The Experts below are selected from a list of 33747 Experts worldwide ranked by ideXlab platform
Qi Tian - One of the best experts on this subject based on the ideXlab platform.
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Picture-in-picture copy detection using Spatial Coding techniques
Proceedings of the 2011 ACM international workshop on Automated media analysis and production for novel TV services - AIEMPro '11, 2011Co-Authors: Sanjay Purushotham, Qi Tian, C.-c. Jay KuoAbstract:Picture-in-Picture (PiP) is a special video transformation where one or more videos is scaled and Spatially embedded in a host video. PiP is a very useful service to watch two or more videos simultaneously, however it can be exploited to visually hide one video inside another video. Today's copy detection techniques can be easily fooled by PiP, which is reflected in the poor results in the yearly TRECVID competitions. Inspired by the promise of Spatial Coding in partial image matching, we propose a generalized Spatial Coding representation in which both the relative position and relative orientation is embedded in the Spatial code. In this paper, we will provide novel formulation for Spatial verification problem and introduce polynomial and non-polynomial algorithms to efficiently address the Spatial verification problem. Our initial experiment results on TRECVID and MSRA datasets shows that our proposed Spatial verification algorithms provide around 20% improvement over the classical hierarchical bag-of-words approach.
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Spatial Coding for large scale partial duplicate web image search
ACM Multimedia, 2010Co-Authors: Wengang Zhou, Yibing Song, Qi TianAbstract:The state-of-the-art image retrieval approaches represent images with a high dimensional vector of visual words by quantizing local features, such as SIFT, in the descriptor space. The geometric clues among visual words in an image is usually ignored or exploited for full geometric verification, which is computationally expensive. In this paper, we focus on partial-duplicate web image retrieval, and propose a novel scheme, Spatial Coding, to encode the Spatial relationships among local features in an image. Our Spatial Coding is both efficient and effective to discover false matches of local features between images, and can greatly improve retrieval performance. Experiments in partial-duplicate web image search, using a database of one million images, reveal that our approach achieves a 53% improvement in mean average precision and 46% reduction in time cost over the baseline bag-of-words approach.
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ACM Multimedia - Spatial Coding for large scale partial-duplicate web image search
Proceedings of the international conference on Multimedia - MM '10, 2010Co-Authors: Wengang Zhou, Yibing Song, Qi TianAbstract:The state-of-the-art image retrieval approaches represent images with a high dimensional vector of visual words by quantizing local features, such as SIFT, in the descriptor space. The geometric clues among visual words in an image is usually ignored or exploited for full geometric verification, which is computationally expensive. In this paper, we focus on partial-duplicate web image retrieval, and propose a novel scheme, Spatial Coding, to encode the Spatial relationships among local features in an image. Our Spatial Coding is both efficient and effective to discover false matches of local features between images, and can greatly improve retrieval performance. Experiments in partial-duplicate web image search, using a database of one million images, reveal that our approach achieves a 53% improvement in mean average precision and 46% reduction in time cost over the baseline bag-of-words approach.
Wengang Zhou - One of the best experts on this subject based on the ideXlab platform.
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Spatial Coding for large scale partial duplicate web image search
ACM Multimedia, 2010Co-Authors: Wengang Zhou, Yibing Song, Qi TianAbstract:The state-of-the-art image retrieval approaches represent images with a high dimensional vector of visual words by quantizing local features, such as SIFT, in the descriptor space. The geometric clues among visual words in an image is usually ignored or exploited for full geometric verification, which is computationally expensive. In this paper, we focus on partial-duplicate web image retrieval, and propose a novel scheme, Spatial Coding, to encode the Spatial relationships among local features in an image. Our Spatial Coding is both efficient and effective to discover false matches of local features between images, and can greatly improve retrieval performance. Experiments in partial-duplicate web image search, using a database of one million images, reveal that our approach achieves a 53% improvement in mean average precision and 46% reduction in time cost over the baseline bag-of-words approach.
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ACM Multimedia - Spatial Coding for large scale partial-duplicate web image search
Proceedings of the international conference on Multimedia - MM '10, 2010Co-Authors: Wengang Zhou, Yibing Song, Qi TianAbstract:The state-of-the-art image retrieval approaches represent images with a high dimensional vector of visual words by quantizing local features, such as SIFT, in the descriptor space. The geometric clues among visual words in an image is usually ignored or exploited for full geometric verification, which is computationally expensive. In this paper, we focus on partial-duplicate web image retrieval, and propose a novel scheme, Spatial Coding, to encode the Spatial relationships among local features in an image. Our Spatial Coding is both efficient and effective to discover false matches of local features between images, and can greatly improve retrieval performance. Experiments in partial-duplicate web image search, using a database of one million images, reveal that our approach achieves a 53% improvement in mean average precision and 46% reduction in time cost over the baseline bag-of-words approach.
Antonio Fernández-ruiz - One of the best experts on this subject based on the ideXlab platform.
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Subcircuits of Deep and Superficial CA1 Place Cells Support Efficient Spatial Coding across Heterogeneous Environments.
Neuron, 2020Co-Authors: Farnaz Sharif, Behnam Tayebi, György Buzsáki, Sébastien Royer, Antonio Fernández-ruizAbstract:The hippocampus is thought to guide navigation by forming a cognitive map of space. Different environments differ in geometry and the availability of cues that can be used for navigation. Although several Spatial Coding mechanisms are known to coexist in the hippocampus, how they are influenced by various environmental features is not well understood. To address this issue, we examined the Spatial Coding characteristics of hippocampal neurons in mice and rats navigating in different environments. We found that CA1 place cells located in the superficial sublayer were more active in cue-poor environments and preferentially used a firing rate code driven by intra-hippocampal inputs. In contrast, place cells located in the deep sublayer were more active in cue-rich environments and used a phase code driven by entorhinal inputs. Switching between these two Spatial Coding modes was supported by the interaction between excitatory gamma inputs and local inhibition.
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Subcircuits of deep and superficial CA1 place cells support efficient Spatial Coding across heterogeneous environments
2020Co-Authors: Farnaz Sharif, Behnam Tayebi, György Buzsáki, Sébastien Royer, Antonio Fernández-ruizAbstract:The hippocampus is thought to guide navigation by forming a cognitive map of space. However, the behavioral demands for such a map can vary depending on particular features of a given environment. For example, an environment rich in cues may require a finer resolution map than an open space. It is unclear how the hippocampal cognitive map adjusts to meet these distinct behavioral demands. To address this issue, we examined the Spatial Coding characteristics of hippocampal neurons in mice and rats navigating different environments. We found that CA1 place cells located in the superficial sublayer were more active in cue-poor environments, and preferentially used a firing rate code driven by intra-hippocampal inputs. In contrast, place cells located in the deep sublayer were more active in cue-rich environments and expressed a phase code driven by entorhinal inputs. Switching between these two Spatial Coding modes was supported by the interaction between excitatory gamma inputs and local inhibition.
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Spatial Coding and physiological properties of hippocampal neurons in the Cornu Ammonis subregions.
Hippocampus, 2016Co-Authors: Azahara Oliva, György Buzsáki, Antonio Fernández-ruiz, Antal BerényiAbstract:It is well-established that the feed-forward connected main hippocampal areas, CA3, CA2, and CA1 work cooperatively during Spatial navigation and memory. These areas are similar in terms of the prevalent types of neurons; however, they display different Spatial Coding and oscillatory dynamics. Understanding the temporal dynamics of these operations requires simultaneous recordings from these regions. However, simultaneous recordings from multiple regions and subregions in behaving animals have become possible only recently. We performed large-scale silicon probe recordings simultaneously spanning across all layers of CA1, CA2, and CA3 regions in rats during Spatial navigation and sleep and compared their behavior-dependent spiking, oscillatory dynamics and functional connectivity. The accuracy of place cell Spatial Coding increased progressively from distal to proximal CA1, suddenly dropped in CA2, and increased again from CA3a toward CA3c. These variations can be attributed in part to the different entorhinal inputs to each subregions, and the differences in theta modulation of CA1, CA2, and CA3 neurons. We also found that neurons in the subregions showed differences in theta modulation, phase precession, state-dependent changes in firing rates and functional connectivity among neurons of these regions. Our results indicate that a combination of intrinsic properties together with distinct intra- and extra-hippocampal inputs may account for the subregion-specific modulation of spiking dynamics and Spatial tuning of neurons during behavior. © 2016 Wiley Periodicals, Inc.
Isabel Arend - One of the best experts on this subject based on the ideXlab platform.
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Social priming of hemiSpatial neglect affects Spatial Coding: Evidence from the Simon task.
Consciousness and cognition, 2016Co-Authors: Isabel Arend, Daniela Aisenberg, Avishai HenikAbstract:Abstract In the Simon effect (SE), choice reactions are fast if the location of the stimulus and the response correspond when stimulus location is task-irrelevant; therefore, the SE reflects the automatic processing of space. Priming of social concepts was found to affect automatic processing in the Stroop effect. We investigated whether Spatial Coding measured by the SE can be affected by the observer’s mental state. We used two social priming manipulations of impairments: one involving Spatial processing - hemiSpatial neglect (HN) and another involving color perception - achromatopsia (ACHM). In two experiments the SE was reduced in the “neglected” visual field (VF) under the HN, but not under the ACHM manipulation. Our results show that Spatial Coding is sensitive to Spatial representations that are not derived from task-relevant parameters, but from the observer’s cognitive state. These findings dispute stimulus-response interference models grounded on the idea of the automaticity of Spatial processing.
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Spatial Coding as a Function of Handedness and Responding Hand: Theoretical and Methodological Implications.
PloS one, 2016Co-Authors: Isabel Arend, Peter H. Weiss, David C. Timpert, Gereon R. Fink, Avishai HenikAbstract:The Simon effect shows that choice reactions are faster if the location of the stimulus and the response correspond, even when stimulus location is task-irrelevant. The Simon effect raises the question of what factors influence Spatial Coding. Until now, the effects of handedness, responding hand, and visual field were addressed in separate studies that used bimanual and unimanual tasks, providing inconclusive results. Here we aimed to close this empirical gap by looking at the effects of these variables in the same study. We used a unimanual version of a Simon task with four groups of participants: left-handed and right-handed, responding with the dominant or nondominant hand. Our results show that the Simon effect is substantially reduced in the field of the responding hand for all groups of participants, except for left-handed individuals responding with the left-hand. These findings highlight the importance of attention mechanisms in stimulus-response Coding. They reflect that stimulus-response interference is influenced by hierarchical activation of response units. At a practical level, these findings call for a number of methodological considerations (e.g., handedness, responding hand, and visual field) when using stimulus-response conflict to address Spatial Coding and cognitive control functions in neurological populations.
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Numerical-Spatial representation affects Spatial Coding: binding errors across the numerical distance effect
Psychonomic bulletin & review, 2013Co-Authors: Isabel Arend, Sharon Naparstek, Avishai HenikAbstract:Does numerical-Spatial representation affect fea- ture binding? Studies of visual attention show that poor Spatial Coding leads to illusory conjunctions (ICs). In nu- merical cognition, it has been shown that numbers and space are not totally dissociated. This association underlies the numerical distance effect (DE): faster responses as the dis- tance between the compared digits becomes larger (2 7 vs. 2 4). We used the DE to test whether numerical-Spatial repre- sentation is available to visual processes that rely on Spatial Coding, such as feature binding. Participants reported the larger of two colored numbers. Both numerical distance (distances 2 and 5) and number-space congruity (e.g., con- gruent pair, 1 3; incongruent pair, 3 1) were analyzed. Re- sults showed a higher proportion of ICs for distance 2 than for distance 5, providing strong evidence that numerical- Spatial representation (1) entails a strong location code and (2) is available to visual processes that rely on location information.
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An object-based frame of reference within the human pulvinar.
Brain, 2007Co-Authors: Robert Ward, Isabel ArendAbstract:The pulvinar nucleus of the thalamus is massively interconnected to cortical areas which translate Spatial visual information into coordinate systems defined by multiple reference frames [Grieve et al. (The primate pulvinar nuclei: vision and action. Trends in Neurosciences 2000; 23 (1): 35–39)]. Here we report the first evidence that Spatial Coding in the pulvinar is defined by an object-based frame. We evaluated the efficiency of Spatial Coding in two patients with damage to Spatial maps within the pulvinar. Patients located targets within a 2 × 2 (up/down × left/right) search array, which was itself located within a 2 × 2 retinotopic space. For both patients, Spatial deficits were defined in both a retinotopic and an object-based frame. For example, targets in the contralesional side of the array were poorly localized whether the array appeared in contra or ipsilesional retinotopic space. We conclude that Spatial processing bias following pulvinar damage can be defined by coordinate systems based on both object-based and retinotopic spaces.
Avishai Henik - One of the best experts on this subject based on the ideXlab platform.
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Social priming of hemiSpatial neglect affects Spatial Coding: Evidence from the Simon task.
Consciousness and cognition, 2016Co-Authors: Isabel Arend, Daniela Aisenberg, Avishai HenikAbstract:Abstract In the Simon effect (SE), choice reactions are fast if the location of the stimulus and the response correspond when stimulus location is task-irrelevant; therefore, the SE reflects the automatic processing of space. Priming of social concepts was found to affect automatic processing in the Stroop effect. We investigated whether Spatial Coding measured by the SE can be affected by the observer’s mental state. We used two social priming manipulations of impairments: one involving Spatial processing - hemiSpatial neglect (HN) and another involving color perception - achromatopsia (ACHM). In two experiments the SE was reduced in the “neglected” visual field (VF) under the HN, but not under the ACHM manipulation. Our results show that Spatial Coding is sensitive to Spatial representations that are not derived from task-relevant parameters, but from the observer’s cognitive state. These findings dispute stimulus-response interference models grounded on the idea of the automaticity of Spatial processing.
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Spatial Coding as a Function of Handedness and Responding Hand: Theoretical and Methodological Implications.
PloS one, 2016Co-Authors: Isabel Arend, Peter H. Weiss, David C. Timpert, Gereon R. Fink, Avishai HenikAbstract:The Simon effect shows that choice reactions are faster if the location of the stimulus and the response correspond, even when stimulus location is task-irrelevant. The Simon effect raises the question of what factors influence Spatial Coding. Until now, the effects of handedness, responding hand, and visual field were addressed in separate studies that used bimanual and unimanual tasks, providing inconclusive results. Here we aimed to close this empirical gap by looking at the effects of these variables in the same study. We used a unimanual version of a Simon task with four groups of participants: left-handed and right-handed, responding with the dominant or nondominant hand. Our results show that the Simon effect is substantially reduced in the field of the responding hand for all groups of participants, except for left-handed individuals responding with the left-hand. These findings highlight the importance of attention mechanisms in stimulus-response Coding. They reflect that stimulus-response interference is influenced by hierarchical activation of response units. At a practical level, these findings call for a number of methodological considerations (e.g., handedness, responding hand, and visual field) when using stimulus-response conflict to address Spatial Coding and cognitive control functions in neurological populations.
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Numerical-Spatial representation affects Spatial Coding: binding errors across the numerical distance effect
Psychonomic bulletin & review, 2013Co-Authors: Isabel Arend, Sharon Naparstek, Avishai HenikAbstract:Does numerical-Spatial representation affect fea- ture binding? Studies of visual attention show that poor Spatial Coding leads to illusory conjunctions (ICs). In nu- merical cognition, it has been shown that numbers and space are not totally dissociated. This association underlies the numerical distance effect (DE): faster responses as the dis- tance between the compared digits becomes larger (2 7 vs. 2 4). We used the DE to test whether numerical-Spatial repre- sentation is available to visual processes that rely on Spatial Coding, such as feature binding. Participants reported the larger of two colored numbers. Both numerical distance (distances 2 and 5) and number-space congruity (e.g., con- gruent pair, 1 3; incongruent pair, 3 1) were analyzed. Re- sults showed a higher proportion of ICs for distance 2 than for distance 5, providing strong evidence that numerical- Spatial representation (1) entails a strong location code and (2) is available to visual processes that rely on location information.