Mosaic models for textures

This paper deals with a class of image models based on random geometric processes. Theoretical and empirical results on properties of patterns generated using these models are summarized. These properties can be used as aids in fitting the models to images.     

Thinning algorithms for gray-scale pictures

Elongated black objects in black-and-white pictures can be ``thinned' to arcs and curves, without changing their connectedness, by (repeatedly) deleting black border points whose deletion does not locally disconnect the black points in their neighborhoods. This technique generalizes to gray-scale pictures if we use a weighted definition of connectedness: two points are ``connected' if there is a path joining them on which no point is lighter than either of them. We can then ``thin' dark objects by changing each point's gray level to the minimum of its neighbors' gray levels, provided this does not disconnect any pair of points in its neighborhood. Examples illustrating the performance of this technique are given.     

Migration Processes II: The Discrete Case

Following the study of migration processes in the continuous domain in Part I of this paper, we reformulate the concept of migration in the discrete domain (Z^m) and define Discrete Migration Processes (DMP). We demonstrate that this model is a natural discrete representation of the continuous model and maintains the model's features in a qualitative sense. We show that under discrete migration any discrete set shrinks to a limit in finitely many iterations. The discrete representation provides an advantageous basis for digitally implementing the MP model. Using this implementation we illustrate the discrete migration of various types of sets under various types of constraints.     

Nanoparticles of CdCl2 with closed cage structures

Nanoparticles of various layered compounds having a closed cage or nanotubular structure, designated also inorganic fullerene-like (IF) materials, have been reported in the past. In this work IF-CdCl₂ nanoparticles were synthesized by two methods. In one technique, a high temperature evaporation and subsequent condensation of dried cadmium chloride powder was used. In the other method, electron beam irradiation of the source powder led to its recrystallization into closed nanoparticles with a nonhollow core. The two methods are shown to produce nanoparticles of different topologies. While mostly spherical nested structures are obtained from the high temperature process, polyhedra with hexagonal or elongated rectangular characters are obtained by the electron beam induced process. The analysis also shows that, while the source (dried) powder is orthorhombic cadmium chloride monohydrate, the crystallized IF cage consists of the anhydrous 3R polytype which is not stable as bulk material in ambient atmosphere. Consistent with previous observations, this study shows that the seamless structure of the IF materials can stabilize phases, which are otherwise unstable in ambient conditions.     

Mid-infrared diffused planar waveguides made of silver halide chloro-bromide

We have developed waveguides for the mid-IR spectrum using silver halide crystals. Diffused planar waveguides constructed from silver chlorobromide (AgClBr) with different diffusion thicknesses were designed and characterized. The waveguides were based on our changing the refractive index of the guiding layer by a diffusion of Br- ions into crystalline AgCl substrates. The waveguides were analyzed and investigated with a 10.6-microm CO2 laser, and the optically measured thicknesses of the waveguides were found to vary between 65 and 600 microm. The propagation losses were in the range of 4-16 dB/cm, and the maximal entrance angle was 62 degrees. The output beam distribution was measured and was in good correlation with a numerical analysis simulation based on a ray-tracing model, by use of the eikonal equation.     

TEG—a hybrid approach to information extraction

This paper describes a hybrid statistical and knowledge-based information extraction model, able to extract entities and relations at the sentence level. The model attempts to retain and improve the high accuracy levels of knowledge-based systems while drastically reducing the amount of manual labour by relying on statistics drawn from a training corpus. The implementation of the model, called TEG (trainable extraction grammar), can be adapted to any IE domain by writing a suitable set of rules in a SCFG (stochastic context-free grammar)-based extraction language and training them using an annotated corpus. The system does not contain any purely linguistic components, such as PoS tagger or shallow parser, but allows to using external linguistic components if necessary. We demonstrate the performance of the system on several named entity extraction and relation extraction tasks. The experiments show that our hybrid approach outperforms both purely statistical and purely knowledge-based systems, while requiring orders of magnitude less manual rule writing and smaller amounts of training data. We also demonstrate the robustness of our system under conditions of poor training-data quality. Ronen Feldman is a senior lecturer at the Mathematics and Computer Science Department of Bar-Ilan University in Israel, and the Director of the Data Mining Laboratory. He received his B.Sc. in Math, Physics and Computer Science from the Hebrew University, M.Sc. in Computer Science from Bar-Ilan University, and his Ph.D. in Computer Science from Cornell University in NY. He was an Adjunct Professor at NYU Stern Business School. He is the founder of ClearForest Corporation, a Boston based company specializing in development of text mining tools and applications. He has given more than 30 tutorials on next mining and information extraction and authored numerous papers on these topics. He is currently finishing his book “The Text Mining Handbook” to the published by Cambridge University Press. Benjamin Rosenfeld is a research scientist at ClearForest Corporation. He received his B.Sc. in Mathematics and Computer Science from Bar-Ilan University. He is the co-inventor of the DIAL information extraction language. Moshe Fresko is finalizing his Ph.D. in Computer Science Department at Bar-Ilan University in Israel. He received his B.Sc. in Computer Engineering from Bogazici University, Istanbul/Turkey on 1991, and M.Sc. on 1994. He is also an adjunct lecturer at the Computer Science Department of Bar-Ilan University and functions as the Information-Extraction Group Leader in the Data Mining Laboratory.     

A method of detecting and tracking irises and eyelids in video

We locate the eye corners, eyelids, and irises in every frame of an image sequence, and analyze the movements of the irises and eyelids to determine changes in gaze direction and blinking, respectively. Using simple models for the motions of the head and eyes, we determine the head-independent motions of the irises and eyelids by stabilizing for the head motion. The head-independent motions of the irises can be used to determine behaviors like saccades and smooth pursuit. Tracking the upper eyelid and using the distance between its apex and the center of the iris, we detect instances of eye closure during blinking. In experiments on two short image sequences, in one of which the subject was wearing glasses, we successfully located the irises in every frame in which the eyes were fully or partially open, and successfully located the eyelids 80% of the time. When motion information in the form of normal flow was used, the irises were successfully tracked in every frame in which the eyes were fully or partially open, and the eyelids were successfully located and tracked 90% of the time.