Yang Wang

Mutual information-based method for selecting informative feature sets

Feature selection is one of the fundamental problems in pattern recognition and data mining. A popular and effective approach to feature selection is based on information theory, namely the mutual information of features and class variable. In this paper we compare eight different mutual information-based feature selection methods. Based on the analysis of the comparison results, we propose a new mutual information-based feature selection method. By taking into account both the class-dependent and class-independent correlation among features, the proposed method selects a less redundant and more informative set of features. The advantage of the proposed method over other methods is demonstrated by the results of experiments on UCI datasets (Asuncion and Newman, 2010 [1]) and object recognition.

Finding shareable informative patterns and optimal coding matrix for multiclass boosting

A multiclass classification problem can be reduced to a collection of binary problems using an error-correcting coding matrix that specifies the binary partitions of the classes. The final classifier is an ensemble of base classifiers learned on binary problems and its performance is affected by two major factors: the qualities of the base classifiers and the coding matrix. Previous studies either focus on one of these factors or consider two factors separately. In this paper, we propose a new multiclass boosting algorithm called AdaBoost.SIP that considers both two factors simultaneously. In this algorithm, informative patterns, which are shareable by different classes rather than only discriminative on specific single class, are generated at first. Then the binary partition preferred by each pattern is found by performing stage-wise functional gradient descent on a margin-based cost function. Finally, base classifiers and coding matrix are optimized simultaneously by maximizing the negative gradient of such cost function. The proposed algorithm is applied to scene and event recognition and experimental results show its effectiveness in multiclass classification.

A weakly supervised approach for object detection based on Soft-Label Boosting

Object detection is an important and challenging problem in the field of computer vision. Classical object detection approaches such as background subtraction and saliency detection do not require manual collection of training samples, but can be easily affected by noise factors, such as luminance changes and cluttered background. On the other hand, supervised learning based approaches such as Boosting and SVM usually have robust performance, but require substantial human effort to collect and label training samples. This study aims to combine the comparative advantages of both kinds of approaches, and its contributions are two-fold: (i) a weakly supervised approach for object detection, which does not require manual collection and labelling of training samples; (ii) an extension of Boosting algorithm denoted as Soft-Label Boosting, which is able to employ training samples with soft (probabilistic) labels instead of hard (binary) labels. Experimental results show that the proposed weakly supervised approach outperforms the state-of-the-art, and even achieves comparable performance to supervised approaches.

Vehicle detection and tracking with low-angle cameras

In this paper, we address the problem of vehicle detection and tracking with low-angle cameras by combining windshield detection and feature points clustering, effectively fusing several primitive image features such as color, edge and interest point. By exploring various heterogenous features and multiple vehicle models, we achieve at least two improvements over the existing methods: higher detection accuracy and the ability to distinguish different vehicle types. Our experiments on real-world traffic video sequences demonstrate the benefits of feature fusion and the improved performance.

Feature clustering for vehicle detection and tracking in road traffic surveillance

In this paper, we formulate the feature clustering problem for vehicle detection and tracking as a general MAP problem and solve it using MCMC. The proposed approach exhibits two advantages over existing methods: general Bayesian model can handle arbitrary objective functions and MCMC guarantees global optimal solution. Our algorithm is validated on real-world traffic video sequences, and is shown to outperform the state-of-the-art approach.

Batch mode active learning for multi-label image classification with informative label correlation mining

The performances of supervised learning techniques on image classification problems heavily rely on the quality of their training images. But the acquisition of high quality training images requires significant efforts from human annotators. In this paper, we propose a novel multi-label batch model active learning (MLBAL) approach that allows the learning algorithm to actively select a batch of informative example-label pairs from which it learns at each learning iteration, so as to learn accurate classifiers with less annotation efforts. Unlike existing methods, the proposed approach fines the active selection granularity from example to example-label pair, and takes into account the informative label correlations for active learning. And the empirical studies demonstrate its effectiveness.

Incremental EM for Probabilistic Latent Semantic Analysis on Human Action Recognition

Human action recognition is a significant task in automatic understanding systems for video surveillance. Probabilistic Latent Semantic Analysis (PLSA) model has been used to learn and recognize human actions in videos. Specifically, PLSA employs the expectation maximization (EM) algorithm for parameter estimation during the training. The EM algorithm is an iterative estimation scheme that is guaranteed to find a local maximum of the likelihood function. However its convergence usually takes a large number of iterations. For action recognition with large amount of training data, this would result in long training time. This paper presents an incremental version of EM to speed up the training of PLSA without sacrificing performance accuracy. The proposed algorithm is tested on two challenging human action datasets. Experimental results demonstrate that the proposed algorithm converges with fewer number of full passes compared with the batch EM algorithm. And the trained PLSA models achieve comparable or better recognition accuracies than those using batch EM training.

A practical approach to multiple super-resolution sprite generation

The MPEG-4 video coding standard introduces a novel concept of sprite or mosaic that is a large image composed of pixels belonging to a video object visible throughout a video segment. The sprite captures spatio-temporal information in a very compact way and makes it possible for efficient object-based video compression. In this paper, we propose a practical approach to generating multiple super-resolution sprites for sprite coding. In order to construct super-resolution sprites and reduce coding cost, we firstly partition a video sequence into multiple independent sprites and group the images covering a similar scene into the same sprite. We then propose efficient and practical algorithms for cumulative global motion estimation and super-resolution sprite construction. Experiments with real video sequences show that the proposed approach outperforms the previous single sprite and multiple sprite techniques.

Saliency detection based on proto-objects and topic model

This paper proposes a novel computational framework for saliency detection, which integrates the saliency map computation and proto-objects detection. The proto-objects are detected based on the saliency map using latent topic model. The detected proto-objects are then utilized to improve the saliency map computation. Extensive experiments are performed on two publicly available datasets. The experimental results show that the proposed framework outperforms the state-of-art methods.

Multi-class Graph Boosting with Subgraph Sharing for Object Recognition

In this paper, we propose a novel multi-class graph boosting algorithm to recognize different visual objects. The proposed method treats subgraph as feature to construct base classifier, and utilizes popular error correcting output code scheme to solve multi-class problem. Both factors, base classifier and error-correcting coding matrix are considered simultaneously. And subgragphs, which are shareable by different classes, are wisely used to improve the classification performance. The experimental results on multi-class object recognition show the effectiveness of the proposed algorithm.