Accession Number : AD0714594

Title :   PADEL - A Pattern Description Language.

Descriptive Note : Technical rept.,

Corporate Author : OHIO STATE UNIV COLUMBUS ELECTROSCIENCE LAB

Personal Author(s) : Breeding,Kenneth J.

Report Date : JUN 1970

Pagination or Media Count : 44

Abstract : A large class of optical pattern recognition problems may be described in terms of line drawings. Such line drawings are particularly amenable to the composition of strings of descriptors which may be processed in many ways to produce picture rotations, reflections and others as well as to extract pattern features. The paper describes line drawings in symbol strings. The language is a tranformational grammar in which elements of the line drawing, or picture, correspond to elements in the description. The correspondence is reversible so that given a grammatically correct string in PADEL a line drawing may be constructed. Using the language, several topological transformations are described in which the picture is modified by simple manipulation of the strings. First the simple tranformations of rotations, reflections, and scale changes are described. Then a non uniform, one dimensional scale changes is described in which the pictures scale is changed along one axis only. This may be termed 'rubber sheet warping'. Finally the process of identifying pattern features is described. It is then shown how PADEL may be applied to the recognition of fixed oriented line drawings. Thus, the language is shown to be very useful in recogniaing hand printed alpha numeric characters. Examples of this recognition process are given. (Author)

Descriptors :   (*PROGRAMMING LANGUAGES, DESIGN), (*PATTERN RECOGNITION, DATA PROCESSING), TOPOLOGY, ALGORITHMS, IMAGES, ROTATION, SYMBOLS, SYNTAX, IDENTIFICATION, PROJECTIVE GEOMETRY, VISUAL PERCEPTION, CHARACTER RECOGNITION, COMPUTER PROGRAMMING

Subject Categories : Computer Programming and Software
      Computer Hardware

Distribution Statement : APPROVED FOR PUBLIC RELEASE