PAX(ID:7274/)Picture representation language for Cloud Chambersfor PArallel processing simulator (where does the X come in?) Language for reprenting bubble-chamber pictures, used for the BUBBLE-SCAN system at U Illinois and U Maryland Hardware:
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References: The illustrations presented show that reasonably satisL factory results were obtained, although the 1 bit photograph yielded results that were distinctly inferior to handsketching in the smoothness of contour formation. The processes are surely relevant to pattern enhancement and pattern recognition problems. Investigators in this area may find it well worthwhile to investigate PAX. in ACM Computing Reviews 7(01) January-February 1966 view details Introduction Recent active interest in the area of graphic data-based "conversation programs" has pointed up the urgent need for sophisticated picture processing models in a convincing manner. Kitsch has very ably argued that "from the point of view of computer information processing, the important fact about natural language text and pictures is that both have a syntactic structure which is capable of being described to a machine and of being used for purposes of interpreting the information within a data processing system." "The problem of how to describe the syntactic structure of text and pictures and how to use the syntactic description in interpreting the text and pictures" has been tackled in a certain specific way by Kirsch and his coworkers. For over three years now the author has been actively engaged in investigating the possibilities of syntax-directed interpretation of classes of pictures The immediate problem that was tackled was the development of a computer program for the automatic scanning of bubble chamber negatives. One was fortunate, in a certain basic sense, that one's first introduction to picture processing was through bubble chamber pictures and not alphanumeric characters. For it became clear from the very beginning that an appeal to most of the existing pattern recognition models would not only not work, but the models themselves were basically inadequate. These models are based on the categorization of images as belonging to one or another of a finite set of prototypes. Bubble chamber picture scanning defines a context for visual data processing and pattern recognition in which the concepts "prototypes" and "images" become virtually meaningless. It was clear very soon that what was needed to cope with the problem on hand was a descriptive scheme in terms of which the structural features of individual bubble chamber pictures could Ee efl/eiently described and talked about. Pattern recognition is only one aspect of the nmch more fundamental problem of analysis and description of classes of patterns (or equivalently, classes of pictures). The aim of any adequate recognition procedure should be not merely to arrive at a "yes," "no," "don't know" decision but to produce a structured description of the input picture. The author has argued elsewhere at some length that no processing model could hope to accomplish this in a satisfactory way unless it has built into it, in some sense, a generative grammar for the class of patterns it is set up to analyze and recognize. For the bubble chamber scanning program we worked out a processing model, called the syntactic model, and a programming language, called the parallel processing language, in which picture processing algorithms based on the above model could be designed and described. An interpreter for this language was designed for the University of Illinois IBM 7094-1401 system, and using this a very wide variety of picture processing algorithms was investigated. A first version of a scanning program, BUBBLE SCAN I, based on this model and using the above programming language was successfully completed [5]. Later, the structure of a "conversation" program, BUBBLE TALK, for use in the context of bubble chamber pictures was worked out in considerable detail. Most of this work, except for two papers, exists as yet only in the form of internal technical reports. Outlined briefly in Section 2 of this paper are the syntactic model and the processing details, with specific reference to bubble chamber pictures. In Section 3 the environment in which the "conversation" program is intended to function is described and it is indicated how the program is set up to make use of the syntactic details generated by the parallel processor. The interpreter for the parallel processing language has been rewritten for the CDC 3600 computer system and named COMPAX. In Section 4 a generative grammar for a subset of "handprinted" letters of the English alphabet is described and a few computer-generated specimens using COMPAX and this generative grammar are exhibited. Appendix I contains a summary of the features incorporated in COMPAX and its basic specifications. Extract: Concluding Remarks Concluding Remarks In this paper, a specific metatheoretic model for the analysis and description of classes of pictures has been considered. A particular class of processing procedures, termed parallel processing algorithms, has been referred to, and it has been shown how, in terms of labeling schemata based oil these techniques, appropriate descriptive statements concerning specific pictures belonging to a given class can be generated. The power and scope of the model and the parallel processing techniques has been illustrated by considering in some detail two different classes of pictures: bubble chamber pictures, and "handprinted" letters of the English alphabet. The unifying factor in all the above has been the view that adequate descriptive schemes that can cope with the analysis of classes of pictures should also prove to be naturMly embeddable in larger systems within which conversation, in some version of a natural language, can be conducted about pictures belonging to these classes. Syntax-directed interpretation of pictures meets this adequacy criterion in a satisfactory way, as has been seen in this paper. But, in the author's opinion, the nmeh more fundamental significance of syntax-directed picture processing models lies in the possibility they offer for constructing a theory of a "General Problem Solver" that can deal with linguistic data and pictorial (or visual) data in an integrated and uniform manner. One cannot emphasize too strongly that working out an adequate metatheory for "problem solving behavior" is really the basic problem of artificial intelligence, and it still remains very nmeh an open problem. Extract: COMPAX - Preliminaries COMPAX - Preliminaries COMPAX is the name of a parallel processing simulator that has been designed and coded for the CDC 3600 system at the Tata Institute of Fundamental Research, Bombay [8]. In writing COMPAX, full advantage has been taken of the already existing simulator PAX for the IBM 7094 system at the University of Illinois. In this appendix, a brief description of COMPAX and the special features incorporated in it is given. The pseudo-machine simulated by COMPAX consists of five units : (1) The plane memory is a stack of 51 planes, each plane consisting of a 96 X 96 array. Sometimes this memory is visualised as consisting of 9216 Z-words (or columns) of 51 bits each. (2) A conventional memory used for storing COMPAX code, 3600 code, direction lists, coordinate pairs, and similar information. (3) Logical units capable of performing operations on planes such as shifting, thresholding, various set-theoretic operations, and index arithmetic operations. (4) A control unit which interprets the COMPAX code, as well as the 3600 code and carries out the processing defined by them. (5) An I/0 device for transmitting digitized, pictorial information (i.e., planar, array of bits) and an additional output device for transmitting ancillary information. The 51 planes of the plane-memory are designated by symbolic names P0, P1, "'" , Ps0. Plane names enter as arguments in COMPAX instructions. For mnenmnic purposes the programmer can assign and use "arbitrary" identifiers as names of planes. Although the parallel processing instructions themselves treat an entire plane (96 X 96 array) as a single operand, it is sometimes necessary to refer to and operate on individual points of a specified plane. The points are referred to by their coordinates. The lower left bit has the coordinates (0, 0), and the upper right, (95, 95). A coordinate pair can be stored in a single location of the conventional memory. There are 8 immediate neighbors to every point in ~ plane. These are individually identified by 8 direction numbers: d = 1, 2, - ? ? , 8. The 1-neighbor is the East-neighbor, and the numbering runs counterclockwise, d = 0 denotes the point itself (i.e., the self). A direction list, DL, is a list of direction numbers, and specifies a subset of the immediate neighbors. A direction list enters into a COMPAX instruction much as a parameter does in a conventional instruction. A DL can be assigned and identified by a symbolic name. The simulator has 25 built-in registers IR1, IR2, ... , IR25, for counting and indexing purposes. The first 7 of these can be used for indexing, i.e., the modification of an instruction argument at execution time. Extract: COMPASS and COMPAX COMPASS, the assembly language of the 3600 system, forms a subset of COMPAX, SO that a programmer can interleave COMPAX code with COMPASS code. in [ACM] CACM 9(03) March 1966 includes proceedings of the ACM Programming Languages and Pragmatics Conference, San Dimas, California, August 1965 view details Extract: Software Software The nature of the software used in an interactive image processing system will depend greatly on the ma-chine being used, the programm3-ng talent available, and the types of processing operations to be performed. Several major packages of image processing programs are available. Two notable examples are Vicar, developed by California Institute of Technology's Jet Propulsion Laboratory, and PAX, developed by the Universities of Illinois and Maryland. These packages are usually embedded in a high-level language such as Fortran. The examples given in this paper were programmed in PAX. The nature of the software used in an interactive image processing system will depend greatly on the ma-chine being used, the programm3-ng talent available, and the types of processing operations to be performed. Several major packages of image processing programs are available. Two notable examples are Vicar, developed by California Institute of Technology's Jet Propulsion Laboratory, and PAX, developed by the Universities of Illinois and Maryland. These packages are usually embedded in a high-level language such as Fortran. The examples given in this paper were programmed in PAX. Extract: PAX PAX is a collection of over 100 basic image processing routines that can be called from Fortran programs [5]. Originally a simulator for the ILLIAC III computer, versions of PAX for several different machines are available, notably the IBM 7094 and 360/370 (50 and above); Univac 1108; CDC 3600 and 6600; and DEC-10. in [ACM] CACM 9(03) March 1966 includes proceedings of the ACM Programming Languages and Pragmatics Conference, San Dimas, California, August 1965 view details in [ACM] CACM 9(03) March 1966 includes proceedings of the ACM Programming Languages and Pragmatics Conference, San Dimas, California, August 1965 view details Research into the interpretation of graphics has been motivated primarily from two sources. The first is simply the desire to realise in man-machine communication the kind of descriptive power supported by the use of graphics in man-man communication. The second springs from working with a data base of information which is most conveniently recorded in graphical form (e.g. maps, engineering drawings, etc.). The quality associated with this kind of interpretation is captured by the idea of the 'machine perception of graphics'. The acceptance of this idea places computer graphics and with it, graphic languages, in a cognate position with respect to picture interpretation and scene analysis, although there are, of course, important differences. The body of the paper is concerned with reviewing the status of graphical languages given that the task for which they have to be suited is one of interpretation. in Nake, F. and Rosenfeld, A. "Graphic Languages" Amsterdam: North-Holland Publishing Company 1972. view details A rather different tack of "two-dimensional" language development is represented by Pax [Johnston, 1970] and Compax [Narasimhan, 1966]. These are onedimensional languages with facilities to manipulate truly two-dimensional data. The basic data are matrices of zeros and ones, called planes, which represent white and black spots of a picture. Various set- and graph-theoretic operations on these planes, which have the normal Euclidean connectivity properties, are available. The abstract machine on which Compa× is based assumes both a two-dimensional memory for the storage of the planes and an input/ output device for transmitting the digitized pictorial information. The advantage of these languages is of course that we think directly in terms of the two-dimensional structures. Also, there is much parallelism implied by the operations which can be exploited by properly designed hardware. in Proceedings of the SIGPLAN symposium on Two-dimensional man-machine communication 1972 , Los Alamos, New Mexico, United States view details Vicar stores pictures as either real or integer arrays; in the latter case, the values of one or more pixels can be stored in a single machine word. This format permits fast execution of arithmetic operations on pictures using hardware instructions; it is thus very appropriate for image compression anti enhancement work, which usually involves many such operations. The use of real arrays is important if the processing being done involves Fourier transforms or the like; if one truncates the values in a transform to integers, useful information may be lost. Pax stores pictures as stacks of "bit planes"; the ith bit plane in such a stack is a binary array consisting of the ith bits of the pixel gray levels. One advantage of this format is that any number of "overlays," representing segments extracted from a picture, can be stored "in registration" with the picture by adding planes to the stack. Execution of logical operations on the binary planes is fast, since hardware instructions can usually be used to perform such operations on all bits of a machine word -- hence, on many pixels -- simultaneously. Thus, Pax is an appropriate system for scene analysis work involving many operations on picture seg- ments. Picture processing can often be greatly facilitated by using special hardware array processors. A variety of analog devices for processing images have also been proposed. In particular, many useful picture-processing operations can be performed optically, but a discussion of nondigital processing techniques is beyond the scope of this article. in Encyclopedia of Computer Science, Ralston, Anthony, and Meek, Chester L. (eds) New York, NY Petrocelli/Charter 1976 view details |