10,415 research outputs found

    Automated Hierarchical Image Segmentation Based on Merging of Quadrilaterals

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    Proceedings of the 6th WSEAS International Conference on Signal Processing, Computational Geometry & Artifical Vision, 2006, p. 135-140This paper proposes a quadrilateral-based and automated hierarchical segmentation method, in which quadrilaterals are first constructed from an edge map, where neighboring quadrilaterals with similar features of interest are then merged together in a hierarchical mode to form regions. When evaluated qualitatively and quantitatively, the proposed method outperforms three traditional and commonly-used techniques, namely, K-means clustering, seeded region growing and quadrilateral-based segmentation. It is shown by experimental results that our proposed method is robust in both recovering missed important regions while preventing unnecessary over-segmentation, and offers an efficient description of the segmented objects conducive to content-based applications.postprintThe 6th WSEAS International Conference on Signal Processing, Computational Geometry & Artificial Vision (ISCGAV'06), Crete, Greece, August 2006. in Conference Proceedings, 2006, p. 135-14

    Object-Based Rendering and 3D reconstruction Using a Moveable Image-Based System

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    Image-based rendering of ancient Chinese artifacts for multi-view displays - a multi-camera approach

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    Image-based rendering (IBR) is an emerging and promising technology for photo-realistic rendering of scenes and objects from a collection of densely sampled images and videos. This paper proposes an image-based approach to the rendering and multi-view display of ancient Chinese artifacts for cultural heritage preservation. A multiple-camera circular array was constructed to record images of the artifacts. Novel techniques for segmenting and rendering new views of the artifacts from the sampled images are developed. The multiple views so synthesized enable the ancient artifacts to be displayed in modern multi-view displays and conventional stereo systems. Several collections from the University Museum and Art Gallery at the University of Hong Kong are captured and excellent rendering results are obtained. ©2010 IEEE.published_or_final_versionThe 2010 IEEE International Symposium on Circuits and Systems (ISCAS), Paris, France, 30 May-2 June 2010. In IEEE International Symposium on Circuits and Systems Proceedings, 2010, p. 3252-325

    A multi-camera approach to image-based rendering and 3-D/Multiview display of ancient chinese artifacts

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    Suppression of Vascular Endothelial Growth Factor via Inactivation of Eukaryotic Elongation Factor 2 by Alkaloids in Coptidis rhizoma in Hepatocellular Carcinoma

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    Aim of study: To investigate the inhibitory effect of Coptidis rhizome aqueous extract (CRAE) on vascular endothelial growth factor (VEGF) expression and tumor angiogenesis in hepatocellular carcinoma (HCC). Methods: Quality control of CRAE was determined. Secretion of VEGF protein and expression of its mRNA in MHCC97L and Hep G2 cells were measured with enzyme-linked immunosorbent assay and quantitative real-time polymerase chain reaction. Synthesis of nascent protein was determined by AHA-protein-labeling technologies. The in vivo antiangiogenic effect of CRAE was evaluated with a xenograft model. Results: Absence of organochlorine pesticides in CRAE was found, and phytochemical analysis showed that its components were in proportion of magnoflorine 2.2%, jatrorrhizine 1.68%, palmatine 4.4%, and berberine 13.8%. CRAE exhibited significant inhibition on VEGF secretion from MHCC97L and HepG2 cells at nontoxic doses. The mRNA transcripts of VEGF could not be inhibited by CRAE; however, synthesis of VEGF nascent protein was potently blocked by CRAE. CRAE intervention increased the phosphorylation of eukaryotic elongation factor 2 (eEF2) in HCC cells, which blocked eEF2 activity for proceeding nascent protein synthesis. The activity of eEF2 was restored in CRAE-treated HCC cells in the presence of A484594, leading to the recovery of VEGF expression. Berberine was found to be the major active component in CRAE; however, CRAE is more effective in inhibiting eEF2 activity compared to berberine treatment alone, suggesting the additive effect of other components present. Reduction of tumor size and neovascularization were observed in mice xenograft model. Conclusion: Our study postulates the antiangiogenic effect of CRAE on hepatocellular carcinoma via an eEF2-driven pathway.postprin

    Slow cooling and efficient extraction of C-exciton hot carriers in MoS2 monolayer

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    In emerging optoelectronic applications, such as water photolysis, exciton fission and novel photovoltaics involving low-dimensional nanomaterials, hot-carrier relaxation and extraction mechanisms play an indispensable and intriguing role in their photo-electron conversion processes. Two-dimensional transition metal dichalcogenides have attracted much attention in above fields recently; however, insight into the relaxation mechanism of hot electron-hole pairs in the band nesting region denoted as C-excitons, remains elusive. Using MoS2 monolayers as a model two-dimensional transition metal dichalcogenide system, here we report a slower hot-carrier cooling for C-excitons, in comparison with band-edge excitons. We deduce that this effect arises from the favourable band alignment and transient excited-state Coulomb environment, rather than solely on quantum confinement in two-dimension systems. We identify the screening-sensitive bandgap renormalization for MoS2 monolayer/graphene heterostructures, and confirm the initial hot-carrier extraction for the C-exciton state with an unprecedented efficiency of 80%, accompanied by a twofold reduction in the exciton binding energy

    A Fuzzy Social Network Analysis Method and a Case Study on Tianya

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    Social networking service (SNS) has become online service platforms that focus on facilitating the building of social networks among people who share interests, activities, backgrounds, or real-life connections and has had a rapid development in China in the past few years. This paper aims to develop a fuzzy social network service analysis method, which combines graph theory with related fuzzy approach, to analyze the social network structural features and the distribution characteristics of interpersonal nodes in SNS community. A case study on a very famous Chinese tourism BBS-Tianya-is conducted to illustrate and validate the proposed approach. The research findings are as follows: (1) The attraction degrees of various areas in the forum are significantly different; (2) interpersonal nodes in the forum are concentrated relatively; (3) the fuzzy out-degrees and the fuzzy in-degrees of interpersonal nodes in the forum conflict each other; and (4) the distribution of interpersonal nodes is influenced by geographical relations. These findings can directly support social network service management and particularly tourism online service developments. © Springer-Verlag Berlin Heidelberg 2014

    The design and construction of a movable image-based rendering system and its application to multiview conferencing

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    Image-based rendering (IBR) is an promising technology for rendering photo-realistic views of scenes from a collection of densely sampled images or videos. It provides a framework for developing revolutionary virtual reality and immersive viewing systems. While there has been considerable progress recently in the capturing, storage and transmission of image-based representations, most multiple camera systems are designed to be stationary and hence their ability to cope with moving objects and dynamic environment is somewhat limited. This paper studies the design and construction of a movable image-based rendering system based on a class of dynamic representations called plenoptic videos, its associated video processing algorithms and an application to multiview audio-visual conferencing. It is constructed by mounting a linear array of 8 video cameras on an electrically controllable wheel chair and its motion is controllable manually or remotely through wireless LAN by means of additional hardware circuitry. We also developed a real-time object tracking algorithm and utilize the motion information computed to adjust continuously the azimuth or rotation angle of the movable IBR system in order to cope with a given moving object in a large environment. Due to imperfection in tracking and mechanical vibration encountered in movable systems, the videos may appear very shaky and a new video stabilization technique is proposed to overcome this problem. The usefulness of the system is illustrated by means of a multiview conferencing application using a multiview TV display. Through this pilot study, we hope to disseminate useful experience for the design and construction of movable IBR systems with improved viewing freedom and ability to cope with moving object in a large environment.published_or_final_versio
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