainty [9] . Another set of approaches are based on the Next Best View (NBV) problem [10] , [11] , [12] , [13] , [14] . In NBV approaches, the aim is to move to the positions that are "good" for sensing, by guiding the vehicles to the perceived next safest area (area with the most visibility) based on the current map [10] . However, areas that are not sensed directly are not mapped in NBV.. In this paper, we are interested in cooperative obstacle/ object mapping and see-through capabilities, i.e., mapping of occluded obstacles. By obstacle/object mapping, we refer to building a spatial map of the obstacles or objects in the environment, where a nonzero value, at any position, indicates that there is an obstacle there, while a zero indicates otherwise. By cooperative obstacle/object mapping, we refer to a number of robots cooperating to generate a spatial map of the obstacles. Finally, by having seethrough capabilities, we refer to an approach that can map occluded obstacles. Consider the case where a number of robots want to build a map of the obstacles inside a building before entering it. Having see-through capabilities allows the nodes to assess the situation before entering the building and can be of particular interest in several applications such as emergency response, surveillance, security or battlefield operation [15] . It furthermore allows the robots to map the obstacles for navigation purposes, without having to sense them directly. In general, devising see-through mapping strategies can be considerably challenging and cannot be achieved with the traditional sensing and mapping techniques.. In this paper, we develop a framework for the cooperative mapping of obstacles (including occluded ones) in robotic networks, by only using a small number of wireless transmissions and utilizing the new theories of compressive sensing. Using wireless transmissions allows us to map the areas that are not directly sensed. However, it is very challenging to extract obstacle information from a wireless reception, without making a prohibitive number of measurements, due to several propagation phenomena. We then show how to properly develop the necessary theoretical and experimental framework to extract this information, based on a small number of wireless measurements, by 1) using the recent breakthroughs in nonuniform sampling theory [16] , [17] and 2) properly designing a robotic platform to limit multipath fading in practice.. A survey of the existing work in the literature shows few papers that use wireless measurements for the cooperative mapping of occluded obstacles in robotic networks. There are, however, a number of papers on detecting an object, using fixed sensors. For instance, in [15] , authors use a transmitter that is buried underground and several fixed receivers on the surface to detect underground tunnels/ facilities using radar. In [18] , [19] , the authors build a network of 28 fixed sensors in order to track a person, based on making several measurements between pairs of sensors. In [20] , [21] , we discussed the original idea that compressive sensing can be used for estimating a spatial field in three different applications: aerial mapping, mapping of a communication field to a fixed transmitter, and mapping of obstacles. In the area of obstacle mapping, the part relevant to this paper, that paper introduced the initial idea that wireless transmissions can be used for cooperative obstacle mapping in robotic networks, where we proposed mapping based on frequency sampling. In this paper, we extend our previous work to develop a comprehensive theoretical and experimental framework for wireless-based obstacle mapping based on different sampling, sparsity and reconstruction approaches.. Let an obstacle map refer to a 2D (or 3D) map of the environment, where we have zeros at locations where there are no obstacles and nonzero values at obstacle locations. Each nonzero value, for instance, could be the decay rate of the wireless signal within the object at that location, as we shall see in Section 3. In this work, we present a comprehensive foundation for obstacle mapping, based on a small number of wireless measurements and develop the necessary robotic experimental setup so that the map can be extracted, with minimal sensing, despite the practical challenges presented by multipath fading. More specifically, we propose three approaches based on coordinated space, random space, and frequency sampling. We show how the vehicles can utilize the sparse representation of the map in space, wavelet, or spatial variations, in order to reconstruct the map cooperatively, based on minimal measurements, and more importantly with a seethrough capability. We develop a comprehensive framework to shed light on the underlying tradeoffs of different sampling, sparsity, and reconstruction techniques. We furthermore show how to properly develop an experimental robotic setup, including antenna control, to implement the proposed approach. We then use our experimental setup and show the performance of our framework in efficiently mapping a number of real obstacles (including completely blocked ones), with their details, based on only very few wireless channel measurements. We emphasize that we do not view this framework as a replacement for the current obstacle sensing and mapping techniques. We rather view it as a complement to the existing approaches, by providing a see-through capability.. The paper is organized as follows: In Section 2, we provide an overview of compressive sampling theory and different relevant reconstruction techniques. In Section 3, we show how wireless measurements can be used for obstacle mapping. In Section 4, we propose different approaches for sampling, sparsity, and reconstruction of an obstacle map and show the underlying tradeoffs. Section 5 then discusses our experimental platform and shows the performance of our framework in mapping a number of real structures. We conclude in Section 6.

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A study of depth/texture bit-rate allocation in multi-view video plus depth compression A study of depth/texture bit-rate allocation in Multi-View Video plus Depth compressionReceived: date / Accepted: date Abstract Multi-view Video plus Depth (MVD) data offer a reliable representation of three dimensional (3D) scenes for 3D Video applications. This is a huge amount of data whose compression is an important challenge for researchers at the current time. Consisting of texture and depth video sequences, the question of the relationship between these two types of data regarding bitrate allocation often raises. This paper questions the required ratio between texture and depth when encoding MVD data. In particular, the paper investigates the elements impacting on the best bit-rate ratio between depth and color: total bit-rate budget, input data features, encoding strategy, assessed view. 3D video applications rely on exhaustive 3D representations of real or synthetic scenes. Among the numerous possible representations [1] are the Multi-View Video plus Depth (MVD) sequences. They consist of multiple texture video sequences coupled with depth video sequences, acquired at different viewpoints of the represented scene. The question of MVD compression is delicate because artifacts in 3D video sequences raise new and unsolved issues related to human vision mechanisms [2] .. Both 3D video applications, namely Free Viewpoint Video (FVV) and 3D Television (3DTV), require the synthesis of novel viewpoints in order to stimulate human vision system and to simulate parallax motion. This is achieved thanks to Depth Image Based Rendering (DIBR) [3] algorithms that use both texture and depth data. Since the quality of the synthesized views depends on the contribution of both texture and depth data, the issue of bit rate allocation between these two types of data must be addressed when designing an MVD coding framework.. Many approaches proposed a solution to the depth/texture bit-rate allocation issue but the optimal ratio criterion remains open. At the beginnings, the objective quality of the depth map was thought to be comparable to that of the color image. Then by the same token, the color signal having three components and the depth signal having only one component, it seemed appropriate to allocate 25% of the total bit-rate to depth data. Besides, in [3] , Fehn et al. show that being a gray-scale signal, the depth video can be compressed more efficiently than the texture video and recommend using less than 20% of the texture bit-rate for video-plus-depth data format. This recommendation is based on the fact that "the per-pixel depth information doesn't contain a lot of high frequency components" [3] . In this approach proposed by the AT-TEST project [3, 1] , a base layer encodes a conventional 2-D colour video using MPEG-2 and an advanced layer encodes the depth information. Yet, depth maps define the very structure of the scene. Artifacts occurring in critical areas of the depth map may lead to fatal synthesis errors when generating virtual views. Critical areas are known to be the sharp depth planes edges (i.e. high frequencies) whose encoding is costly and particularly prone to errors. To address this problem other studies [4] proposed to consider the distortion of the depth information. In [4] , Daribo et al. proposed a coding method for the video-plus-depth data through a joint estimation of the MV field for the texture motion information and the depth map sequence. This coding method also includes a bit-rate allocation strategy between the texture and depth map stream based on a rate-distortion criterion. Both the distortion (Mean Squared Error, MSE) of texture and depth data are taken into account in the proposed model of [4] . However, a previous study [5] also shown that the distortion of depth maps in terms of MSE may not be appropriate to predict the quality of the resulting synthesized views. In addition, since the depth map will not actually be observed by the users of an 3D Video application, it seems more pertinent to consider the quality of the synthesized views, that are more likely to be observed.. Thus, most of the up-to-date bit-rate allocation strategies now rely on the quality of the synthesized views. This is motivated by the realization of the impact of depth map compression on visual quality of the synthesized views ( [6] , [7] ). Different bit-rate allocation strategies have been proposed in the literature. Some of them opt for the fixed-ratio bit-allocation scheme, like Martinian et al. [8] who consider using only 5-10% of the total bit-rate for encoding depth data with H.264/AVC, based on the observation that it "produced acceptable view synthesis performance".. Other strategies [9, 10, 11] rely on a global optimization equation solver based on the objective image quality of the rendered intermediate view. In their experiments [9] , Ekmekcioglu et al. consider a given total budget where 15% is assigned to depth data. The authors noticed that their proposed bitallocation strategy based on the synthesized view quality, outperforms the conventional constant-ratio allocation strategy. Similarly, in [10] , the authors proposed an efficient joint texture/depth rate allocation method based on a view synthesis distortion model, for the compression of MVD data. According to the bandwidth constraints, the method delivers the best quantization parameters combination for depth/texture sets in order to maximize the quality of the rendered synthesized view in terms of MSE (Mean Squared Error) (with respect to the original captured view). The proposed model finds the optimal ratio between depth bit-rate and texture bit-rate. However, the optimization depends on the target virtual viewpoint. In [11] , the authors proposed a bit-rate allocation strategy between texture and depth maps of multi-view images based on a model that minimizes the distortion of the synthesized views. A cubic distortion model based on basic DIBR properties drives the optimal selection of coded views and quantization levels for corresponding texture and depth maps. Cheung et al. ( [11] ) observe improvements by up to 1.5 dB with this proposed model, compared to constant-ratio allocation strategy. The 3D-HTM coding software under standardization of MPEG includes a depth coding tool called View Synthesis Optimization (VSO) [12] that is meant to improve depth bit-rate allocation based on the quality of a synthesized view. This tool integrates a distortion term calculated based on the quality of texture synthesized using decoded depth. This previous work on bit-rate allocation between texture and depth data highlights the fact the challenges raised by this issue. These challenges are not that trivial since they seem to involve many questions:. -the importance of the preservation of depth sharp edges (discontinuities) -the influence of the target intermediate synthesized viewpoint used for the optimization process -other questions such as the bit-rate allocation within one frame, or between frames Based on our previous studies [13, 14] , we rely on the assumption that there exists an optimal ratio between texture and depth data. The experiments presented in this paper investigate the factors impacting on the optimal ratio between texture and depth data in MVD compression. In particular, we question the role of 1) the total bit-rate budget, 2) the coding method, 3) the input data features and 4) the location of the assessed view with respect to the decoded reference views. This paper aims at determining the impact of these four aspects in the bit-rate allocation between texture and depth data, in the con-text of MVD data compression in FVV applications by using objective metrics.. The study includes the compression of MVD data sequences at different bit-rates in order to determine the best bit-rate distribution between depth and texture, when based on Peak Signal to Noise Ratio (PSNR) measures of the synthesized view. In most of the studies, the use of this objective metric is justified by its simplicity and mathematical easiness to deal with such purposes. Thus, we also investigate the bit-rate allocation issue when based on such a metric.. The paper is organized as follows: Section 2 presents the experimental protocol basis. The next sections present the results of our investigations depending on the studied element assumed to impact on the bit-rate between texture and depth data: Section 3 addresses the analysis of the coding constraints; Section 4 addresses the influence of the MVD sequences features and of the assessed viewpoint. Finally Section 5 concludes the paper. This paper aimed at determining the elements impacting on the best ratio between texture and depth data in MVD compression. Different experiments following the same basis explored several assumed factors. The experiments consisted in encoding both texture and depth data with a given compression scheme, varying the ratio between texture and depth information and analyzing the quality of the rendered virtual view. A first study consisted in investigating the influence of the encoding method on the best ratio between texture and depth data. The test codecs were H.264/MVC coder in the first case of use, and HEVC in the second case of use. Depending on the encoding method, the attributed depth ratio allowing the best synthesizeed image quality in terms of PSNR was different. This suggests that bit-rate savings can be achieved if the encoding method is adapted to depth features, allowing better synthesized views quality. The experiment also showed that the ratio allocated to depth should decrease when the total bit-rate budget decreases. Another aspect investigated in this paper concerns the impact of the input data features. A relevant remark regards the observation that the optimal ratio is significantly different depending on the sequence. The factors related to the sequences have been studied. The assumed factors influencing the best trade-off for bit-rate allocation between texture and depth data were the depth map entropy, its complexity coupled with the camera baseline distance, and the contrast of neighboring background/foreground pixel areas. The experiments revealed the existence of their impact on the best trade-off for bit-rate allocation between texture and depth data.. Despite its limitations regarding the used quality assessment tools, this study raises new topics for future work: the influence of the synthesis method on the best ratio; the investigation of the reasons why the best quality of reconstruction by using VSRS requires different depth/texture ratios depending on the content; the consideration of depth maps features for the design of depth-adapted efficient compression methods for bit-rate savings. Such investigations could be useful for the implementation of an automatic bit-rate allocation method in coding methods. In addition, this work could be extend by considering the subjective quality of the synthesized views.

O O O O B O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O B O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O


A non-uniform multi-rate control strategy for a Markov chain-driven Networked Control System Cuenca Lacruz, ÁM.; Ojha, U.; Salt Llobregat, JJ.; Chow, M. (2015). In this work, a non-uniform multi-rate control strategy is applied to a kind of Networked Control System (NCS) where a wireless path tracking control for an Unmanned Ground Vehicle (UGV) is carried out. The main aims of the proposed strategy are to face time-varying network-induced delays and to avoid packet disorder. A Markov chain-driven NCS scenario will be considered, where different network load situations, and consequently, different probability density functions for the network delay are assumed. In order to assure mean-square stability for the considered NCS, a decay-rate based sufficient condition is enunciated in terms of probabilistic Linear Matrix Inequalities (LMIs). Simulation results show better control performance, and more accurate path tracking, for the scheduled (delay-dependent) controller than for the non-scheduled one (i.e. the nominal controller when delays appear). Finally, the control strategy is validated on an experimental test-bed. An NCS is a control system where different devices share a common communication link. Advantages such as cost reduction and easy maintenance have motivated a wide study about NCS in the last years (see, for instance, in [16] , [48] , [52] ). Nevertheless, some drawbacks arise when using a shared link, being the fundamental one the existence of time-varying delays when transmitting information between devices (usually, from sensor to controller and from controller to actuator) [51] , [47] , [24] , [7] . Also, in some cases, networks introduce packet dropouts [20] , [46] , [8] , packet disorder [32] , [8] , [53] , and bandwidth constraints [30] , [31] . Dealing at the same time with all the drawbacks involved in an NCS becomes a complex problem, and hence, some simplifying assumptions are usually made.. The present work is focused on facing time-varying network-induced delays and avoiding packet disorder in a kind of NCS where the plant to be wirelessly controlled is a UGV. Most of papers treating this scenario (for instance, [30] , [31] , [43] , [22] , [44] ) does not cope with the packet disorder phenomenon, and in addition, are characterized by:. • performing the main control tasks (that is, path tracking and delay compensation) at the remote side (with no direct communication to the plant).. At the local side (close to the plant), a simple PID is located to control the instantaneous rotational velocity.. • compensating for round-trip time delays from estimated remote-to-local delays (since at the remote side only the current local-to-remote delay is known).. • requiring estimated UGV states so as to generate the proper path references to be followed when the packets reach the local side. At this moment, the references are compared to the current, instantaneous velocities, and the consequent error signal is controlled by the simple PID.. The main problem of the approach considered in these papers is working with estimated values, since the worse the estimation is, the higher performance degradation could be. In order to avoid this problem, a proposal which deals with actual values for the round-trip time delays and the UGV states is proposed in the present work. This approach considers a Multi-Rate Input Control (MRIC) strategy [18] , [36] , [6] , [9] (i.e., the sensing rate is N times slower than the actuation rate), with the next features:. • the control tasks are separated into two control levels working at different rates: the path tracking control is located at the remote side generating slowrate references from the actual UGV state, and the delay compensation is situated at the local side generating a fast-rate control signal from the actual delay. Concretely, the path tracking controller implements a network-based adaptation of the Quadratic Curve (QC) algorithm by [49] , and the delay compensation controller applies a version of the gain scheduling approach introduced in [35] .. • the sensing period is chosen to be greater than the longest delay 2 . In this way, the packet disorder problem is avoided. But, from a single-rate control framework, this period could then be too great to reach the desired control performance (the greater the sampling period is, the worse the control performance should be expected [28] ). However, by adopting the MRIC strategy, since control actions are applied at N times faster rate than the sensing rate, the control performance can be maintained [3] , [19] .. • as a consequence of existing time-varying network delays, the fast-rate control signal will be non-uniformly applied, resulting in a non-uniform multirate control approach.. • actual round-trip time delays can be measured and compensated at the local side, since a local timer is shared by every local device. In addition, the remote controller needs no synchronization to develop its tasks, and hence no time-stamping techniques are required.. As a result of these features, our control proposal implies a straightforward implementation, being not required additional prediction stages for the delay and the UGV state (used in [30] , [31] , [43] , [22] , [44] ), and the possibility of reducing the network utilization (since information travels through the network at the slower rate).. The present work contemplates a Markov chain-driven NCS [21] , [10] , [33] , [38] , [39] , which is an special case of stochastic NCS [40] , [25] , [11] . Driving the NCS by a finite state Markov chain enables to consider not only states with different delay distributions (the stochastic case) but also transition probabilities among states. This kind of NCS model can be useful to be applied to most of Internet applications [26] , [41] . In an Internet environment is usual to find different network load scenarios, where heavy traffic situations can appear (loaded network) and disappear (unloaded network) following some transition probabilities. This will be the case considered in the present work. However, Markov chains can also be used to model other aspects of the NCS. For example, to drive activation states of subsets of actuators [13] , [14] , or subsets of sensors and actuators [15] , [23] . In any case, in order to assure stability in the jumping system, some conditions can be enunciated in terms of LMIs [5] under the consideration of transmission delays both in system output measurements and in control signals.. Summarizing, the paper includes the following sections. In section 2, the pro-Kinematics Event-based gain scheduling multi-rate controller Local side Remote side Fig. 1 . NCS scenario posed NCS is described. Section 3 presents the remote and local controllers. Then, in order to prove global mean-square asymptotical stability for the Markov chain-driven NCS, section 4 introduces a decay-rate based sufficient condition in terms of probabilistic LMIs. In addition, in this section, several cost functions are presented in order to be used when analyzing NCS performance. A simulation example in section 5 illustrates the main benefits of the control proposal, which is validated by means of an experimental test-bed in section 6. Finally, section 7 enumerates the main conclusions of the present work. In this work, a Markov chain-driven NCS is presented, where the plant to be wirelessly controlled is a UGV. The output sampling period can be chosen to be greater than the longest delay, avoiding the packet disorder phenomenon. Consequently, to improve dynamic control performance, multi-rate control techniques are used in such a way that the UGV is sensed at the long period (slow rate) and actuated at an N times shorter period (fast rate). The non-uniform multi-rate control system is decomposed into two sides: a remote side carrying out the path tracking control and generating slow-rate velocity references from UGV states, and a local side compensating for timevarying network-induced delays and converting the slow-rate references into fast-rate control actions, which are non-uniformly applied to the UGV. Eventbased controllers are implemented at both sides. Interesting advantages of the control proposal are the consideration of actual (not estimated) values for network delays and UGV states, a possible reduction of the network utilization, and a straightforward implementation.. Control system stability for the Markov chain-driven NCS is assured in terms of probabilistic LMIs. Simulation results point out the benefits of the proposed control strategy, which is validated on an experimental test-bed.

O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O


Per-Colorant-Channel Color Barcodes for Mobile Applications: An Interference Cancellation Framework Abstract-We propose a color barcode framework for mobile phone applications by exploiting the spectral diversity afforded by the cyan (C), magenta (M), and yellow (Y) print colorant channels commonly used for color printing and the complementary red (R), green (G), and blue (B) channels, respectively, used for capturing color images. Specifically, we exploit this spectral diversity to realize a three-fold increase in the data rate by encoding independent data in the C, M, and Y print colorant channels and decoding the data from the complementary R, G, and B channels captured via a mobile phone camera. To mitigate the effect of cross-channel interference among the printcolorant and capture color channels, we develop an algorithm for interference cancellation based on a physically-motivated mathematical model for the print and capture processes. To estimate the model parameters required for cross-channel interference cancellation, we propose two alternative methodologies: a pilot block approach that uses suitable selections of colors for the synchronization blocks and an expectation maximization approach that estimates the parameters from regions encoding the data itself. We evaluate the performance of the proposed framework using specific implementations of the framework for two of the most commonly used barcodes in mobile applications, QR and Aztec codes. Experimental results show that the proposed framework successfully overcomes the impact of the color interference, providing a low bit error rate and a high decoding rate for each of the colorant channels when used with a corresponding error correction scheme. The framework proposed in this paper provides an effective method for extending monochrome barcodes to color. Our color code constructions offer three times the data rates of their monochrome counterparts, exploiting the spectral diversity provided by color printing and capture systems in conjunction with model-based interference cancellation that mitigates inter-channel coupling introduced by the physical characteristics of the devices. Although, bit error rates and therefore information capacities vary across the three resulting channels, the error rates are in ranges that are readily handled by the error correction coding options available for monochrome barcodes. The framework described in this paper can easily be adapted to most monochrome barcode schemes using at least one and potentially either of the proposed approaches for estimating the interference cancellation parameters. Many existing 2-D barcodes inherently have localization patterns to efficiently locate the barcode in the captured image. In current monochrome designs these patterns are uniformly colored, but they can be easily modified to carry the pilot blocks of known colorant combinations that are required to estimate the interference cancellation parameters. This dual use of localization patterns, to also carry interference cancellation pilot blocks, is natural for typical mobile application codes such as the QR or Aztec codes, where the size of the localization patterns is large, relative to the barcode area. Even in situations where the size of localization patterns is small, for example Data Matrix, it is still possible to embed and extract correct color estimates [40] , [41] . For barcodes where this dual-use of the synchronization regions is either infeasible or undesirable, either our proposed EM-approach can be used to enable color interference cancellation without requiring the pilot blocks or, alternatively, part of the data field may be sacrificed and used to carry the pilot blocks. In this way, the data rate of any monochrome barcode can be tripled. In the appendix, we also evaluate the performance of the proposed EM-type color interference cancellation algorithm on the color barcodes recently proposed for high capacity barcode applications [10] , where data is extracted from a barcode scanned on a flatbed scanner. As the results show in the appendix, the proposed EM-style interference cancellation algorithm significantly improves the BER performance of these color barcodes proposed for high capacity barcode applications, validating the generality of the framework proposed in this paper.. A color barcode in the proposed framework can be directly deployed with existing camera phones without requiring any hardware modifications because camera phones already capture color images with three R, G, B channels. On the decoder side, the migration to the new code can therefore be enabled simply by a software upgrade of existing barcode reading applications or by developing a new reader application. The software modification required is also minimal since the technique used for data embedding in each of the channels is the same as the method currently used with monochrome barcodes and only the front-end synchronization processing needs modification. On the encoder side, color printing functionality is required in order to enable the proposed color barcode, which cannot be reproduced with black and white printers. This is not a significant limitation for the proposed barcodes because color is already common in printing for the most common 2-D mobile barcode application scenarios.. The additional capacity provided by the proposed framework through embedding independent data in the print colorant channels is most effective for advertisement applications in the business world. In these applications, our construction of color barcodes can be used to embed primary advertisement data, such as a URL, in one colorant channel, and additional tagging data in the other colorant channels. This additional information can identify the advertisement channel and venue, without compromising the capacity, robustness, and ease of use. Upon decoding by a suitable application on the mobile phone, the color barcode can then, not only connect the user's mobile phone to the website with additional information, but can also communicate the tagging information to a server that gathers data on how many of the QR codes in each of the advertisement channels were actually captured by mobile phone users. This information can be subsequently mined to determine the effectiveness of different display and print advertising channels providing useful input for pricing, advertisement placement, etc.. In a number of applications, the three layers (C, M, and Y print layers) in the proposed construction of color barcodes can be used to advantageously encode three separate pieces of information. For instance, each of the C, M, and Y layers may encode a URL, providing three different URLs. A mobile phone reader application can then offer a user who captures the color barcode, the option to choose amongst these three URLs, thereby providing quick and ready access to three pieces of online information, without requiring the user to navigate or click on their small mobile device. For instance, the three simultaneous URLs may provide the user an option to connect to either an overall company website, to a website of the local store where the advertised merchandise is available, or to the website of the publication where the advertisement appears. The fact that the three layers can be independently generated in our proposed barcode framework, provides very significant design flexibility, which is also advantageous. Whereas the decoding process for the three colorant layers is loosely coupled, it does not pose limitations for their use.. The proposed solution does have a few limitations. Color barcodes designed in the proposed framework cannot be read by a monochrome barcode reader and the barcodes can therefore be used only with a suitably designed decoder. While, as demonstrated in the experiments, color barcodes are well protected against errors, if a barcode is damaged or stained, all three channels may be equally affected. Although we have not observed significant influence of the printer type on barcode decoding, in many home or office color printers the yellow channel contains a random dot pattern that is used for identifying the printer for anticounterfeiting purposes [38] . The presence of these random patterns explains lower performance of the framework in yellow channel. Also it makes our scheme more suitable for professional, industrial applications where much more control over color management is provided, as opposed to small print centers.. Note that although the proposed construction of color barcodes achieves reasonably high decoding rates (typically higher than 50%), in some cases for a single image capture, they can not achieve the same decoding rate as the monochrome counterpart in all color channels. This however, is not a major problem because in many mobile applications a sequence of barcode images is captured, from which more than one frame can be used to extract the data in individual color channels.. In contrast with several other color barcode technologies that encode data in color, the proposed construction of color barcodes is significantly more robust to misregistration errors. Scanned RGB channels and estimated CMY channels after interference cancellation.. In the proposed construction of the color barcodes, independent data is encoded in print colorant layers and color interference cancellation is used at the decoder to overcome cross-channel coupling. This gives the method inherent robustness to mis-registration errors. While the layers may be misregistered, because the data is independently encoded and decoded from each layer it is robust against the misregistration, unlike other methods that rely on the color produced in combination of the overlay of the colorant layers (which changes with misregistration).

O B I O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O B I O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O B I O O O O O O B I O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O


A new image flux conduction model and its application to selective image smoothing Abstract-In this paper, a discrete image flux conduction equation which is completely new in this field is proposed. The new approach starts with formulating a discrete image flux conduction equation based on the concept of heat conduction theory. Based on this discrete equation, the status change at a time point can be directly computed from its spatial neighborhood. To more accurately estimate an image flux, we have used an orthogonal wavelet basis to approximate the gradient of the intensity at each point. Since the proposed approach is discrete by nature, it is not necessary to formulate a continuous PDE to fit the discrete image data set. Furthermore, introduction of different numerical methods to solve the PDE can also be avoided. Since the proposed approach does not require that a PDE be solved, it is therefore more efficient and accurate than the conventional methods. Experimental results obtained using both synthetic signals and real images have demonstrated that the proposed model could effectively handle the selective image smoothing problem. In this paper, we have derived a discrete image flux conduction equation from our proposed discrete image flux model using an image flux balance equation. Based on this discrete equation, the status change at a time point can be directly computed based on the image flux of its neighborhood. To more accurately estimate an image flux, we have used an orthogonal wavelet basis to approximate the gradient of the intensity at each point. We have also proved that our discrete equation, which is based on the orthogonal Haar wavelet basis, satisfies the so-called maximum and minimum principle. Experimental results obtained using both synthetic signals and real images have demonstrated that the proposed model could effectively handle the selective image smoothing problem. Let be a periodical function on (1, ) [29] . Therefore, and . Thus, (48) can be written as follows:. That is Therefore, (10) satisfies the average grey level invariance property.

O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O


Synthetic biology: ensuring the greatest global value Abstract Synthetic biology (SynBio) has tremendous, transformative potential. Like other technologies, it can be used for good or ill. Currently, the structure of the allocation of potential benefits and risks is biased in favor of richer countries. The underlying problem is simple: most risks from SynBio are universal and affect both the rich and the poor with equal force; but benefits from SynBio can be expected to accrue chiefly to the rich. The risk/benefit balance is therefore skewed in a way that may lead to inefficient and unfair decisions. One potential solution is presented in this paper, using the principles that underlie the Health Impact Fund (HIF). The HIF is designed to reward companies based on assessed health impact, no matter where it occurs in the world, so that extending the life of a poor person is as profitable as extending the life of a rich person. This paper considers both the potential benefits and costs of SynBio; examines how the current global pharmaceutical industry is structured; introduces the HIF proposal; and finally explores how the principles underlying the HIF could be used productively with SynBio for global health. Synthetic biology (SynBio) has tremendous, transformative potential. Like other technologies, it can be used for good or ill. Currently, the structure of the allocation of potential benefits and risks is biased in favor of richer countries. The underlying problem is simple: most risks from SynBio are universal and affect both the rich and the poor with equal force; but benefits from SynBio can be expected to accrue chiefly to the rich. The risk/benefit balance is therefore skewed in a way that may lead to inefficient and unfair decisions. One potential solution is presented in this paper, using the principles that underlie the Health Impact Fund (HIF). The HIF is designed to reward companies based on assessed health impact, no matter where it occurs in the world, so that extending the life of a poor person is as profitable as extending the life of a rich person. This paper considers both the potential benefits and costs of SynBio; examines how the current global pharmaceutical industry is structured; introduces the HIF proposal; and finally explores how the principles underlying the HIF would interact productively with SynBio.

O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O B


A Study of Inherent Pen Input Modalities for Precision Parameter Manipulations during Trajectory Tasks Adjustment of a certain parameter in the course of performing a trajectory task such as drawing or gesturing is a common manipulation in pen-based interaction. Since pen tip information is confined to x-y coordinate data, such concurrent parameter adjustment is not easily accomplished in devices using only a pen tip. This paper comparatively investigates the performance of inherent pen input modalities (Pressure, Tilt, Azimuth, and Rolling) and Key Pressing with the non-preferred hand used for precision parameter manipulation during pen sliding actions. We elaborate our experimental design framework here and conduct experimentation to evaluate the effect of the five techniques. Results show that Pressure enabled the fastest performance along with the lowest error rate, while Azimuth exhibited the worst performance. Tilt showed slightly faster performance and achieved a lower error rate than Rolling. However, Rolling achieved the most significant learning effect on Selection Time and was favored over Tilt in subjective evaluations. Our experimental results afford a general understanding of the performance of inherent pen input modalities in the course of a trajectory task in HCI (human computer interaction). key words: human computer interaction, pen input, inherent pen input modalities, multi-scale navigation, pen-based interfaces In pen-based user interfaces, adjustment of a parameter as well as its granularity, or manipulation of a value besides x-y cursor movement, is usually required, such as changing a rectangle's scale with different levels of granularity and adjusting the color of a line while drawing. However, compared with that of other input devices such as keyboards and mice, the input throughput capacity of pens is less because the pen input channel is restricted to x-y coordinate data. Thus it is generally difficult to use the pen to adjust both a parameter and the granularity without other input modalities.. In this background, research has been conducted on the use of inherent pen input modalities such as pen pressure, tilt, azimuth and rolling to enhance the pen input capacity. Some of these studies, for example [1] , focused on human ability to control these modalities, while others, for example [2] , designed novel interaction techniques based on the pen modalities. However, most of these studies investigated only one or two pen input modalities. In particular, regarding precision parameter manipulation, only performance using pen pressure has been investigated [3] . Utilization of other inherent pen input modalities to achieve precision pa- rameter manipulation during trajectory task remains unexplored. This gap in the literature motivates us to systematically evaluate performance using pen input modalities to realize precision parameter manipulations during trajectory tasks.. In this study, four kinds of inherent pen input modalities, Pressure, Tilt, Azimuth, and Rolling, used for highprecision parameter manipulation were comparatively investigated by both qualitative and quantitative analysis. Here Pressure means the pressure exerted on the stylus pen tip by the user. Tilt means the angle between the tablet surface and the pen body. Azimuth is the angle from the north direction on the tablet surface to the vertical projection of the pen on the tablet surface. Rolling means the angle the user rolls the pen around its longitudinal axis. Figure 1 is a schematic diagram of these pen input modalities.. We conducted experimentation to evaluate the performance of these pen modalities and compared them with Key Pressing using the non-preferred hand. We elaborate the experimental design, present the results, and discuss the advantages and disadvantages of each pen modality. This paper provides pen-based interface designers with a general understanding of pen input modality choice for precision parameter manipulation during trajectory tasks. In this paper, four kinds of inherent pen input modalities (Pressure, Tilt, Azimuth, and Rolling) used for high precision parameter manipulation during pen sliding were comparatively investigated. We conducted an experiment to evaluate their performance and compared them with Key Pressing using the non-preferred hand. Our results indicate that subjects performed fastest and with the fewest errors when using Pressure. However, performance with Azimuth was the worst, and subjects evaluated Azimuth as unsuitable for the experimental tasks because of it conflicted with their pen use habits. Tilt showed slightly faster performance and achieved lower error rate than Rolling. Moreover, Tilt achieved the lowest error rate in some Width and Distance conditions. Nevertheless, participant performance improved the most with Rolling, and Rolling was favored over Tilt in subjective evaluations. Our experimental results verify the feasibility of concurrent pen manipulations based on pen input modalities and provide pen-based interface designers with a general understanding of pen input modality choice for precision parameter manipulation during trajectory tasks. According to the quantitative measures (Selection Time, Error Rate, Number of Crossings, and Effective Width) and subjective evaluations, Pressure enabled the fastest performance and, remarkably, even surpassed bimanual manipulation. Adjusting a parameter while sliding the pen is a common manipulation in pen-based interaction, so even tiny improvements may result in significant benefits to users. On the other hand, although performance of inherent pen input modalities other than Pressure did not surpass bimanual manipulation, they did have specific advantages. As well, the non-preferred-hand-free concurrent manipulation was positively rated by users, preferred to bimanual manipulation. This experiment took an average of 1.16 hours per participant. After each block, subjects were allowed an optional 10-minute break. Literature related to pen pressure emerged mainly after the new Millennium, and most of them focused on novel interaction technique designs. Mizuno et al. [4] implemented a virtual sculpting system by converting pen pressure to carving depth and angle. Ramos et al. [2] proposed a concept prototype designed for use with pressure-sensitive digitizer tablets to fluidly navigate, segment, link, and annotate digiCopyright c 2009 The Institute of Electronics, Information and Communication Engineers tal videos; created the Zlider [3] that users can use pen pressure to achieve fluid zooming while sliding the pen; and developed pressure marks [5] that allowed users to perform a selection and an action simultaneously by stroking the pen and changing the pen pressure at the same time. Similarly, Harada et al. [6] used pen pressure as an input modal to augment simultaneous input capacity. Ren et al. [7] proposed the Adaptive Hybrid Cursor to facilitate the target selection tasks by automatically adapting the size of the cursor based on pen pressure input. Yin and Ren [8] proposed a zoombased technique to improve pixel-target selection, in which the pressure is used as a mode switch.. There were also some published studies that focused on pen pressure characteristics and/or explored the human ability to control pen pressure. Ramos et al. [1] investigated the human ability to perform discrete selection tasks by controlling stylus pressure and found that dividing pressure space into 6 levels resulted in optimal controllability. Li et al. [9] investigated five techniques for switching between ink and gesture modes in pen interfaces, including a pen pressure based mode switching technique that allowed implicit mode transitions. Zhou et al. [10] comparatively investigated the performance of pen pressure and tilt in a cursor control experiment.. Compared to the studies on pen pressure, few studies that focused on the exploration of pen tilt, azimuth, and rolling were found. Tilt Cursor [11] provided users with 3D pen orientation as visual cues. Another technique, Tilt Menu [12] , extended the selection capabilities of pen-based user interfaces using 3D pen orientation information. Oshita [13] designed a virtual human figure movement manipulation system that used not only pen pressure but also pen tilt to control a virtual human figure. Bi et al. [14] explored pen rolling around the longitudinal axis of the pen and determined the intentional and incidental pen rolling while users manipulating a pen.. Although the aforementioned works explored the utilization of pen input modalities to widen the stylus input vocabulary available to the user, only two are close to our current inquiry. One, the Zlider [3] , is a high precision parameter mechanism for fluid integrated manipulation of zooming via pen pressure input during pen sliding. But a major different point from this study is that their study only employed pen pressure modality, while this study fully investigated four different pen input modalities. The other study [10] , evaluated cursor control from pen input modalities with the pen tip stationary, while this study focuses on precision parameter manipulation with the pen tip moving, which should have broader relevance to practical utilization of digital pens.

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