[Jozsef Vass]

Jozsef Vass' Home Page

Contact Information

Jozsef Vass
201 Engineering Building West
Department of Computer Engineering and Computer Science
University of Missouri-Columbia
Columbia, MO 65211
Tel: (573) 884-6049 (office), (573) 882-6265 (lab)
Fax: (573) 882-8318
E-mail: vass@cecs.missouri.edu


    Ph.D., Computer Engineering and Computer Science
        University of Missouri-Columbia, (expected)
        GPA: 4.0/4.0
        Thesis: Novel Compression Strategies in  Multimedia Communications over Wireless and Wireline Networks

    M.Sc., Electrical and Computer Engineering
       University of Missouri-Columbia, Dec. 1996
        GPA: 4.0/4.0
        Thesis: Toll Quality Low Bit Rate Speech Coding and Morpho-Subband Image Coding

     Dipl. in Electrical Engineering
       Technical University of Budapest, June, 1995
        GPA: 4.63/5.0
        Thesis: Robustness of Feature Extracted Parameters in Speech Processing (in Hungarian)

Completed Courses

Research Projects

I have been participated in several very interesting research projects:

3-D Graphics Compression. Applying wavelet decomposition to a triangular mesh is a significant challenge. After wavelet decomposition, wavelet coefficients will be transmitted in order of importance.

Landcover and Landuse Automatic Classification. Currently, Landcover and Landuse classification is semi-automatically carried out by MoRAP for the state of Missouri. We are developing automatic algorithms that can significantly speed up this process. Our research directions include Bayesian classification with learning combined with Gaussian mixture density modeling.

Video Communications over Wireless and Wireline Networks. For wireless case, we have developed a proxy-based system, where the video is adapted to the hardware capabilities and network resources of individual mobile hosts. For efficient video transmission, we our three-dimensional significance-linked connected component analysis (3D-SLCCA). Error resilience is ensured by our channel coding technique. For wireline case, we are studying 3D-SLCCA transmission over ATM networks.

Channel Coding Robust significance-linked connected component analysis is developed by integrating our SLCCA image coding scheme with multilayer error protection strategy that includes synchronization, unequal error protection, retransmission, and error concealment. Wavelet-based Video Compression. Two algorithms were developed for video communications, video significance-linked connected component analysis (VSLCCA) and three-dimensional significance-linked connected component analysis (3D-SLCCA). In VSLCCA, fine-tuned motion estimation and exhaustive overlapped block motion compensation ensures both blocking-effect-free error frames and small prediction error thus wavelet transform can be efficiently applied. Significant wavelet coefficients are represented by SLCCA algorithm. VSLCCA provides superior performance to H.263. VSLCCA was also implemented as a JAVA applet and a standalone application using Motif. (More information.) In 3D-SLCCA both the wavelet transformation and SLCCA data organization and representation strategy is extended to 3-D. In addition to high coding efficiency, 3D-SLCCA provides scalability, low computational complexity, and error resilience. 3D-SLCCA outperforms 3D-SPIHT. Wavelet-based Image Compression. In the MCVL, we have developed a high performance image coding algorithm termed significance-linked connected component analysis (SLCCA). SLCCA outperforms Shapiro's embedded zerotree wavelet (EZW), Servetto et al. 's morphological representation of wavelet data (MRWD) and Said and Pearlman's set partitioning in hierarchical trees (SPIHT) as well. It is among the best wavelet coding algorithms publish in the literature. (More information) Image Database Retrieval. By using a unified image compression algorithm for storing images, indexing, and retrieval, the database management functionalities may be significantly reduced. In this research, we have chosen SLCCA as a the underlying compression algorithm, and features used for indexing are directly extracted from the SLCCA bitstream. The main research directions include 1) progressive image transmission, 2) interactive search refinement, and 2) dynamic scalable features. (More information) Object-based Video Coding. The emerging MPEG-4 standard composes the scene of meaningful audio-visual objects. In the case of natural sequences, the main problem is image segmentation. We attack this problem by composing temporal and spatial segmentation known as spatio-temporal segmentation. Nonlinear Subband Decomposition. In the MCVL, we have developed a low bit rate Morpho-Subband Image Coding Scheme. The developed algorithm outperformed Egger et al. 's adaptive subband decomposition (ASD) (O. Egger, W. Li, and M. Kunt, "High compression image coding using an adaptive morphological subband decomposition," Proc. IEEE, vol. 83, no. 2, pp. 272-287, Feb. 1995) by 2.71 dB for the Lena image at 0.16 bits-per-pixel. Speech Coding. Since my focus in Hungary was speech processing my first project was speech coding. I have developed a high performance Linear Predictive Coding (LPC) quantization scheme that was applied to CELP FS1016 speech coder and superior results were obtained when compared to the original quantizer.

Professional Activities

Reviewer for IEEE Transactions on Circuits and Systems for Video Technology
Reviewer for IEEE Speech and Audio Processing
Reviewer for IEEE Systems, Man, and Cybernetics
Reviewer for IEEE Signal Processing
Reviewer for Image Communications
Reviewer for International Journal of Adaptive Control & Signal Processing
Reviewer for Pattern Recognition Letters
Reviewer for ACM WoWMoM'99, MobiCom'98

System Administration

Besides my research, I am also the System Administrator of the Multimedia Communications and Visualization Laboratory. I have set up and manage 15 SGI workstations (1 Onyx2, 4 Octanes, 8 O2s, and 2 Indigo2s). This work includes both hardware and software support, replacing defected hardware, installing patches, and licensing softwares. In addition I am also the Webmaster of the MCVL.


List of publications

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