12206604
An adaptive active contour model for highly irregular boundaries
Abstract Snake is an active contour model for representing image contours. In this paper, we propose an efficient active contour model which can represent highly irregular boundaries. The algorithm includes an adaptive force along the contour, and adjusts the number of points for the snake according to the desired boundary. A better stopping criterion based on the area of a closed contour is devised. Furthermore, in this method, a contour can break automatically to represent the contours of multiple objects. Experiments show that this method can extract object's boundaries accurately and efficiently.
5893059
Hybrid Chinese/English text detection in images and video frames
We propose a multiscale texture-based method using local energy analysis for hybrid Chinese/English text detection in images and video frames. Local energy analysis has been shown to work well in text detection, where remarkable local energy variations of pixels correspond to text region or boundary of other objects and lower local energy variations of pixels correspond to background or the interior of non-text objects. Local energy variation is calculated in a local region based on the wavelet transform coefficients of images. Hybrid Chinese/English text in images and video frames can be detected whether it is aligned horizontally or vertically. The font size of text to be detected may vary in a wide range of values. The proposed method has been tested on 321 frame images obtained from local TV programs and a tested dataset with low missed rate and false alarm rate.
31880885
Channel-adaptive error protection for streaming stored MPEG-4 FGS over error-prone environments
In this paper, we investigate an adaptive channel error-protection scheme for streaming stored MPEG-4 fine granular scalability (FGS) bitstreams over error-prone environments. The human eye is sensitive to the variations in reconstructed image quality. Therefore, instead of using only the minimal average frame distortion as the optimization criterion, we propose a rate-distortion (R-D)-based bit-allocation method to determine the source coding rate and the channel coding rate under a given channel condition so as to minimize both the average image distortion and quality variation. Based on our proposed piecewise model of the MPEG-4 FGS enhancement layer, a balance between the average frame quality and quality variation will be obtained. Experimental results show that, compared with other existing methods, our proposed method can achieve less quality variation and comparable average frame distortion under various channel conditions.
39178482
Illumination invariant face recognition
The appearance of a face will vary drastically when the illumination changes. Variations in lighting conditions make face recognition an even more challenging and difficult task. In this paper, we propose a novel approach to handle the illumination problem. Our method can restore a face image captured under arbitrary lighting conditions to one with frontal illumination by using a ratio-image between the face image and a reference face image, both of which are blurred by a Gaussian filter. An iterative algorithm is then used to update the reference image, which is reconstructed from the restored image by means of principal component analysis (PCA), in order to obtain a visually better restored image. Image processing techniques are also used to improve the quality of the restored image. To evaluate the performance of our algorithm, restored images with frontal illumination are used for face recognition by means of PCA. Experimental results demonstrate that face recognition using our method can achieve a higher recognition rate based on the Yale B database and the Yale database. Our algorithm has several advantages over other previous algorithms: (1) it does not need to estimate the face surface normals and the light source directions, (2) it does not need many images captured under different lighting conditions for each person, nor a set of bootstrap images that includes many images with different illuminations, and (3) it does not need to detect accurate positions of some facial feature points or to warp the image for alignment, etc.
15640953
Frequency layered color indexing for content-based image retrieval
Image patches of different spatial frequencies are likely to have different perceptual significance as well as reflect different physical properties. Incorporating such concept is helpful to the development of more effective image retrieval techniques. We introduce a method which separates an image into layers, each of which retains only pixels in areas with similar spatial frequency characteristics and uses simple low-level features to index the layers individually. The scheme associates indexing features with perceptual and physical significance thus implicitly incorporating high level knowledge into low level features. We present a computationally efficient implementation of the method, which enhances the power and at the same time retains the simplicity and elegance of basic color indexing. Experimental results are presented to demonstrate the effectiveness of the method.
209064801
An accurate active shape model for facial feature extraction
16685984
A multi-version data model for executing real-time transactions in a mobile environment
With the significant advances in mobile computing technology, there is an increasing demand for various mobile applications to process transactions in a real-time fashion. When remote data access is considered in a mobile environment, data access delay becomes one of the most serious problems in meeting transaction deadlines. In this paper, we propose a multi-version data model and adopt the relative consistency as the correctness criterion for processing of real-time transactions in a mobile environment. The purpose is to reduce the impacts of unpredictable and unreliable mobile network on processing of the real-time transactions. Under the proposed model, the overheads for concurrency control can be significantly reduced, and the data availability is much enhanced even under network failures. A real-time transaction may access stale data, provided that they are relatively consistent with the data accessed by the transaction, and the staleness of the data is within the requirements. An image transaction model, which pre-fetches multiple data versions at fixed hosts, is proposed to reduce the data access delay and to simplify the management of the real-time transactions in a mobile environment. The image transaction model also helps in reducing the transaction-restart overheads and minimizing the impacts of the unpredictable performance of mobile network on transaction executions.
17018329
An efficient method for generating location updates for processing of location-dependent continuous queries
Recent advances in mobile computing and mobile communication technology have led to the emergence of many innovative mobile computing applications. Some of them require providing support to location-dependent continuous queries (LDCQs) on moving objects. The result of a location-dependent query depends on the current locations of the moving objects. When the query is specified as continuous, the requesting client can get continuously changing results. In order to provide correct and timely results to requesting clients, the locations of moving objects have to be closely monitored. In this paper, we propose an adaptive monitoring method (AMM) for managing the locations of moving objects to maintain the correctness of the results of query evaluation without significantly increasing the wireless bandwidth requirements. Extensive simulation experiments have been conducted to investigate the performance of the proposed method as compared to plain dead-reckoning (PDR).
12783795
Strategies for resolving inter-class data conflicts in mixed real-time database systems
Although many efficient concurrency control protocols have been proposed for real-time database systems, they are mainly restricted for systems with a single type of real-time transactions or a mixed set of soft real-time and non-real-time transactions only. Their performance objective usually aims at the minimization of the number of missed deadlines of soft real-time transactions or to guarantee the deadline satisfaction of hard real-time transactions. So far, it is still lack of any good study on the design of concurrency control strategies for mixed real-time database systems (MRTDBS), which consist of both hard and soft real-time transactions, and together with non-real-time transactions. Due to the very different performance requirements of hard and soft real-time transactions, existing real-time concurrency control protocols may not be suitable to MRTDBS. In this paper, we propose strategies for resolving data conflicts between different types of transactions in an MRTDBS so that the performance requirements of each individual transaction type can be satisfied and, at the same time, the overall system performance can be improved. The performance of the proposed strategies is evaluated and compared with a real-time optimistic approach, which has been shown to give a better performance than the lock-based protocols for soft and firm real-time transactions.
42469158
Concurrency control for real-time database systems with mixed transactions
This paper proposes a real-time concurrency control protocol called Reduced Ceiling Protocol (RCP) for database systems consisting of hard and soft real-time transactions. In the RCP, the schedulability of hard real-time transactions is guaranteed by reserving the data items for them and by eliminating the blocking time from soft real-time transactions. Different concurrency control strategies are used to resolve the data conflicts between different combinations of hard and soft real-time transactions. We have shown the characteristics of the schedules generated from the RCP. Simulation experiments have been performed to study the performance of the RCP as compared with the optimistic concurrency control with broadcast commit (OCC-BC). It has been found that the RCP can guarantee the performance of the hard real-time transactions and at the same time reduce the number of deadline missing of the soft real-time transactions.
30747843
Future Directions
decade she has taught cataloger training workshops, particularly in cataloging Internet resources. Before coming to Stanford, Greta was the Authority Control Librarian and head of the Quality Control Unit at WLN. She is also a silent film historian and serves as the librarian at the Niles Essanay Silent Film Museum, as well as maintaining a website on silent film actresses.