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2012

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Articles 331 - 360 of 12196

Full-Text Articles in Physical Sciences and Mathematics

A Maximum Likelihood Watermark Decoding Scheme, Wenming Lu, Wanqing Li, Rei Safavi-Naini, Philip Ogunbona Dec 2012

A Maximum Likelihood Watermark Decoding Scheme, Wenming Lu, Wanqing Li, Rei Safavi-Naini, Philip Ogunbona

Associate Professor Wanqing Li

Based on the observation that an attack applied on a watermarked image, from a decoding point of view, modifies the distribution of the detection values away from the ideal distribution (without attack) for corresponding watermarking scheme, we propose a generic maximum likelihood decoding scheme by approximating the distribution with a finite Gaussian mixture model. The parameters of the model are estimated using expectation-maximization algorithm. The scheme allows the decoding to be automatically adapted to attacks that the watermarked images have undergone and, in consequence, to improve the decoding accuracy. Experiments on a QIM based watermarking system have clearly verified the …

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A New Divide And Conquer Algorithm For Graph-Based Image And Video Segmentation, Wanqing Li, M. Shi, P. Ogunbona Dec 2012

A New Divide And Conquer Algorithm For Graph-Based Image And Video Segmentation, Wanqing Li, M. Shi, P. Ogunbona

Associate Professor Wanqing Li

The concept of the Shortest (or Minimum) Spanning Tree (SST)and Recursive SST (RSST) of an undirected weighted graph has been successfully applied in image segmentation and edge detection. This paper presents a divide-and-conquer approach for (R)SST based image segmentation in order to over-come the problem of high computational complexity associated with conventional graph algorithms. In the simplest form, the proposed approach, block-based RSST (BRSST), first divides the image into rectangular blocks, finds the (R)SST of each block individually using conventional graph algorithms and, then, merges the (R) SSTs of all image blocks to form an (R)SST of the entire image. …

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Illumination Invariant Face Detection Using Classifier Fusion, Alister Cordiner, Philip Ogunbona, Wanqing Li Dec 2012

Illumination Invariant Face Detection Using Classifier Fusion, Alister Cordiner, Philip Ogunbona, Wanqing Li

Associate Professor Wanqing Li

An approach to the problem of illumination variations in face detection that uses classifier fusion is presented. Multiple face detectors are seperately trained for different illumination environments and their results are combined using a combination rule. To define the illumination environments, the training samples are clustered based on their illumination using unsupervised training. Different methods of clustering the samples and combining the outputs of the classifiers are examined. Experiments with the AR face database show that the proposed method achieves higher accuracy than the traditional monolithic face detection method.

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Optimal Image Watermark Decoding, Wenming Lu, Wanqing Li, Reihaneh Safavi-Naini, Philip Ogunbona Dec 2012

Optimal Image Watermark Decoding, Wenming Lu, Wanqing Li, Reihaneh Safavi-Naini, Philip Ogunbona

Associate Professor Wanqing Li

Not much has been done in utilizing the available information at the decoder to optimize the decoding performance of watermarking systems. This paper focuses on analyzing different decoding methods, namely, Minimum Distance, Maximum Likelihood and Maximum a-posteriori decoding given varying information at the decoder in the blind detection context. Specifically, we propose to employ Markov random fields to model the prior information given the embedded message is a structured logo. The application of these decoding methods in Quantization Index Modulation systems shows that the decoding performance can be improved by Maximum Likelihood decoding that exploits the property of the attack …

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Age Estimation Based On Extended Non-Negative Matrix Factorization, Ce Zhan, Wanqing Li, Philip Ogunbona Dec 2012

Age Estimation Based On Extended Non-Negative Matrix Factorization, Ce Zhan, Wanqing Li, Philip Ogunbona

Associate Professor Wanqing Li

Previous studies suggested that local appearance-based methods are more efficient than geometric-based and holistic methods for age estimation. This is mainly due to the fact that age information are usually encoded by the local features such as wrinkles and skin texture on the forehead or at the eye corners. However, the variations of theses features caused by other factors such as identity, expression, pose and lighting may be larger than that caused by aging. Thus, one of the key challenges of age estimation lies in constructing a feature space that could successfully recovers age information while ignoring other sources of …

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A Novel Video-Based Smoke Detection Method Using Image Separation, Hongda Tian, Wanqing Li, Lei Wang, Philip Ogunbona Dec 2012

A Novel Video-Based Smoke Detection Method Using Image Separation, Hongda Tian, Wanqing Li, Lei Wang, Philip Ogunbona

Associate Professor Wanqing Li

In the state-of-the-art video-based smoke detection methods, the representation of smoke mainly depends on the visual information in the current image frame. In the case of light smoke, the original background can be still seen and may deteriorate the characterization of smoke. The core idea of this paper is to demonstrate the superiority of using smoke component for smoke detection. In order to obtain smoke component, a blended image model is constructed, which basically is a linear combination of background and smoke components. Smoke opacity which represents a weighting of the smoke component is also defined. Based on this model, …

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Image Reconstruction From Sparse Projections Using S-Transform, Jianhua Luo, Jiahai Liu, Wanqing Li, Yuemin Zhu, Ruiyao Jiang Dec 2012

Image Reconstruction From Sparse Projections Using S-Transform, Jianhua Luo, Jiahai Liu, Wanqing Li, Yuemin Zhu, Ruiyao Jiang

Associate Professor Wanqing Li

Sparse projections are an effective way to reduce the exposure to radiation during X-ray CT imaging. However, reconstruction of images from sparse projection data is challenging. This paper introduces a new sparse transform, referred to as S-transform, and proposes an accurate image reconstruction method based on the transform. The S-transform effectively converts the ill-posed reconstruction problem into a well-defined one by representing the image using a small set of transform coefficients. An algorithm is proposed that efficiently estimates the S-transform coefficients from the sparse projections, thus allowing the image to be accurately reconstructed using the inverse S-transform. The experimental results …

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Ranking Social Emotions By Learning Listwise Preference, Qishen Wang, Ou Wu, Weiming Hu, Jinfeng Yang, Wanqing Li Dec 2012

Ranking Social Emotions By Learning Listwise Preference, Qishen Wang, Ou Wu, Weiming Hu, Jinfeng Yang, Wanqing Li

Associate Professor Wanqing Li

Abstract-Emotion modeling has received a great attention in recent years. This paper models the online social emotions that are the online users' emotional responds when they are exposed to news articles. Specifically, we rank social emotion labels for online documents. Unlike the existing method, referred to as Pair-LR, which learns pairwise preference and adopts binary classification, we address the problem of ranking social emotions by learning listwise preference. In particular, a novel approach, referred to as List-LR, is proposed to learn a ranking model for social emotion labels of online documents by minimizing the listwise loss defined on instances. Empirical …

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Stereoscopic Panoramic Video Generation Using Centro-Circular Projection Technique, Chaminda Weerasinghe, Wanqing Li, Philip Ogunbona Dec 2012

Stereoscopic Panoramic Video Generation Using Centro-Circular Projection Technique, Chaminda Weerasinghe, Wanqing Li, Philip Ogunbona

Associate Professor Wanqing Li

This paper presents a method of stereoscopic panoramic video generation including techniques for panorama projection, stitching and calibration for various depth planes. The methods described can be used on video sequences captured by an arrangement of multiple pairs of cameras or multiple stereoscopic cameras mounted on a regular polygonal shaped camera rig. Algorithms can also be used in combination or separately, for generating both stereoscopic and monoscopic video and still panoramas.

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On The Combination Of Local Texture And Global Structure For Food Classification, Zhimin Zong, Duc Thanh Nguyen, Philip O. Ogunbona, Wanqing Li Dec 2012

On The Combination Of Local Texture And Global Structure For Food Classification, Zhimin Zong, Duc Thanh Nguyen, Philip O. Ogunbona, Wanqing Li

Associate Professor Wanqing Li

This paper proposes a food image classification method using local textural patterns and their global structure to describe the food image. In this paper, a visual codebook of local textural patterns is created by employing Scale Invariant Feature Transformation (SIFT) interest point detector with the Local Binary Pattern (LBP) feature. In addition to describing the food image using local texture, the global structure of the food object is represented as the spatial distribution of the local textural structures and encoded using shape context. We evaluated the proposed method on the Pittsburgh Fast-Food Image (PFI) dataset. Experimental results showed that the …

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Facial Expression Recognition For Multiplayer Online Games, Ce Zhan, Wanqing Li, Philip O. Ogunbona, Farzad Safaei Dec 2012

Facial Expression Recognition For Multiplayer Online Games, Ce Zhan, Wanqing Li, Philip O. Ogunbona, Farzad Safaei

Associate Professor Wanqing Li

The Multiplayer Online Game (MOG) becomes more popular than any other types of computer games for its collaboration, communication and interaction ability. However, compared with the ordinary human communication, the MOG still has many limitations, especially in communication using facial expressions. Although detailed facial animation has already been achieved in a number of MOGs, players have to use text commands to control avatars expressions. In this paper, we briefly review the state of the art in facial expression recognition and propose an automatic expression recognition system that can be integrated into a MOG to control the avatar’s facial expressions. We …

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Local Representation Of Faces Through Extended Nmf, Ce Zhan, Wanqing Li, Philip Ogunbona Dec 2012

Local Representation Of Faces Through Extended Nmf, Ce Zhan, Wanqing Li, Philip Ogunbona

Associate Professor Wanqing Li

"Presented is an extension of the non-negative matrix factorisation (NMF) by imposing an orthogonality constraint on the basis matrix and controlling the sparseness of the coefficient matrix for robust learning of compact local part-based representation of face images. The extended NMF is solved by a projected gradient algorithm with a data-driven initialisation scheme. In addition, an indicator is proposed to objectively measure the locality and compactness of local part-based representation and to quantitatively evaluate the efficiency of the extended NMF. Experimental results on benchmark face databases show that the proposed extended NMF is much more effective in learning local part-based …

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Novel Architecture For Surveillance Cameras With Complementary Metal Oxide Semiconductor Image Sensors, Igor Kharitonenko, Wanqing Li, Chaminda Weerasinghe Dec 2012

Novel Architecture For Surveillance Cameras With Complementary Metal Oxide Semiconductor Image Sensors, Igor Kharitonenko, Wanqing Li, Chaminda Weerasinghe

Associate Professor Wanqing Li

This work presents a novel architecture of an intelligent video surveillance camera. It is embedded with automated scene analysis and object behavior detection, so that operators can monitor more venues relying on the system that provides immediate response to suspicious events. The developed camera turns passive video data recording systems into active collaborators with security operators leaving to them only high-level decision making, while automatically carrying out all monotonous work on continuous video monitoring. When there is no alarming activity inside a restricted area the camera automatically turns back to the whole view mode.

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Simulation Of Human Motion For Learning And Recognition, Gang Zheng, Wanqing Li, Philip Ogunbona, Liju Dong, Igor Kharitonenko Dec 2012

Simulation Of Human Motion For Learning And Recognition, Gang Zheng, Wanqing Li, Philip Ogunbona, Liju Dong, Igor Kharitonenko

Associate Professor Wanqing Li

Acquisition of good quality training samples is becoming a major issue in machine learning based human motion analysis. This paper presents a method to simulate human body motion with the intention to establish a human motion corpus for learning and recognition. The simulation is achieved by a unique temporal-spatial-temporal decomposition of human body motion into actions, joint actions and actionlets based on the human kinematic model. The actionlet models the primitive moving phase of a joint and can be simulated based on the kinesiological study. A joint action is formed by proper concatenation of actionlets and an action is a …

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A Semi-Supervised Map Segmentation Of Brain Tissues, Wanqing Li, C. Desilver, Y. Attikiouzel Dec 2012

A Semi-Supervised Map Segmentation Of Brain Tissues, Wanqing Li, C. Desilver, Y. Attikiouzel

Associate Professor Wanqing Li

This paper presents a method for semi-supervised MAP (maximum a-posterior probability) segmentation of brain tissues where labelled data are available for either all types of tissues or only a few types of tissues possibly at different levels of quality. The proposed MAP segmentation takes supervised and unsupervised segmentation as its two special cases where, respectively, quality labelled data is available or there is no labelled data at all. Experiments on real MR images have shown that the proposed method improved the segmentation accuracy substantially with only a few labelled data in comparison with both fully supervised method with the same …

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Human Detection Using Local Shape And Non-Redundant Binary Patterns, Duc Thanh Nguyen, Wanqing Li, Philip Ogunbona Dec 2012

Human Detection Using Local Shape And Non-Redundant Binary Patterns, Duc Thanh Nguyen, Wanqing Li, Philip Ogunbona

Associate Professor Wanqing Li

Motivated by the advantages of using shape matching technique in detecting objects in various postures and viewpoints and the discriminative power of local patterns in object recognition, this paper proposes a human detection method combining both shape and appearance cues. In particular, local shapes of the body parts are detected using template matching. Based on body parts' shapes, local appearance features are extracted. We introduce a novel local binary pattern (LBP) descriptor, called Non-Redundant LBP (NRLBP), to encode local appearance of human. The proposed method was evaluated and compared with other state-of-the-art human detection methods on two commonly used datasets: …

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Research Of Unsupervised Posture Modeling And Action Recognition Based On Spatial-Temporal Interesting Points, Chuan-Xu Wang, Yun Liu, Wanqing Li Dec 2012

Research Of Unsupervised Posture Modeling And Action Recognition Based On Spatial-Temporal Interesting Points, Chuan-Xu Wang, Yun Liu, Wanqing Li

Associate Professor Wanqing Li

Posture modeling is critical for action description and recognition,a posture modeling and action recognition method is proposed in this paper.Spatial Temporal Interesting Points (STIPs) are extracted from learning samples,in fact,one posture consists of a set of STIPs;a unsupervised clustering method is adopted to classify salient postures from these posture samples,then a GMM model is established for each clustering result;transitional probability among salient postures are calculated,and a Visible state Markov Model(VMM) is learnt to describe various actions.Bi-gram method is put forward for action recognition,Extensive experiments are conducted and the results prove its robustness and validity.

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Description Of Evolutional Changes In Image Time Sequences Using Mpeg-7 Visual Descriptors, Lei Ye, Lingzhi Cao, Philip Ogunbona, Wanqing Li Dec 2012

Description Of Evolutional Changes In Image Time Sequences Using Mpeg-7 Visual Descriptors, Lei Ye, Lingzhi Cao, Philip Ogunbona, Wanqing Li

Associate Professor Wanqing Li

Colour and texture visual descriptors have been developed to represent structural features of images, mainly under the Query-by- Example (QBE) image retrieval paradigm. This paper explores applicability of MPEG-7 visual descriptors to describe and measure evolutional changes in image time sequences, using a fruit rotting process as an example. The research found that MPEG-7 visual descriptors can be applied to describe evolutional changes in image time sequences. The experimental results are provided using bananas captured in image time sequences. The results show the desirable monotonicity of description metrics of MPEG-7 similarity matching for image time sequences and their sensitivity to …

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An Improved Template Matching Method For Object Detection, Duc Thanh Nguyen, Wanqing Li, Philip Ogunbona Dec 2012

An Improved Template Matching Method For Object Detection, Duc Thanh Nguyen, Wanqing Li, Philip Ogunbona

Associate Professor Wanqing Li

This paper presents an improved template matching method that combines both spatial and orientation information in a simple and effective way. The spatial information is obtained through a generalized distance transform (GDT) that weights the distance transform more on the strong edge pixels and the orientation information is represented as an orientation map (OM) which is calculated from local gradient. We applied the proposed method to detect humans, cars, and maple leaves from images. The experimental results have shown that the proposed method outperforms the existing template matching methods and is robust against cluttered background.

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Face Recognition From Single Sample Based On Human Face Perception, Ce Zhan, Wanqing Li, Philip Ogunbona Dec 2012

Face Recognition From Single Sample Based On Human Face Perception, Ce Zhan, Wanqing Li, Philip Ogunbona

Associate Professor Wanqing Li

Although research show that human recognition performance for unfamiliar faces is relatively poor, when the sample is always available for analysis and becomes ”familiar”, people are able to recognize a previous unknown face from single sample. In this paper, a method is proposed to deal with the one sample per person face recognition problem based on the process how unfamiliar faces become familiar to people. Particularly, quantized local features which learnt from generic face dataset are used in the proposed method to mimic the prototype effect of human face recognition. Furthermore, a landmark-based scheme is introduced to quantify the distinctiveness …

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2d To Pseudo-3d Conversion Of "Head And Shoulder" Images Using Feature Based Parametric Disparity Maps, Chaminda Weerasinghe, Philip Ogunbona, Wanqing Li Dec 2012

2d To Pseudo-3d Conversion Of "Head And Shoulder" Images Using Feature Based Parametric Disparity Maps, Chaminda Weerasinghe, Philip Ogunbona, Wanqing Li

Associate Professor Wanqing Li

This paper presents a method of converting a 2D still photo containing the head & shoulders of a human (e.g. a passport photo) to pseudo-3D, so that the depth can be perceived via stereopsis. This technology has the potential to be included in self-serve photo booths and, also as an added accessory (i.e. software package) for digital still cameras and scanners. The basis of the algorithm is to exploit the ability of the human visual system in combining monoscopic and stereoscopic cues for depth perception. Common facial features are extracted from the 2D photograph, in order to create a parametric …

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Simultaneous Map Estimation Of Inhomogeneity And Segmentation Of Brain Tissues From Mr Images, Wanqing Li, C. Desilver, Y. Attikiouzel Dec 2012

Simultaneous Map Estimation Of Inhomogeneity And Segmentation Of Brain Tissues From Mr Images, Wanqing Li, C. Desilver, Y. Attikiouzel

Associate Professor Wanqing Li

Intrascan and interscan intensity inhomogeneities have been identified as a common source of making many advanced segmentation techniques fail to produce satisfactory results in separating brains tissues from multi-spectral magnetic resonance (MR) images. A common solution is to correct the inhomogeneity before applying the segmentation techniques. This paper presents a method that is able to achieve simultaneous semi-supervised MAP (maximum a-posterior probability) estimation of the inhomogeneity field and segmentation of brain tissues, where the inhomogeneity is parameterized. Our method can incorporate any available incomplete training data and their contribution can be controlled in a flexible manner and therefore the segmentation …

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Regression Analysis Under Probabilistic Multi-Linkage, Gunky Kim, Raymond Chambers Dec 2012

Regression Analysis Under Probabilistic Multi-Linkage, Gunky Kim, Raymond Chambers

Dr Gunky Kim

"Linkage errors can occur when probability-based methods are used to link records from two distinct data sets corresponding to the same target population. Current approaches to modifying standard methods of regression analysis to allow for these errors only deal with the case of two linked data sets and assume that the linkage process is complete, that is, all records on the two data sets are linked. This study extends these ideas to accommodate the situation when more than two data sets are probabilistically linked and the linkage is incomplete."

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Method Of Color Interpolation In A Single Sensor Color Camera Using Green Channel Separation, Chaminda Weerasinghe, Igor Kharitonenko, Philip Ogunbona Dec 2012

Method Of Color Interpolation In A Single Sensor Color Camera Using Green Channel Separation, Chaminda Weerasinghe, Igor Kharitonenko, Philip Ogunbona

Dr Igor Kharitonenko

This paper presents a color interpolation algorithm for a single sensor color camera. The proposed algorithm is especially designed to solve the problem of pixel crosstalk among the pixels of different color channels. Interchannel cross-talk gives rise to blocking effects on the interpolated green plane, and also spreading of false colors into detailed structures. The proposed algorithm separates the green channel into two planes, one highly correlated with the red channel and the other with the blue channel. These separate planes are used for red and blue channel interpolation. Experiments conducted on McBeth color chart and natural images have shown …

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Human Motion Simulation And Action Corpus, Gang Zheng, Wanqing Li, Philip Ogunbona, Liju Dong, Igor Kharitonenko Dec 2012

Human Motion Simulation And Action Corpus, Gang Zheng, Wanqing Li, Philip Ogunbona, Liju Dong, Igor Kharitonenko

Dr Igor Kharitonenko

Acquisition of large scale good quality training samples is becoming a major issue in machine learning based human motion analysis. This paper presents a method to simulate continuous gross human body motion with the intention to establish a human motion corpus for learning and recognition. The simulation is achieved by a temporal-spatialtemporal decomposition of human motion into actions, joint actions and actionlets based on the human kinematic model. The actionlet models the primitive moving phase of a joint and represents the muscle movement governed by kinesiological principles. Joint actions and body actions are constructed from actionlets through constrained concatenation and …

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Novel Architecture For Surveillance Cameras With Complementary Metal Oxide Semiconductor Image Sensors, Igor Kharitonenko, Wanqing Li, Chaminda Weerasinghe Dec 2012

Novel Architecture For Surveillance Cameras With Complementary Metal Oxide Semiconductor Image Sensors, Igor Kharitonenko, Wanqing Li, Chaminda Weerasinghe

Dr Igor Kharitonenko

This work presents a novel architecture of an intelligent video surveillance camera. It is embedded with automated scene analysis and object behavior detection, so that operators can monitor more venues relying on the system that provides immediate response to suspicious events. The developed camera turns passive video data recording systems into active collaborators with security operators leaving to them only high-level decision making, while automatically carrying out all monotonous work on continuous video monitoring. When there is no alarming activity inside a restricted area the camera automatically turns back to the whole view mode.

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A Prototype Of Autonomous Intelligent Surveillance Cameras, Wanqing Li, Igor Kharitonenko, S. Lichman, C. Weerasinghe Dec 2012

A Prototype Of Autonomous Intelligent Surveillance Cameras, Wanqing Li, Igor Kharitonenko, S. Lichman, C. Weerasinghe

Dr Igor Kharitonenko

This paper presents an architecture and an FPGAbased prototype of an autonomous intelligent video surveillance camera. The camera takes the advantage of high resolution of CMOS image sensors and enables instantly automatic pan, tilt and zoom adjustment based upon motion activity. It performs automated scene analysis and provides immediate response to suspicious events by optimizing camera capturing parameters. The video output of the camera can be optimized to any region of interest while the camera continues to monitor the entire scene. Field trials of the prototyped camera have verified the proposed architecture.

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Cmos Sensor Cross-Talk Compensation For Digital Cameras, Wanqing Li, Philip Ogunbona, Yu Shi, Igor Kharitonenko Dec 2012

Cmos Sensor Cross-Talk Compensation For Digital Cameras, Wanqing Li, Philip Ogunbona, Yu Shi, Igor Kharitonenko

Dr Igor Kharitonenko

This paper presents two algorithms for removing the cross-talk effect in CMOS sensor based color-imaging systems. The algorithms work on the Bayer raw data and have low computational complexity. Experimental results on Macbeth color chart and real images demonstrated that both algorithms can effectively eliminate the cross-talk effect and produce better quality images with conventional color interpolation and correction algorithms designed for CCD image sensors. Complexity of the algorithms is also analyzed.

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Modelling Of Color Cross-Talk In Cmos Image Sensors, Wanqing Li, Philip Ogunbona, Yan Shi, Igor Kharitonenko Dec 2012

Modelling Of Color Cross-Talk In Cmos Image Sensors, Wanqing Li, Philip Ogunbona, Yan Shi, Igor Kharitonenko

Dr Igor Kharitonenko

This paper presents a way to model the cross-talk effect in CMOS image sensors. Two algorithms are derived from the model; both of them work on the Bayer raw data and have low computational complexity. Experiments on Macbeth color chart and real images have shown the effectiveness of the modeling to eliminate the cross-talk effect and produce better quality images with traditional color interpolation and correction algorithms designed for CCD image sensors.

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Visual Perceptual Process Model And Object Segmentation, Wanqing Li, P. Ogunbona, Lei Ye, Igor Kharitonenko Dec 2012

Visual Perceptual Process Model And Object Segmentation, Wanqing Li, P. Ogunbona, Lei Ye, Igor Kharitonenko

Dr Igor Kharitonenko

Modeling human visual process is crucial for automatic object segmentation that is able to produce consistent results to human perception. Based on the latest understanding of how human performs the task of extracting objects from images, we proposed a graph-based computational framework to model the visual process. The model supports the hierarchical nature of human visual perception and consists of the key steps of human visual perception including pre-attentive (pre-constancy) grouping, figure-and-ground organization, and attentive (post-constancy) grouping. A divide-and-conquer implementation of the model based on the concept of shortest spanning tree (SST) has demonstrated the potential of the model for …

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