Showing papers by "Azriel Rosenfeld published in 1973"

Angle Detection on Digital Curves

Abstract: A simple parallel procedure for selecting significant curvature maxima and minima on a digital curve is described.

Arcs and Curves in Digital Pictures

Abstract: Characterizations of digital “simple arcs” and “simple closed curves” are given. In particular, it is shown that the following are equivalent for sets S having more than four points: (1) S is a simple curve; (2) S is connected and each point of S has exactly two neighbors in S; (3) S is connected, has exactly one hole, and has no deletable points. It follows that if a “shrinking” algorithm is applied to a connected S that has exactly one hole, it shrinks to a simple curve.

Progress in Picture Processing: 1969--71

Abstract: : Developments in the field of picture processing by computer during 1969-71 are surveyed. The topics covered include picture compression, image enhancement, pictorial pattern recognition, scene analysis, and picture grammars. (Author)

Array grammar normal forms

Abstract: The language of an array grammar has been defined as the set of finite, connected terminal arrays, surrounded by #'s, that can be derived from an initial S surrounded by #'s. In the first section of this paper, it is shown that any array language has an array grammar in which all terminal arrays are in fact connected; and that the set of terminal, finite connected components of non #'s that occur in the sentential forms of any array grammar is an array language. Thus several possible ways of defining an array language are in fact all equivalent. In the second section of the paper, it is shown that array grammars need not use #'s as context. It is also shown that array grammars which start with arbitrary initial arrays of S's, and neither create nor destroy #'s, have exactly the same power as monotonic array grammars. In the third section, parallel array grammars are defined, and it is shown that any (monotonic) sequential array language is a (monotonic) parallel array language and vice versa.

Gray-Level Manipulation Experiments for Texture Analysis

Abstract: Some gray-level manipulation techniques are described, the first of which involves changing the gray-level distribution within the picture. Thereafter a method for extracting relatively noise-free objects from a noisy background is described. The purpose of these techniques is to preprocess a textural scene for subsequent analysis or classification. The present state of the art of texture analysis in general does not enable the parameters associated with the techniques to be generalized. Results for a range of parameters for both real and computer-generated pictures are therefore given.

A region coloring technique for scene analysis

Abstract: A method of converting a picture into a “cartoon” or “map” whose regions correspond to differently textured regions is described. Texture edges in the picture are detected, and solid regions surrounded by these (usually broken) edges are “colored in” using a propagation process. The resulting map is cleaned by comparing the region colors with the textures of the corresponding regions in the picture, and also by merging some regions with others according to criteria based on topology and size. The method has been applied to the construction of cloud cover maps from cloud cover pictures obtained by satellites.

An array grammar programming system

Abstract: A package of Fortran programs has been developed that permits a user to interactively design and test array grammars. The user can control the rule selection procedure in a derivation or parse, using weighted programming matrices; he also has a choice of instance selection schemes (raster, random, parallel). Examples are given involving array languages consisting of simple geometrical patterns, as well as a language of “neuron pictures.”

Digital Picture Processing: A Guide to the Literature.

Abstract: : The report consists of several parts of a forthcoming book on Digital Picture Processing, dealing with pictures and their computer representation, image enhancement, and picture matching. (Author)