7507805
Locating the human eye using fractal dimensions
A new method for locating eye pairs based on valley field detection and measurement of fractal dimensions is proposed. Fractal dimension is an efficient representation of the texture of facial features. Possible eye candidates to an image with a complex background are identified by valley field detection. The eye candidates are then grouped to form eye pairs if their local properties for eyes are satisfied. Two eyes are matched if they have similar roughness and orientation as represented by fractal dimensions. We propose a modified approach to estimate the fractal dimensions that are less sensitive to lighting conditions and provide information about the orientation of an image under consideration. Possible eye pairs are further verified by comparing the fractal dimensions of the eye-pair window and the corresponding face region with the respective means of the fractal dimensions of the eye-pair windows and the face regions. The means of the fractal dimensions are obtained based on a number of facial images in a database. Experiments have shown that this approach is fast and reliable. This shows that the texture of the eyes can be represented very well by fractal surfaces.
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.
209064801
An accurate active shape model for facial feature extraction
28287084
Human face recognition based on spatially weighted Hausdorff distance
The edge map of a facial image contains abundant information about its shape and structure, which is useful for face recognition. To compare edge images, Hausdorff distance is an efficient measure that can determine the degree of their resemblance, and does not require a knowledge of correspondence among those points in the two edge maps. In this paper, a new modified Hansdorff distance measure is proposed, which has a better discriminant power. As different facial regions have different degrees of significance for face recognition, a new modified Hausdorff distance is proposed which is weighted according to a weighted function derived from the spatial information of the human face; hence crucial regions are emphasized for face identification. Experimental results show that the distance measure can achieve recognition rates of 80%, 87%, and 91% for the first, the first five, and the first seven likely matched faces, respectively.
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.
26133489
Robust Hausdorff distance for shape matching
The Hausdorff distance can be used to measure the similarity of two point sets. In matching the two point sets, one of them is translated, rotated and scaled in order to obtain an optimal matching, which is a computationally intensive process. In this paper, a robust line-feature-based approach for model-based recognition is presented, which can achieve good matching, even in a noisy environment or with the existence of occlusion. We propose three different ways for forming the line segments for a point set. Two of the methods are based on a fixed reference point, which are the centroid and the center of the minimal disk of the point set. The third method is based on the longest possible line segments formed within the point set. The line features extracted based on the respective line segments are insensitive to noise and can be used to determine the rotation and scale of the image point set accurately and reliably, and more importantly, 2D-2D matching algorithm can be adopted. The first 2D-matching is to compute the relative scale and orientation between the two point sets. Having rotated and scaled the image point set, the M-Estimation Hausdorff distance is applied for the second 2D-matching to measure the relative translation between the query point set and the model point set. This 2D-2D matching can greatly reduce the required memory and computation when compared to a 4D-matching. Both the performance and the sensitivity to noise of our algorithms are evaluated using simulated data. Experiments show that our 2D-2D algorithms can yield a high level of performance when determining the scale, the orientation and the similarity of two point sets.
9924554
Real-time multiple video player systems
In previous years, various real-time scheduling techniques have been proposed to improve the performance of a distributed multimedia system. However, not much work has been done on how a client player can play multiple videos concurrently. In this paper, we have designed a distributed multimedia system where a client player can play different videos at the same time. We introduce two mechanisms: priority assignment mechanism and feedback capture video mechanism for the system. The issues on how to implement the mechanisms in Windows NT are discussed. Experiments are conducted to investigate the performance of the proposed mechanism in Windows NT to study the most optimum configuration factors. We also define the monitoring factor and priority group mapping difference and study how they affect the overall system performance. From the results, we find that the mechanisms can effectively improve the system performance in terms of percentage of displayed frames.
11887466
On a partitioning problem
This paper investigates the problem of locating a set of “boundary points” of a large number of records. Conceptually, the boundary points partition the records into subsets of roughly the same number of elements, such that the key values of the records in one subset are all smaller or all larger than those of the records in another subset. We guess the locations of the boundary points by linear interpolation and check their accuracy by reading the key values of the records on one pass. This process is repeated until all boundary points are determined. Clearly, this problem can also be solved by performing an external tape sort. Both analytical and empirical results indicate that the number of passes required is small in comparison with that in an external tape sort. This kind of record partitioning may be of interest in setting up a statistical database system.
1690905
Broadcast of consistent data to read-only transactions from mobile clients
We study the inconsistency problem in data broadcast. While data items in a mobile computing system are being broadcast, update transactions may install new values for the data items. If the executions of update transactions and the broadcast of data items are interleaved without any control, it is possible that the mobile transactions, which are generated by mobile clients, may observe inconsistent data values. We propose a new algorithm, called Update-First with Order (UFO), for concurrency control among the mobile transactions and update transactions. The mobile transactions are assumed to be read-only. In the UFO algorithm, all the schedules among them are serializable. Two important properties of the UFO algorithm are that: (1) the mobile transactions do not need to set any lock before they read the data items from the "air"; and (2) its impact on the adopted broadcast algorithm, which has been shown to be an efficient method for data dissemination in mobile computing systems, is minimal.
17880514
Concurrency Control for Mobile Systems with Data Broadcast
Although data broadcast has been shown to be an efficient method for disseminating data items in a mobile computing system with large number of clients, the issue on how to ensure the data consistency observed by mobile transactions, which are generated by mobile clients, has been largely ignored by researchers in the area. While data items are being broadcast, update transactions may install new values for the data items. If the executions of update and broadcast of data items are interleaved without any control, the mobile transactions may observe inconsistent data values. In this paper, we propose a serialization checking method (SCM) for concurrency control between read-only mobile transactions and update transactions. SCM is based on the framework of an earlier algorithm, Update First with Ordering (UFO), but improves on that algorithm by reducing re-broadcast overhead when the probability of data conflict between updates and data broadcast is high. Simulation experiments have been performed to investigate the performance characteristics of the proposed method.
13891436
Adaptive Real-Time Monitoring Mechanism for Replicated Distributed Video Player Systems
One of the main problems to ensure the quality of services (QoS) in video playback in a replicated distributed video player system is how to adapt to the changing network traffic condition and the workload at the video servers. In this paper, we propose a mechanism, called adaptive real-time monitoring, to solve the problem. The proposed mechanism consists of three steps: selection, monitoring and switching. In the selection step, the mechanism will determine which video server to serve the client by considering the factors of the current network traffic and workload at the servers. In the monitoring step, the QoS of the video playback will be monitored closely. A feedback mechanism is adopted to improve the QoS of video playback by adjusting the allocation of resources at the video server. The switching mechanism will be invoked when the QoS of the video display is too worse that it must switch to another video server.