Systems Seminar

Mathematical and Perceptual Models for Image Segmentation and Semantic Classification

Prof. Thrasos Pappas
EECS Department
Northwestern University


We present a new approach for semantic image analysis that combines knowledge of human perception with an understanding of signal characteristics to segment natural scenes into perceptually uniform regions, and then uses the region statistics to extract semantic information that can be used for intelligent and efficient image organization and retrieval. Our focus is on images of natural scenes. One of the challenges of this problem is that the statistical characteristics of perceptually uniform regions are spatially-varying due to effects of lighting, perspective, scale changes, etc. We present a new adaptive perceptual color-texture segmentation algorithm. Key segmentation parameters are determined on the basis of subjective tests. The color and texture features of the resulting regions are used as medium level descriptors, based on which we extract semantic labels. We also discuss the extension of these techniques to video, and in particular, spatiotemporal segmentation and background subtraction.


Thrasyvoulos (Thrasos) Pappas ( received the S.B., S.M., and Ph.D. degrees in electrical engineering and computer science from MIT in 1979, 1982, and 1987, respectively. From 1987 until 1999, he was a Member of the Technical Staff at Bell Laboratories, Murray Hill, NJ. In 1999, he joined the Department of Electrical and Computer Engineering (now EECS) at Northwestern University as an associate professor. His research interests are in image and video quality and compression, perceptual models for image processing, image and video analysis, model-based halftoning, and multimedia signal processing.

Thrasos is a Fellow of the IEEE and SPIE. He is a member of the Board of Governors of the Signal Processing Society of IEEE, and has served as chair of the IEEE Image and Multidimensional Signal Processing Technical Committee, associate editor of the IEEE Transactions on Image Processing, and technical program co-chair of ICIP-01 and IPSN-04 (Symposium on Information Processing in Sensor Networks). Since 1997 he has been co-chair of the SPIE/IS&T Conference on Human Vision and Electronic Imaging. He has also served as co-chair of the 2005 SPIE/IS&T Electronic Imaging Symposium.

Time and Place: Wed., Oct. 24, at 3:30 pm in 4610.


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