Search

We proposed a region based method to recognize human actions from video sequences. Unlike other region based methods, it works with the surrounding regions of the human silhouette termed as negative space. This paper further extends the idea of negative space to cope with the changes in viewpoints. It also addresses the problem of long shadows which is one of the major challenges of human action recognition. Some systems attempt suppressing shadows during the segmentation process but our system takes input of segmented binary images of which the shadow is not suppressed. This makes our system less dependent on segmentation process. Further, this approach can complement the positive space (silhouette) based methods to boost recognition. The system consists of a hierarchical processing: histogram analysis on segmented input image, followed by motion and shape feature extraction, pose sequence analysis by employing Dynamic Time Warping and at last classification by Nearest Neighbor classifier. We evaluated our system by most commonly used datasets and achieved higher accuracy than the state of the arts methods. Our system can also retrieve video sequences from queries of human action sequences.

In this paper, we propose a novel ellipse detection method for real images. The proposed method uses the information of edge curvature and their convexity in relation to other edge contours as clues for identifying edge contours that can be grouped together. A search region is computed for every edge contour that contains other edge contours eligible for grouping with the current edge contour. A two-dimensional Hough transform is performed in an intermediate step, in which we use a new ‘relationship score’ for ranking the edge contours in a group, instead of the conventional histogram count. The score is found to be more selective and thus more efficient. In addition, we use three novel saliency criteria, that are non-heuristic and consider various aspects for quantifying the goodness of the detected elliptic hypotheses and finally selecting good elliptic hypotheses. The thresholds for selection of elliptic hypotheses are determined by the detected hypotheses themselves, such that the selection is free from human intervention. The method requires a few seconds in most cases. So, it is suitable for practical applications. The performance of the proposed ellipse detection method has been tested on a dataset containing 1200 synthetic images and the Caltech 256 dataset containing real images. In both cases, the results show that the proposed ellipse detection method performs far better than existing methods and is close to the ideal results, with precision, recall, and F-measure, all very close to 1. Further, the method is robust to the increase in the complexity of the images (such as overlapping ellipses, occluded ellipses), while the performance of the contemporary methods deteriorates significantly.

The aim of computational learning algorithm is to establish grounds that work for any types of data, once and for all. However, majority of the classifiers have their base from balanced datasets. This paper discusses the issues related to imbalanced data distribution problem and the common strategy to deal with imbalance datasets. We propose a model capable of handling imbalance datasets well in which other typical classifiers fail to do so. The model adopted a derivation of support vector machines in selecting variables so that the problem of imbalanced data distribution can be relaxed. Then, we used an Emergent Self-Organizing Map (ESOM) to cluster the ranker features so as to provide clusters for unsupervised classification. This work progresses by examining the efficiency of the model in evaluating imbalanced datasets. Experimental results show that the criterion based on weight vector derivative achieves good results and performs consistently well over imbalance datasets. In general, our approach outperforms other classification methods which are unable to handle the imbalanced data distribution in the testing datasets.

This paper presents a robust methodology that automatically counts moving vehicles along an expressway. The domain of interest for this paper is using both neuro-fuzzy network and simple image processing techniques to implement traffic flow monitoring and analysis. As this system is dedicated for outdoor applications, efficient and robust processing methods are introduced to handle both day and night analysis. In our study, a neuro-fuzzy network based on the Hebbian-Mamdani rule reduction architecture is used to classify and count the number of vehicles that passed through a three- or four-lanes expressway. As the quality of the video captured is corrupted under noisy outdoor environment, a series of preprocessing is required before the features are fed into the network. A vector of nine feature values is extracted to represent whether a vehicle is passing through a lane and this vector serves as input patterns would be used to train the neuro-fuzzy network. The vehicle counting and classification would then be performed by the well-trained network. The novel approach is benchmarked against the MLP and RBF networks. The results of using our proposed neuro-fuzzy network are very encouraging with a high degree of accuracy.

The problem confronted in the content-based image retrieval research is the semantic gap between the low-level feature representing and high-level semantics in the images. This paper describes a way to bridge such gap: by learning the similar images given from the user, the system extracts the similar region pairs and classifies those similar region pairs either as object or non-object semantics, and either as object-relation or non-object-relation semantics automatically, which are obtained from comparing the distances and spatial relationships in the similar region pairs by themselves. The system also extracts interesting parts of the features from the similar region pair and then adjusts each interesting feature and region pair weight dynamically. Using those objects and object-relation semantics as well as the dynamic weights adjustment from the similar images, the semantics of those similar images can be mined and used for searching the similar images. The experiments show that the proposed system can retrieve the similar images well and efficient.

One of the most popular frameworks for the adaptive processing of data structures to date, was proposed by Frasconi et al. [Frasconi, P., Gori, M., & Sperduti, A. (1998). A general framework for adaptive processing of data structures. IEEE Transactions on Neural Networks, 9(September), 768-785], who used a Backpropagation Through Structures (BPTS) algorithm [Goller, C., & Kuchler, A. (1996). Learning task-dependent distributed representations by back-propagation through structures. In Proceedings of IEEE international conference on neural networks (pp. 347-352); Tsoi, A. C. (1998). Adaptive processing of data structure: An expository overview and comments. Technical report in Faculty Informatics. Wollongong, Australia: University of Wollongong] to carry out supervised learning. This supervised model has been successfully applied to a number of learning tasks that involve complex symbolic structural patterns, such as image semantic structures, internet behavior, and chemical compounds. In this paper, we extend this model, using probabilistic estimates to acquire discriminative information from the learning patterns. Using this probabilistic estimation, smooth discriminant boundaries can be obtained through a process of clustering onto the observed input attributes. This approach enhances the ability of class discrimination techniques to recognize structural patterns. The proposed model is represented by a set of Gaussian Mixture Models (GMMs) at the hidden layer and a set of ''weighted sum input to sigmoid function'' models at the output layer. The proposed model's learning framework is divided into two phases: (a) locally unsupervised learning for estimating the parameters of the GMMs and (b) globally supervised learning for fine-tuning the GMMs' parameters and optimizing weights at the output layer. The unsupervised learning phase is formulated as a maximum likelihood problem that is solved by the expectation-maximization (EM) algorithm. The supervised learning phase is formulated as a cost minimization problem, using the least squares optimization or Levenberg-Marquardt method. The capabilities of the proposed model are evaluated in several simulation platforms. From the results of the simulations, not only does the proposed model outperform the original recursive model in terms of learning performance, but it is also significantly better at classifying and recognizing structural patterns.

In human-computer interaction, there is a need for computer to recognize human facial expression accurately. This paper proposes a novel and effective approach for facial expression recognition that analyzes a sequence of images (displaying one expression) instead of just one image (which captures the snapshot of an emotion). Fourier transform is employed to extract features to represent an expression. The representation is further processed using the fuzzy C means computation to generate a spatio-temporal model for each expression type. Unknown input expressions are matched to the models using the Hausdorff distance to compute dissimilarity values for classification. The proposed technique has been tested with the CMU expression database, generating superior results as compared to other approaches.

An industrial neural network based crowd monitoring system for surveillance at underground station platforms is presented. The developed system was thoroughly off-line tested by video images obtained from the underground station platform at Hong Kong. The developed system enables the density level of crowd to be automatically estimated. Crowd estimation is carried out by extracting a set of significant features from sequence of video images. The extracted features are modelled by a neural network for estimating the level of crowd density. The learning process is based upon an efficient hybrid type global learning algorithms, which are capable of providing good learning performance. Very promising results were obtained in terms of estimation accuracy and real-time response capability to alert the operators automatically.

A hybrid fast training algorithm for feedforward networks is proposed. In this algorithm, the weights connecting the last hidden and output layers are firstly evaluated by the least-squares algorithm, whereas the weights between input and hidden layers are evaluated using the modified gradient descent algorithms. The effectiveness of the proposed algorithm is demonstrated by applying it to the sunspot and Mackey–Glass time-series prediction. The results showed that the proposed algorithm can greatly reduce the number of flops required to train the networks. The proposed algorithm is also applied to crowd estimation at underground stations and very promising results are obtained.

The major limitations of conventional learning algorithms are attributed to local minima and slow convergence speed. This paper presents a novel heuristics approach for neural networks global learning algorithm. The proposed algorithm is based upon the least-squares (LS) method to maintain the fast convergence speed and a Penalty (PEN) approach to solve the problem of local minima. The penalty term superimposes into the error surface, which likely to provide a way of escape from the local minima when the convergence stalls. The choice and adjustment for the penalty factor are also derived to demonstrate the effect of the penalty term and to ensure the convergence of the algorithm. The developed learning algorithm is applied to several problems of classification application. In all the tested problems, the proposed algorithm outperforms other conventional algorithms in terms of convergence speed and the ability of escaping from the local minima.