10042390
Adaptive learning of an accurate skin-color model
Due to variations of lighting conditions, camera hardware settings, and the range of skin coloration among human beings, a pre-defined skin-color model cannot accurately capture the wide distribution of skin colors in individual images. In this paper, we propose an adaptive skin-detection method, which allows modeling true skin-color distribution with significantly higher accuracy and flexibility than other methods attain. In principle, the proposed method follows a two-step process. For a given image, we first perform a rough skin classification using a generic skin model, which defines the skin-similar space. In the second step, a Gaussian mixture model (GMM), specific to the image under consideration and refined from the skin-similar space, is derived using the standard expectation-maximization (EM) algorithm. Then, we use an SVM (support vector machine) classifier to identify the skin Gaussian from the trained GMM (which contains two Gaussian components) by incorporating spatial and shape information of the skin pixels. This adaptive method can be applied to both still images and video applications. Results of extensive experiments performed on live video sequences and large image databases have demonstrated the effectiveness and benefits of the proposed model.
5411538
A unified adaptive approach to accurate skin detection
Due to variations of lighting conditions and camera hardware settings and the existence of many ethnic people with a wide range of skin colors, a generic skin model is often inadequate to accurately capture the skin distribution for individual images. In this paper, we propose an adaptive skin detection framework, which allows modeling title skin distribution with significantly higher accuracy and flexibility. First, an adaptive skin model, specific to the image under consideration and refined from the skin-similar space, is derived using a Gaussian mixture model (GMM) and standard expectation maximization (EM) algorithm. Then, we develop a support vector machine (SVM) classifier to identify the skin Gaussian from the trained GMM (with two Gaussian components) by incorporating spatial and shape information of skin pixels. Extensive experimental results performed on large image databases have demonstrated the effectiveness and benefits of the proposed approach.
7800101
Fast Human Detection Using a Cascade of Histograms of Oriented Gradients
We integrate the cascade-of-rejectors approach with the Histograms of Oriented Gradients (HoG) features to achieve a fast and accurate human detection system. The features used in our system are HoGs of variable-size blocks that capture salient features of humans automatically. Using AdaBoost for feature selection, we identify the appropriate set of blocks, from a large set of possible blocks. In our system, we use the integral image representation and a rejection cascade which significantly speed up the computation. For a 320 × 280 image, the system can process 5 to 30 frames per second depending on the density in which we scan the image, while maintaining an accuracy level similar to existing methods.
13298742
Using visual features for anti-spam filtering
Unsolicited commercial email (UCE), also known as spam, has been a major problem on the Internet. In the past, researchers have addressed this problem as a text classification or categorization problem. However, as spammers' techniques continue to evolve and the genre of email content becomes more and more diverse, text-based anti-spam approaches alone are no longer sufficient. In this paper, we propose a novel anti-spam system which utilizes visual clues, in addition to text information in the email body, to determine whether a message is spam. We analyze a large collection of spam emails containing images and identify a number of useful visual features for this application. We then propose using one-class support vector machines (SVM) as the underlying base classifier for anti-spam filtering. The experimental results demonstrate that the proposed system can add significant filtering power to the existing text-based anti-spam filters.
33192319
Hierarchical model based human motion tracking
Image sequence based tracking is the pivotal technique of human motion. In the paper, we first propose an appropriate human model and color model. Second, two approaches are proposed aiming at two different levels of color-block information including the boundary and the inner-area: the extraction of the boundary algorithm is based on the Robert operator and the clustering algorithm is based on self-adaptation. Third, we unite two regions, which are processed by different approaches. This step counteracts the ambiguity of obtaining information from each level. Finally, after the rough area of the color-block is obtained, the boundary of the color-block is determined by calculating the histogram of the X,Y coordinate of every point on the boundary of the block. Experimental results are presented.
8242374
Evolutionary techniques for updating query cost models in a dynamic multidatabase environment
Abstract.Deriving local cost models for query optimization in a dynamic multidatabase system (MDBS) is a challenging issue. In this paper, we study how to evolve a query cost model to capture a slowly-changing dynamic MDBS environment so that the cost model is kept up-to-date all the time. Two novel evolutionary techniques, i.e., the shifting method and the block-moving method, are proposed. The former updates a cost model by taking up-to-date information from a new sample query into consideration at each step, while the latter considers a block (batch) of new sample queries at each step. The relevant issues, including derivation of recurrence updating formulas, development of efficient algorithms, analysis and comparison of complexities, and design of an integrated scheme to apply the two methods adaptively, are studied. Our theoretical and experimental results demonstrate that the proposed techniques are quite promising in maintaining accurate cost models efficiently for a slowly changing dynamic MDBS environment. Besides the application to MDBSs, the proposed techniques can also be applied to the automatic maintenance of cost models in self-managing database systems.
2629654
Period Optimization for Hard Real-time Distributed Automotive Systems
The complexity and physical distribution of modern active-safety automotive applications requires the use of distributed architectures. These architectures consist of multiple electronic control units (ECUs) connected with standardized buses. The most common configuration features periodic activation of tasks and messages coupled with run-time priority-based scheduling. The correct deployment of applications on such architectures requires end-to- end latency deadlines to be met. This is challenging since deadlines must be enforced across a set of ECUs and buses, each of which supports multiple functionality. The need for accommodating legacy tasks and messages further complicates the scenario. In this work, we automatically assign task and message periods for distributed automotive systems. This is accomplished by leveraging schedulability analysis within a convex optimization framework to simultaneously assign periods and satisfy end-to-end latency constraints. Our approach is applied to an industrial case study as well as an example taken from the literature and is shown to be both effective and efficient.
1096901
Developing Evolutionary Cost Models for Query Optimization in a Dynamic Multidatabase Environment
Deriving local cost models for query optimization in a multidatabase system (MDBS) is a challenging issue due to local autonomy. It becomes even more difficult when dynamic environmental factors are taken into consideration. In this paper, we study how to evolve a cost model to capture a slowly-changing dynamic MDBS environment so that the cost model is kept up-to-date all the time. We propose a novel evolutionary technique, called the shifting method, to tackle this issue. The key idea is to adjust a cost model by adding the up-to-date performance information of a new sample query into and, in the meantime, removing the out-of-date information of the oldest sample query from consideration at each step. It is shown that this method is more efficient than the direct re-building approach. The relevant issues including derivation of recurrence update formulas, development of efficient algorithm, analysis of complexities as well as some aspects of implementation are studied. Our theoretical and experimental results demonstrate that the proposed shifting method is quite promising in deriving accurate evolutionary cost models for a slowly-changing dynamic MDBS environment.
11459525
Classifying Local Queries for Global Query Optimization in Multidatabase Systems
A multidatabase system (MDBS) integrates information from multiple pre-existing local databases. A major challenge for global query optimization in an MDBS is that some required local information a...
10306775
Piggyback Statistics Collection for Query Optimization: Towards a Self-Maintaining Database Management System
A database management system (DBMS) performs query optimization based on statistical information about data in the underlying database. Out-of-date statistics may lead to inefficient query processing in the system. The existing utility method, which collects statistics in batch mode, suffers from drawbacks such as heavy administrative burden, high system load and tardy updates. In this paper, we study approaches to performing statistical analysis on the fly during query execution, taking advantage of data already resident in main memory. We propose a framework for on-the-fly statistics collection, which we term piggybacking, and analyze the tradeoffs of piggybacking various statistics collection techniques on top of query execution plans. We present a multiple-granularity interleaving algorithm to integrate a set of piggyback operations with an execution plan, and show how the algorithm can be incorporated into an existing query optimizer. Our experiments demonstrate that useful statistics can be obtained via the piggyback method with a small overhead.