Computer Science

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Dr. Ramazan S. AygŁn

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Multimedia Databases

Although computer vision and image processing techniques improved significantly, the subjective user evaluation of video and image data as well as unsatisfactory object recognition methods made it necessary incorporation of fuzzy, uncertain, and imprecise data in multimedia databases. The multimedia database systems have to enable information for an attribute at different levels of uncertainty and support querying with fuzzy and crisp values independent of how data is stored in the database. We have developed a conceptual database model for multimedia database applications using ExIFO2 data model [15] and used Fuzzy Object Oriented Model (FOOD) as the logical model. This multimedia database is applied for videos of soccer games [3].

Multimedia Networking

The data whether stored in the database or not has to be transmitted over networks shared by many users. The congestion of the network and the compressed video data affect the quality of presentations drastically. Especially, the loss of a frame does not only affect the display of the frame, it also affects the display of the dependent frames. We have proposed a Probe-loss utilization streaming (PLUS) mechanism to reduce the loss of high priority frames [2]. For an MPEG video stream, I frames have the highest priority and B frames have the lowest priority. The status of the network is probed with B frames andI frames are protected in a better way by reducing the congestion caused by the system. We have built a client server middleware design strategy for streaming multimedia presentations [1].

Interactive Multimedia Presentation Management

The user interactions are core elements of multimedia presentations. The loss and delay of the data over networks complicates the synchronization if user interactions that change the course of the presentations are enabled. The event-based or constraint-based synchronization models provide powerful mechanism to handle synchronization in distributed systems. However, the interactions like skip and backward usually complicates the synchronization and the specification of the synchronization. We have proposed a rule-based synchronization model based on Event-Condition-Action (ECA) rules [10, 14]. These rules can be specified by a rule definition language or can be extracted from SMIL expressions [12]. The necessary constraints or rules for user interactions are automatically extracted by the system and may be updated by the author.

Model Checking

One major question is whether the specified multimedia presentation is correct or not. A synchronization specification may yield different results on different presentation tools. It is important whether the presentation is actually played correctly by the synchronization model. The specification properties have also to be checked based on the synchronization model. The multimedia systems are usually tested by simulation or by conducting experiments. Nevertheless, in these cases it is not possible to cover all cases and sometimes mistakes can be costly. We eventually applied model checking techniques on multimedia synchronization. The synchronization rules are converted to PROMELA language and the properties are verified by the SPIN model checker [4,11]. Consequently, the author is guaranteed to develop correct presentations.

Video Processing

Most of the multimedia research is devoted on video. The video data challenges researchers in compression, information retrieval, and transmission and led many research areas. We have developed a novel video application to spatially browse recorded video data [5]. The users are allowed to perform pan left and right, tilt up and down, and zoom in and out, if the necessary information can be extracted from various portions of the video. This requires high resolution sprite (mosaic) generation, reduction of blurring in the sprite, fast motion estimation and compressed domain processing to decrease processing cost [6, 7, 8, 9]. We have developed a tool named as VideoCruise to spatially browse videos [5]. We have tested this tool for distance education application. We have integrated video browsing tool, synchronization model for user interactions and PLUS under a multimedia system.

Bioinformatics

Heterotrimeric G proteins interact with G protein-coupled receptors in response to stimulation by hormones, neurotransmitters, chemokines, and sensory signals to intracellular signaling cascades. We provide a robust computational method for finding new G proteins and their homologs using SVM based pattern recognition algorithm.

 

 

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