A window-based method for automatic typographic parameter extraction

The synthesis of existing fonts with characters represented by parameterized structure elements requires determination of a set of font-specific global and local parameters. Parameters comprise, for example, the widths of vertical stems, horizontal bars and curved elements, the spacing between vertical stems, the relative position of the junction between arches and vertical bars and serif measures. These parameters need to be extracted from existing outline fonts. The paper presents a window based method for locating within existing outline characters the position of character features from which parameters can be measured. The method is based on the match between outline characters and their corresponding virtual skeleton

Coherent processing of character skeletal forms

It is well known that in the general context the similarity relation is very fuzzy and hard to define. Unfortunately, the intuitive notion of similarity is not a transitive relation: knowing that A is similar to B and that B is similar to C does not necessarily imply similarity between A and C. This is a main obstacle when trying to express formally what a coherent font design is. The authors suggest a method to decompose complex letter forms into simpler elements and suggest a formal transitive definition of a similarity relation between these elements. In the context of digital typography, this definition enables developing an algorithm to recover classes of similar elements within different characters of a given font. This knowledge is further exploited to ensure coherent type processing. For example, a modification (e.g. by a type designer) of a character element is propagated automatically to all the other characters that include a similar element. For the moment, the discussion is limited to the class of stroke font

Propagation of action potentials along complex axonal trees. Model and implementation.

Axonal trees are typically morphologically and physiologically complicated structures. Because of this complexity, axonal trees show a large repertoire of behavior: from transmission lines with delay, to frequency filtering devices in both temporal and spatial domains. Detailed theoretical exploration of the electrical behavior of realistically complex axonal trees is notably lacking, mainly because of the absence of a simple modeling tool. AXONTREE is an attempt to provide such a simulator. It is written in C for the SUN workstation and implements both a detailed compartmental modeling of Hodgkin and Huxley-like kinetics, and a more abstract, event-driven, modeling approach. The computing module of AXONTREE is introduced together with its input/output features. These features allow graphical construction of arbitrary trees directly on the computer screen, and superimposition of the results on the simulated structure. Several numerical improvements that increase the computational efficiency by a factor of 5-10 are presented; most notable is a novel method of dynamic lumping of the modeled tree into simpler representations ("equivalent cables"). AXONTREE's performance is examined using a reconstructed terminal of an axon from a Y cell in cat visual cortex. It is demonstrated that realistically complicated axonal trees can be handled efficiently. The application of AXONTREE for the study of propagation delays along axonal trees is presented in the companion paper (Manor et al., 1991)