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IEEE International Symposium on Circuits and Systems

作者： Hsuan-Tsung Wang Walter D. Leon-Salas Computer Science Electrical Eng. Dept. University of Missouri-Kansas City Kansas City MO USA

ISBN: (纸本)9781467302180

An image compression algorithm suitable for focal plane integration and its hardware implementation are presented. In this approach an image is progressively decomposed into images of lower resolution. The low resolution images are then used as the predictors of the higher resolution images. The prediction residuals are entropy encoded and compressed. This compression approach can provide lossless or lossy compression and the resulting bitstream is a fully embedded code. A switched-capacitor circuit is proposed to implement the required operations. A prototype has been implemented on a 0.5 μm CMOS process. Simulation and measurements results validating the proposed approach are reported.

关键词： Image coding Image resolution Capacitors Entropy CMOS integrated circuits predictive coding Clocks

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predictive coding: An account of the mirror neuron system

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Cognitive Processing 2007年第3期8卷 159-166页

作者： Kilner, James M. Friston, Karl J. Frith, Chris D. Wellcome Trust Centre for Neuroimaging Institute of Neurology London WC1N 3BG 12 Queen Square United Kingdom

Is it possible to understand the intentions of other people by simply observing their actions? Many believe that this ability is made possible by the brain's mirror neuron system through its direct link between action and observation. However, precisely how intentions can be inferred through action observation has provoked much debate. Here we suggest that the function of the mirror system can be understood within a predictive coding framework that appeals to the statistical approach known as empirical Bayes. Within this scheme the most likely cause of an observed action can be inferred by minimizing the prediction error at all levels of the cortical hierarchy that are engaged during action observation. This account identifies a precise role for the mirror system in our ability to infer intentions from actions and provides the outline of the underlying computational mechanisms. © 2007 Marta Olivetti Belardinelli and Springer-Verlag.

关键词： Action observation Bayesian inference Mirror neurons predictive coding

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Action understanding and active inference

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BIOLOGICAL CYBERNETICS 2011年第1-2期104卷 137-160页

作者： Friston, Karl J. Mattout, Jeremie Kilner, James UCL Inst Neurol Wellcome Trust Ctr Neuroimaging London WC1N 3BG England INSERM U821 F-69008 Lyon France

We have suggested that the mirror-neuron system might be usefully understood as implementing Bayes-optimal perception of actions emitted by oneself or others. To substantiate this claim, we present neuronal simulations that show the same representations can prescribe motor behavior and encode motor intentions during action-observation. These simulations are based on the free-energy formulation of active inference, which is formally related to predictive coding. In this scheme, (generalised) states of the world are represented as trajectories. When these states include motor trajectories they implicitly entail intentions (future motor states). Optimizing the representation of these intentions enables predictive coding in a prospective sense. Crucially, the same generative models used to make predictions can be deployed to predict the actions of self or others by simply changing the bias or precision (i.e. attention) afforded to proprioceptive signals. We illustrate these points using simulations of handwriting to illustrate neuronally plausible generation and recognition of itinerant (wandering) motor trajectories. We then use the same simulations to produce synthetic electrophysiological responses to violations of intentional expectations. Our results affirm that a Bayes-optimal approach provides a principled framework, which accommodates current thinking about the mirror-neuron system. Furthermore, it endorses the general formulation of action as active inference.

关键词： Action-observation Mirror-neuron system Inference Precision Free-energy Perception Generative models predictive coding

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Reversible data hiding based on histogram modification of prediction-error

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IMAGING SCIENCE JOURNAL 2011年第5期59卷 278-292页

作者： Lee, C-F Chen, H-L Chaoyang Univ Technol Dept Informat Management Taichung 41349 Taiwan Chaoyang Univ Technol Doctoral Program Grad Inst Informat Taichung 41349 Taiwan

This work presents a novel histogram-based reversible data hiding scheme. Although common histogram-based reversible data hiding schemes can achieve high image quality, embedding capacity is restricted because general images usually do not contain a great number of pixels with the same pixel values. To improve embedding capacity and retain low distortion, the proposed scheme uses prediction-error values, which are derived from the difference between an original image and a predictive image, instead of using the original pixels to convey a secret message. In the proposed scheme, a predictive image is generated using the mean interpolation prediction method. Since the obtained predictive image is very similar to the original image, prediction-error values are to be tended to zero. That is, a great quantity of peak points gathers around zero. The proposed scheme takes full advantage of this property to increase embedding capacity and retain slight distortion. Moreover, a threshold is used to balance the tradeoff between embedding capacity and image quality, i.e. embedding capacity in the proposed scheme is scalable. Furthermore, only a threshold is needed to record, not a large amount of information of peak and zero points, when high embedding capacity is required. Additionally, a multilevel mechanism is employed to further increase embedding capacity. Experimental results indicate that the proposed scheme is superior to other reversible schemes in terms of both image quality and embedding capacity.

关键词： reversible data hiding lossless data hiding predictive coding histogram modification

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Acquisition of nonlinear forward optics in generative models: Two-stage "downside-up" learning for occluded vision

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NEURAL NETWORKS 2011年第2期24卷 148-158页

作者： Tajima, Satohiro Watanabe, Masataka NHK Japan Broadcasting Corp Nagano Stn Nagano 3808502 Japan Univ Tokyo Grad Sch Frontier Sci Kashiwa Chiba 2778561 Japan Univ Tokyo Fac Engn Bunkyo Ku Tokyo 1130033 Japan

We propose a two-stage learning method which implements occluded visual scene analysis into a generative model, a type of hierarchical neural network with bi-directional synaptic connections. Here, top-down connections simulate forward optics to generate predictions for sensory driven low-level representation, whereas bottom-up connections function to send the prediction error, the difference between the sensory based and the predicted low-level representation, to higher areas. The prediction error is then used to update the high-level representation to obtain better agreement with the visual scene. Although the actual forward optics is highly nonlinear and the accuracy of simulated forward optics is crucial for these types of models, the majority of previous studies have only investigated linear and simplified cases of forward optics. Here we take occluded vision as an example of nonlinear forward optics, where an object in front completely masks out the object behind. We propose a two-staged learning method inspired by the staged development of infant visual capacity. In the primary learning stage, a minimal set of object basis is acquired within a linear generative model using the conventional unsupervised learning scheme. In the secondary learning stage, an auxiliary multi-layer neural network is trained to acquire nonlinear forward optics by supervised learning. The important point is that the high-level representation of the linear generative model serves as the input and the sensory driven low-level representation provides the desired output. Numerical simulations show that occluded visual scene analysis can indeed be implemented by the proposed method. Furthermore, considering the format of input to the multi-layer network and analysis of hidden-layer units leads to the prediction that whole object representation of partially occluded objects, together with complex intermediate representation as a consequence of nonlinear transformation from non-occluded to

关键词： Vision Generative model predictive coding Neural network Occlusion Learning Developmental stage

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Improved prediction methods for scalable predictive animated mesh compression

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JOURNAL OF VISUAL COMMUNICATION AND IMAGE REPRESENTATION 2011年第7期22卷 577-589页

作者： Bici, M. Oguz Akar, Gozde B. Middle E Tech Univ TR-06531 Ankara Turkey

Animated meshes represented as sequences of static meshes sharing the same connectivity require efficient compression. Among the compression techniques, layered predictive coding methods efficiently encode the animated meshes in a structured way such that the successive reconstruction with an adaptable quality can be performed. The decoding quality heavily depends on how well the prediction is performed in the encoder. Due to this fact, in this paper, three novel prediction structures are proposed and integrated into a state of the art layered predictive coder. The proposed structures are based on weighted spatial prediction with its weighted refinement and angular relations of triangles between current and previous frames. The experimental results show that compared to the state of the art scalable predictive coder, up to 30% bitrate reductions can be achieved with the combination of proposed prediction schemes depending on the content and quantization level. (C) 2011 Elsevier Inc. All rights reserved.

关键词： Compression Animated meshes 3D dynamic meshes Time consistent mesh sequence predictive coding Weighted prediction Animated mesh coding Angle based prediction

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Low-Delay Prediction- and Transform-Based Wyner-Ziv coding

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2011年第2期59卷 653-666页

作者： Chen, Xuechen Tuncel, Ertem Univ Calif Riverside Dept Elect Engn Riverside CA 92521 USA

This paper studies low-delay Wyner-Ziv coding, i.e., lossy source coding with side information at the decoder, with emphasis on the extreme of zero delay. To achieve zero delay, a scalar quantizer is followed by scalar coding of quantization indices. In the fixed-length coding scenario, under high-resolution assumptions and appropriately defined decodability constraints, the optimal quantization level density is conjectured to be periodic. This conjecture, which is provable when the correlation is high, allows for a precise analysis of the rate-distortion tradeoff. The performance of variable-length coding with periodic quantization is also characterized. The results are then incorporated in predictive Wyner-Ziv coding for Gaussian sources with memory, and optimal prediction filters are numerically designed so as to strike a balance between maximally exploiting both temporal and spatial correlation and limiting the propagation of distortion due to occasional decoding errors. Finally, the zero-delay schemes are also employed in transform coding with small block lengths, where the Gaussian source and side information are transformed separately with the premise that corresponding transform coefficient pairs exhibit good spatial correlation and minimal temporal correlation. For the specific source-side information pairs studied, it is shown that transform coding, even with a small block-length, outperforms predictive coding. Performances of both predictive and transform coding are also compared with the asymptotic rate-distortion bounds.

关键词： High-resolution quantization low-delay predictive coding transform coding Wyner-Ziv coding

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Simulation during observation of human actions - Theories, empirical studies, applications

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VISION RESEARCH 2011年第8期51卷 827-835页

作者： Zentgraf, Karen Munzert, Joern Bischoff, Matthias Newman-Norlund, Roger D. Univ Bern Inst Sports Sci CH-3012 Bern Switzerland Univ Giessen Bender Inst Neuroimaging D-35394 Giessen Germany Univ Giessen Inst Sports Sci D-35394 Giessen Germany Univ S Carolina Dept Exercise Sci Columbia SC 29208 USA

Historically, data from brain imaging and brain stimulation studies have supported the idea that the processing of observed actions recruits - among other areas - a distinct sub-set of brain sites in the sensory and motor cortices. These empirical findings have initially been linked with the thesis of direct matching as a mechanism of action understanding, i.e., the idea of motor resonance implemented by mirror neurons. In more recent approaches, it has been proposed that the mirror neuron system plays a role in minimizing prediction error when inferring the most likely cause of an observed action. According to these theories, motor resonance is thought to function as predictive coding. Other theoretical accounts suggest that action understanding might result from a hypothesis testing mechanism in which potential goals are continually fed into the system until the correct one is identified. In this review, we will explore the relationship of these theories to specific empirical findings. Finally, we will discuss the implications of these theoretical structures on action observation-based approaches to the optimization of skilled performance in athletes and patients. (C) 2011 Elsevier Ltd. All rights reserved.

关键词： Action observation Mirror neurons Direct matching predictive coding Action reconstruction

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A single functional model accounts for the distinct properties of suppression in cortical area V1

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VISION RESEARCH 2011年第6期51卷 563-576页

作者： Spratling, M. W. Kings Coll London Div Engn London WC2R 2LS England Kings Coll London Dept Informat London WC2R 2LS England

Cross-orientation suppression and surround suppression have been extensively studied in primary visual cortex (V1). These two forms of suppression have some distinct properties which has led to the suggestion that they are generated by different underlying mechanisms. Furthermore, it has been suggested that mechanisms other than intracortical inhibition may be central to both forms of suppression. A simple computational model (PC/BC), in which intracortical inhibition is fundamental, is shown to simulate the distinct properties of cross-orientation and surround suppression. The same model has previously been shown to account for a large range of V1 response properties including orientation-tuning, spatial and temporal frequency tuning, facilitation and inhibition by flankers and textured surrounds as well as a range of other experimental results on cross-orientation suppression and surround suppression. The current results thus provide additional support for the PC/BC model of V1 and for the proposal that the diverse range of response properties observed in V1 neurons have a single computational explanation. Furthermore, these results demonstrate that current neurophysiological evidence is insufficient to discount intracortical inhibition as a central mechanism underlying both forms of suppression. (C) 2011 Elsevier Ltd. All rights reserved.

关键词： Cross-orientation suppression Surround suppression Receptive field Primary visual cortex predictive coding

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The power of imagination - How anticipatory mental imagery alters perceptual processing of fearful facial expressions

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NEUROIMAGE 2011年第2期54卷 1703-1714页

作者： Diekhof, Esther K. Kipshagen, Hanne E. Falkai, Peter Dechent, Peter Baudewig, Juergen Gruber, Oliver Univ Gottingen Dept Psychiat Ctr Translat Res Syst Neurosci & Psychiat D-37075 Gottingen Germany Univ Gottingen Univ Med Ctr Goettingen MR Res Neurol & Psychiat D-37075 Gottingen Germany Free Univ Berlin D-1000 Berlin Germany

Expectancies strongly shape our perception of the world and preconceptions about stimulus characteristics can even bias the sensory system for illusory percepts. Here we assessed with functional magnetic resonance imaging how anticipatory mental imagery of a mildly fearful face created a predictive bias that proactively altered perception of highly fearful faces and generated the "illusion" of reduced fearfulness. We found that anticipatory activation of the fusiform gyrus (FG) was modulated by the fearfulness of the imagined face. Further during anticipatory imagery, regulatory influences from the lateral and ventromedial prefrontal cortex on the FG primed the perceptual system for a subsequent misperception. This was achieved by increasing perceptual activation in higher-order brain regions for the evaluation of affective valence and contextual framing, while at the same time restricting bottom-up arousal and attention to fearful expressions. Anticipatory mental imagery may thus represent an effective antecedent strategy through which emotional perception can be significantly altered. (C) 2010 Elsevier Inc. All rights reserved.

关键词： fMRI predictive coding Misperception Mental simulation Emotion regulation Fusiform face area

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