A CCD-based imaging system has been developed for the White Light Coronagraph/X-Ray XUV Telescope experiment on the International Solar Polar Mission, The flight system supports two separate focal plane CCDs, one of which is an 800 x 800 pixel array for white light detection, the other a 256 x 320 device for the 8-750 Å band. Each CCD has its own dedicated clocking circuitry and preamplifier. Each employs correlated double sampling, Once the output signals are beyond the amplification stages, however, both devices use the same processing hardware. The flight system is controlled by an on-board microprocessor which compresses, formats and buffers the data for acquisition by the telemetry system, A breadboard system which uses a minicomputer as controller and image processor has been assembled and tested, This system has been used to evaluate the sensitivity and imaging characteristics of several CCDs, Sample results of X-ray and XUV illuminations are shown. The minicomputer system supports not only bench testing, but payload integration, checkout and post-launch data and analysis as well. The imaging and data analysis software developed during breadboard testing is incorporated directly into these other program phases.

An experimental Fairchild CCD-211 was placed in the 2.1 m coude spectrograph at the Kitt Peak National Observatory and used to record an 87 Å spectral band centered on Hα. On the night of 1979 July 11 UT date, this system was used to observe continuously the extreme 8 Cephei variable BW Vulpeculae throughout one of its 4^h49^m cycles with an average exposure of 13 minutes per observation. A total of 18 observations was secured. The results show dramatic profile variations of Hα, including features not previously reported, and extreme variations of the C II λλ6578, 6582 lines, including variations of equivalent width. The fast time resolution capability and the photometric linearity of the CCD has permitted the detection of subtle effects which have been missed by photographic observations, and has led directly to important new interpretations of the complex atmospheric pulsations in this star.

A CCD camera for use in astronomy based on the use of RCA SID 53601 is described. The CCD format is 512x320 with 30 μ pixels. The camera has been onerated at the 1.5m and 0.4m telescopes at Mount Hopkins.

We describe a new instrument and data handling scheme which will automatically carry out a photometric survey for variable objects to a limiting magnitude of about 20, and a polarimetric survey for objects which are 1% or more polarized, to a limiting magnitude of about 18. The instrument consists of a dedicated 0.76m, f/4.7 Newtonian reflector which is used as a transit telescope, and two area-format CCDs which are placed in the focal plane and clocked at the sidereal rate. An effective integration time on a point on the sky of about one minute is achieved by this technique. We discuss the photometric advantages of "averaging over" all spatially dependent noise sources when CCDs are used in this way. The system noise and dynamic range of the instrument are discussed assuming the use of RCA thinned, buried-channel CCDs. Two astronomical projects, the definition of a homogeneous, unbiased, sample of QSOs, statistically complete to about 20th mag, and the discovery of supernova outbursts on the rising branch of the light curve, are described. A list-oriented real-time data compaction scheme is proposed to allow easy management of the vast amount of data generated by this instrument.

A four-stage electrostatic image intensifier transfer lens coupled to a plumbicon television camera is used both as a photoelectron event-detecting system and as an analogue detector for the Steward speckle camera. The system is capable of continuous logging of photoelectron event data allowing 100 percent utilization of telescope aperture time by use of a Grinnell GMR-27 video digitizer and graphic television display with a special modification for lag-free event detection. Data can be processed on-line at the site or recorded for off-line processing using a standard analogue video recorder. A seeing-corrected reconstruction of the diffraction limited image derived from the speckle interferometric image autocorrelation computed from 200 television frames of the magnified image of a seventh magnitude close visual binary star observed with the Steward 2.3 meter telescope is reported. The system has been applied to speckle interferometry of objects as faint as visual magnitude 16.

The MASCOT (MIT Astronomical Spectrometer/Camera for Optical Telescopes) is an instrument capable of simultaneously performing both direct imaging and spectrometry of faint objects. The optical design is dictated by the characteristics of the charge coupled device (CCD) detectors and the observational requirements for the instrument. The mechanical configuration of the instrument allows maximum flexibility in the choice of angular scales for the imager and resolution for the spectrometer. The sensitivity of the device is limited by the sky brightness, the overall quantum efficiency, the resolution, and the readout noise of the CCD. This is the first of two papers describing the MASCOT.

The data collection system for the MASCOT (MIT Astronomical Spectrometer/ Camera for Optical Telescopes) is described. The system relies on an RCA 1802 microprocessor-based controller, which serves to collect and format data, to present data to a scan converter, and to operate a device communication bus. A NOVA minicomputer is used to record and recall frame images and to perform refined image processing. The RCA 1802 also provides instrument mode control for the MASCOT. Commands are issued using STOIC, a FORTH-like language. Sufficient flexibility has been provided so that a variety of CCDs can be accomodated. At present, Texas Instruments virtual phase CCDs are utilized. This is the second of two papers describing the MASCOT.

A package of programs is presented which is devoted to automatic processing of astronomical images,with special reference to the analysis of clusters of galaxies. Problems involved in processing large-size images (e.g. 4000x4000 pixels or more), containing a very large number of objects (several thousands), are such that interactive processing is not practicable and algorithms for automatic threatement must be developed. The package described has a structure centered on two data sets: the 'image data-file' and the 'catalogue'. Details in data organization and handling are exposed together with the I/O management which was adopted. The main automatic processing algorithms are then exposed and some example of threatement are presented. Astronomical results obtained using this software are described in another paper from this same Congress.

The interactive Astronomical Data Analysis Facility, IADAF, of the Laboratory for Astronomy and Solar Physics is designed, implemented and in the process of doing the interactive analysis of the astronomical data obtained by the Laboratory scientists. The facilities include a Grant measuring engine, a PDS 1010A Microdensitometer, a COMTAL, image display system, and a PDP 11/40 computer system. This paper will present the hardware and software tools that are currently available for the analysis of astronomical images.

The angular resolution of conventional astrophotography is limited to about 1 arc second due to image degradation caused by the turbulent atmosphere of the earth. Higher resolution can be obtained by Labeyrie's stellar speckle interferometry . Stellar speckle interferometry yields the autocorrelation of the object intensity distribution with diffraction-limited resolution, for example a resolution of 0.03 arc second in the case of a 3.6m telescope. We will report the following applications of digital and optical-digital stellar speckle interferometry: (a) measurements of close binary stars (b) dependence of the signal-to-noise ratio of the reconstructed autocorrelation on the exposure time of the speckle interferograms and on the number of processed speckle interferograms, and (c) measurement of the red giant Omicron Ceti.

For over two years the European Southern Observatory has provided an image processing service for its staff and for visiting astronomers. It is in the process of updating both the hardware and the software that support this service. We present some details of the philosophy behind this service and some of the important lessons we have learned. We discuss various aspects of the astronomical image processing service concept.

The Starlink 'Software Environment' will provide a command language enabling the astronomer at an interactive terminal to manipulate data by specifying operations in a concise but natural way. It will also define a set of subroutine interfaces which will give the applications programmer access to command parameters, images and other bulk data, graphics devices and other peripherals. The paper discusses the philosophy of the software environment and gives details of the program interface.

Using the Tololo-Vienna Interactive Image Processing System as an example, it is demonstrated how software and systems can be interchanged between different computers. Transportability and compatibility criteria are given. The capabilities of the system are summarized. The system source (in DEC FLX-DOS format on 9-track 800 bpi magtape) as well as the necessary documentation is available on request from the author.

The Jet Propulsion Laboratory's Scientific Data Analysis System will process Infrared Astronomical Satellite data and produce a catalog of perhaps a million infrared sources in the sky, as well as other vital information for astronomical research.

A recursive algorithm is described which detects and characterizes point sources and extended sources in the data obtained from the Infrared Astronomical Satellite (IRAS) in the presence of non-stationary noise. The analysis of tests using simulated data indicates that the performance of the point source detector is very close to that expected from a matched filter with stationary gaussian noise. The false alarm rate of the extended source detector tends to be higher than expected at a given SNR.

The IRAS telescope instrument will survey the entire infrared sky in four wavelength bands over a period of one year. Although this device is inherently non-imaging, various calibrated and geometrically controlled imaging products are created, suitable for qualitative and quantitative scientific interpretation. The Image Processing Laboratory of the Jet Propulsion Laboratory was responsible for the design, development and application of the software required to produce these imaging products.

A facility capable of automatically selecting guide stars for Space Telescope is described, which, as presently envisioned, consists of two microprocessor-controlled high speed microdensitometers, a central processing computer, an extensive plate library, and a large, continually evolving data base, all to reside at the Space Telescope Science Institute.

The Faint Object Camera is the ESA instrument to be flown in the Space Telescope. This paper describes the main characteristics of the instrument, its scientific capabilities, and the software required to analyze the data that it produces.

Examination of biological structures at the level of whole cells presents several major problems that can be solved using two- and three-dimensional reconstruction and image enhancement techniques. Presented here are first steps towards realizing this goal of cellular tomography. General methodologies for extraction of additional information from biological objects using median and bandpass filtration and constrained deconvolution procedures are described. These image processing techniques are ideally suited for studying large non-crystalline objects by either optical or electron microscopy. The ultrastructural architecture of Drosophila sperm heads has been investigated, revealing that these examples of highly-condensed DNA have a defined arrangement based on helical principles.

The large amount of artifacts on electronographic plates has to be removed automatically using fast digital filters. A group of one-dimensional non-linear recursive filters based on zero and first order estimates of the expected pixel value is investigated. Modifications are made when the difference between the pixel value and the estimate is larger than a given limit. A satisfactory performance can be achieved using a variable limit which depends on the estimate value and gradient. A comparison between these filters and a non-recursive median filter shows that the former is more efficient because a smaller size can be used.

Three kinds of artifacts unique to digital images are illustrated: aliasing caused by undersampling; interference phenomena caused by improper display of images; and harmonic overtones caused by quantization of amplitudes. Especial attention is given to undersampling when the sample size and interval is the same. This situation is important because it is typical of solid-state cameras.

The passage of cosmic ray secondaries through unthinned CCD detectors may produce numerous spurious images in moderate-length astronomical exposures min). The intensity of these cosmic ray tracks is usually greater than that of most of the features of interest. In the present paper we investigate the relative merits of several techniques for removing these artifacts from multiple CCD exposures of the same scene. We first investigate various single-point outlier rejectia criteria, and then go on to study techniques that make use of the spatial distribution of actual cosmic ray tracks. Applications of these techniques to typical astronomical CCD exposures are given.

The general considerations for a survey instrument are discussed. The infrared telescopes used by AFGL for the sky survey are ac coupled to minimize dynamic range requirements, scan and 1/f noise. However, this high pass filtering also attenuates signals from extended celestial sources. The process by which the effects of this filtering may be deconvolved from the data is briefly described. The problem at this stage is the familiar one of separating unwanted background and noise from the signal of interest. Reasonable separation of the the extraneous signal variations from the higher frequency signal of interest was obtained by sequentially smoothing the data in two coordinates over an interval of about one degree with a non-linear filter. A low resolution map which clearly shows large scale diffuse emission is a direct result of this smoothing. It was found possible to improve the resolution of the mapping with further processing to as high as the uncertainties associated with detector size and uniformity will allow.

The first nonlinear image restoration algorithms were devised a little more than a decade ago. The subsequent development of this subject by a number of research workers has produced a rich and fascinating literature. But because much of it is located in unfamiliar journals and publications, many astronomical newcomers to the field may be unaware of this work. It has been known since the discovery of the nonlinear image restoration techniques that they have pronounced performance advantages over linear restoration techniques in astronomical applications, and many of the published examples of nonlinear restorations of imagery have involved astronomical data. The new image detector systems appearing in optical astronomy, particularly CCDs, produce images of a quality that fully justifies the employment of sophisticated algorithms for the extraction of the maximum amount of information from the data. This review of the literature has been prepared in the hope that it will encourage new astronomical workers to enter into it.

A technique is described for mathematically extracting information regarding the radiation characteristics of the constituents of an optically unresolvable composite radiation source made up of a finite number of individual radiators. The radiation characteristics of the individual sources are assumed to be known. This method requires multispectral band measurements of the composite signatures. The algorithm determines the number of each kind of radiator contributing to the signature. The number and types of radiators chosen as models must represent the range of radiators that can be expected to be present in the composite source. This method has been implemented on a computer and has been applied to the analysis of a computer-simulated galaxy in terms of its stellar population and to the analysis of a simulated multiple star system in terms of the number and kinds of stars present. The theoretical basis of this technique is outlined and the results of numerical experiments discussed. The effects of corrupting the signature with white noise to simulate random measurement errors are also discussed.

We have carried out photometry of stellar images from plates taken with a Kron electrographic camera and measured with a PDS 1010 microdensitometer. Attention has been given to significant sources of error in measurement and reduction of the stellar images and in photometric calibrations of the electrographic camera. These include: sky background noise crowding plate defects detector areal response color transformations linearity mjcrodensitometer errors. Each has been investigated in isolation in order to minimize its contribution to the photometric uncertainty of a stellar measure. As in conventional photoelectric photometry some sources of error are difficult to reduce below the one percent level. For well exposed stellar images the photometric uncertainty deduced from comparisons with photoelectric calibrations is less than 3 percent for a single measure. Although the techniques described were developed using electrographic camera plates measured on a PDS microdensitometer, the general principles are applicable to photometry with any type of panoramic detector.

Software available at KPNO for performing stellar photometry on digital images is summarized. Aperture sum and two dimensional fitting techniques are described and compared in terms of accuracy, versatility, and computational efficiency. Algorithms are presented for deriving the point spread function (PSF) from intensity data, and fitting it via chisquare minimization techniques to either single or multiple stellar images. The results of tests performed on artificial starfields are summarized and evaluated. Two dimensional psf fitting techniques are seen to be a versatile and accurate tool even in fairly crowded fields, though computationally quite expensive compared to aperture sum techniques.

Results concerning the U, B and V photometry of some galaxies in the cluster Zw 1305.4+ 2941 are presented. The cluster has a redshift of 0.24 and the photometry is referred to galaxies which are inside a region of radius 1.2 Mpc from the cluster center. To obtain these resutis an automated reduction procedure was applied to the microdensitometer data obtained scanning a region of Palomar 48" plates. These procedures include : a) a segmentation process, b) a smoothing, ca calibration of the plates using standard stars profiles and magnitudes, d) star-galaxy classification.

The Princeton PDS microdensitometer has been used in a novel manner to automatically blink plates. The plates are photometrically calibrated using the known brightness profile of certain galaxies in the field to provide the density-brightness relation for the plates. All objects present on the plate are catalogued. This procedure is repeated for another plate and the catalogues for the two plates are compared to determine objects which have changed significantly in luminosity between the plates. These objects are then checked visually to eliminate the effects of plate flaws and to determine if the luminosity change is the result of a physical change in the object. This technique has been used to search for supernovae in clusters of galaxies, particularly Coma. No supernovae have yet been detected but the objective nature of the search technique permits the calculation of well-defined upper limits on the supernovae rate.

A set of schemes for locating objects of interest (color, variability, morphological form, etc.) by automated search of photographic plates is described. These techniques are designed to allow rapid and efficient processing of large areas of plate and to make minimal demands on the homogeneity and calibration of the plate material. They are based in part on the techniques of nonparametric statistics. Projects using these methods which are currently being carried out with the Princeton PDS microdensitometer and image processing system are also briefly described.

A simple method for the detection of quasar-like or unusual objects by computer is described using the output produced by the COSMOS measuring machine. One method of finding quasars in quantity is to search objective prism plates by eye. However, while this method is successful, it does have some serious shortcomings. 1) The timescale for measuring a single plate from the United Kingdom Schmidt Telescope (UKST) survey by an experienced observer is of the order of one month. A second observer then goes through the plate again in order to reduce the number of missed objects. 2) Given these timescales, it is difficult to do many plates. 3) The plates have to be of the very highest quality. A small increase in the seeing and the numbers of objects detected drops sharply. 4) The sky distribution when measured in this way may reflect observer fatigue etc. in subtle ways. It occured to me at the Schmidt Conference in Cambridge held in December 1979 while listening to Cyril Hazard that it might be possible to classify objects on prism plates directly using COSMOS with simple parameters as had already been done by MacGillivray et all for star/galaxy seperation. Several parameters have been tried so far and it is clear that some parameters will detect some quasars and a different set of parameters other quasars. So far, no single parameter has been found to detect all quasars. One simple parameter that does seem to give a good chance of success is the ratio of the weighted semi-major axis to the semi-minor axis. These are merely two of the 18 parameters given out in the current version of COSMOS. (see the paper by Dr. R. Stobie this conference). Briefly, COSMOS produces output of a field in such a form that the ellipses around an image can be drawn using the second moments. All clean images have ellipses pointing in the Y direction. Large or contaminated images produce either circular images or orientations away from 90°. These are removed from the sample. The plot of COSMOS "magnitude" against axial ratio can be done. The points to the right of the graph and to the faint end are either artifacts caused by merged images or genuine images with a U-V excess for their magnitude. The selection of this subsample is done by computer program and an accurate overlay drawn. The skilled observer can then decide on which images merit further study. In order to give an impression of the scale of the problem for the visual observer, COSMOS detected over 75000 images in the unvignetted part of U.K.S.T. plate 2460. (RA 22^h Dec-18.55). The final overlay represents a mere 1% of this total . Just how many of these objects are really QSO's (and I would not believe more than 20% were) is questionable until a full comparison is done with archive data and proper telescope observations made. At this stage I can only confirm that some of the selections are undoubted quasars . Given that 1500 quasars are already known, it is a fair and proper question to ask why we should be looking for a lot more. I would argue that there are many questions that cannot be answered by such a small sample. It only represents 2½% of the total UKST survey. One final detail, you can turn the algorithms around to look for circular objects on prism plates. These will be either very red objects, emission line only objects or very unusual things indeed (Kodak plate flaws are regretably included in this list). The difference is though, that these kinds of unusual objects go down to the limit of the direct Survey plates.

We present a digitized Stellar Photometry Automated (SPA) system capable of treating large amounts of information with little intervention from the astronomer. SPA automatically finds stellar objects, performs a cross correlation of all centers in all plates and applies an algorithm to derive a magnitude. Different magnitude algorithms are used such as analytical and numerical integration of the individual stellar arrays. Because of the linearization and the background-subtraction capability the results are of better quality then in conventional analogical techniques i.e. iris photometry, and can be moderately extrapolated. Data selection can be performed with the aid of a quality index. Techniques used in SPA are graphically illustrated and applications as well as future developments are briefly described.

Panoramic astronomical photographs may contain information on up to one million images of stars and galaxies. To extract this information in a day requires a high-speed measuring machine and image analysis system. Each stellar or galaxian image may be regarded as a connected set of pixels above some local threshold. The moments (unit-weighted and intensity-weighted) up to second order of the pixel distribution for each image are calculated and form the basis of a set of image parameters. This type of analysis is suitable for the great majority of images which do not show complex structure intrinsic to the source. These moments provide data in three basic categories of information relevant to the astronomer, i.e., astrometric, photometric and image classification. Application of this scheme and the accuracy of the image parameters is demonstrated with data obtained from the COSMOS measuring machine.

A system for detecting and classifying faint objects on astronomical digital Pictures is described. Algorithm and implementation considerations are given, and its performance is evaluated. The optimal "phi" classifier (briefly described) is used to separate stars from galaxies. The major emphasis is on speed. A 512 by 1536 pixel picture can be scanned and fully processed in about 5 minutes total time on a PDP 11/34 minicomputer. On plates taken with the Palomar 1.2 m Schmidt telescope, stars can be reliably separated from galaxies down to a limiting red magnitude of 19.6. Objects down to about 21st magnitude in red light can be detected. This system is part of a larger system which includes a highly modified David W. Mann two-dimensional scanning microdensitometer for image acquisition, and an extensive image processing system, all operating under compatible formats and conventions.

A system, FOCAS (Faint Object Classification and Analysis System), designed to automatically detect and catalog stellar and galactic images on photographic plates is described. FOCAS was designed and is used to find all objects brighter than a limiting magnitude (24th on nitrogen baked IIIaJ plates exposed for one hour on the KPNO 4m telescope) and classify each image as stellar (nonresolved) or galactic (resolved). An important task in the implementation of this system is to verify that it performs as designed and to establish its limitations. The following internal tests were made to establish confidence in the automated cataloging system. Processing and comparing objects from two plates of the same field yields information about object detection efficiency and classification consistency. Processing synthesized dim stellar images provides detection efficiency information. Classification of synthesized stellar and galactic images gives information regarding classification accuracy. Processing a uniformly fogged plate establishes the magnitude where emulsion irregularities begin being detected as images. Comparison of FOCAS results with deeper CCD and video camera images corroborates these internal tests.

This paper presents results on spectral line and profile variability, equivalent widths and line identification for α Cygni (A2 Ia) and ε Aurigae (A8 Ia). The results are based upon photometrically precise spectra obtained with a Michelson-Fourier spectrophotometer. The wavelength interval extends from 0.48 to 1.02 microns, approximately. The spectral resolution is 3.85 cm^-1. The analysis has been carried out totally with computers using, both, automatic and interactive techniques. These are briefly discussed.

We studied three types of faint emission features associated with solar flares -- moving emission fronts, flare halos and Moreton waves. They are all diffuse, rapidly moving phenomena that have classically been studied using solar movies, because their motion renders them more readily apparent to the eye. We searched for an easier and more quantitative method of analyzing these phenomena using still prints. Using the facilities of JPL's Image Processing Laboratory we applied various VICAR algorithms to eight selected events. The techniques employed include contrast enhancement, isointensity contouring, differencing of images, spatial filtering and geometrical registration. We have studied the spatial extent and temporal behavior of the phenomena, the connection between the three different types of phenomena, the possible relation to white-light coronal transients and different physical models for these features.

We describe an ongoing effort to superimpose x-ray, optical and radio imagery of supernova remnants. The major steps in resampling the data onto a common celestial grid are outlined and initial results are presented for the Cygnus Loop.

Ellipticity and twisting of the isophotes of four lenticular and seven elliptical galaxies in the Virgo cluster are presented as a sample of a more complete photometric investigation. This work has been motivated by the increasing importance of this kind of information for the understanding of the spatial structure of E galaxies. The calibrated plate material from the Loiano 1.52 meter and Tautenburg Schmidt telescopes has been digitized with a PDS microdensitometer and analysed by means of the Interactive Numerical Mapping Package (IMP). Ellipticity and orientation profiles are presented in a graphical form together with a preliminary discussion. A correlation has been found between ellipticity and twisting in barred lenticulars which might help in the understanding of some E galaxies such as NGC 4406 and NGC 4374. Twisting has been detected in all of the seven ellipticals of the sample.

Low dispersion spectra extending over the wavelength range λλ1150-3250Å have been obtained with the International Ultraviolet Explorer (IUE) satellite at 35 neighboring locations defining a mosaic within the central region of the Orion Nebula. These spectra have been processed in a unique way to assemble monochromatic images of the emission in the wavelengths of the most prominent ultraviolet (UV) spectral lines seen in the nebula: CIII] λ1909, CII] λ2326, and [OII] λ2470. The mosaic images, covering approximately a 0.6 arcminute by 2 arcminute region including part of the bright bar, have a spectral resolution of ≈6Å and a spatial resolution of ≈4-5 arcseconds. The image processing techniques used to extract each 2 arcsecond-by-2 arcsecond picture element of the mosaics from the original IUE spectra are discussed. These procedures include calculation of spectrograph orientation and thermal effects, normalization for exposure time, subtraction of background, correction for sensitivity variation within the 10 arcsecond-by 20 arcsecond IUE spectrograph aperture, correction to an absolute flux scale, sample interpolation, and display on graphic devices. The resulting UV emission line intensity maps may be used in conjunction with observations of comparable resolution in other wavelength regions to infer the spatial distribution of ionization and abundance levels of carbon and oxygen in Orion.

TAURUS is a new Fabry-Perot imaging device, designed to obtain complete, seeing-limited radial velocity field maps of extended line sources. In this paper we describe the data handling and reduction processes necessitated by the large 3 dimensional data arrays created by the device.

Monochromatic images of three planetary nebulae, NGC 6720, NGC 7662 and HOC 2392, were taken using narrow band interference filters centered on the forbidden emission lines of Oxygen I, II, III, Nitrogen II, Sulfur II and the permitted emission lines of Hydrogen I, Helium I and Helium II. The data was taken with a silicon intensified vidicon using the Palomar 1.5 meter telescope and was recorded digitally to an encoding level of 12 bits. The data was processed at the Image Processing Laboratory of the Jet Propulsion Laboratory. The calibrated images were used to investigate the three dimensional structure of the nebulae and to generate two-dimensional electron and temperature maps.

Trying to determine the size of galaxies and looking for tails and connections between galaxies can be intriguing. These very faint features are often buried in the film grain noise. Our study is of the NGC 3623, NGC 3627 and NGC 3628 region. The search for these faint features is complicated by film variation, sky background, microdensitometer drift and stars in the neighborhood of the galaxies. We address these questions and show that faint features can be found with the use of judicious data stretching and averaging along suspected features.

Image processing techniques employed in both the acquisition and analysis of UBV surface photometry of galaxies are described. Results are presented in the form of greyscale coded maps for the barred galaxies NGC 4314, NGC 6181, and NGC 7479.

Digital image processing of spiral galaxies may be Performed for a variety of purposes: instrumental calibration and geometric correction, cosmetic processing, and analysis of specific scientific questions. This paper will discuss only the latter. The purpose is to illustrate a particular analysis procedure and to discuss the hardware and software required to facilitate the ever changing needs of the astronomer performing this type of investigation. The specific illustration is the analysis of stellar populations in M83 by use of UBV photographic images.

The basic FITS format for the interchange of digital array data was first described in 1979 and is now in use by a wide variety of astronomical institutions. Since the original format was inefficient for use with groups of small arrays, we have now proposed an extension to FITS which supports "arrays" which are irregularly gridded in one or more of the coordinate axes. These formats provide a simple but powerful mechanism for the unambiguous transmission not only of binary image data but also of a virtually unlimited number of auxiliary parameters that may be associated with the data.