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An analysis technique for biological shape based on the concept of bending energy has been developed. The technique permits the calculation of the amount of energy (work) that would have to be expended to form typical biological shapes out of a linear, thin-shelled medium. In addition the development of this analysis procedure provides several new results concerning image processing including a sampling theorem for simply connected closed contours and a fast algorithm for calculation of the bending energy.

A procedure is developed to extract numerical features which characterize the pore structure of reservoir rocks. The procedure is based on a set of descriptors which give a statistical description of porous media. These features are evaluated from digitized photomicrographs of reservoir rocks and they characterize the rock grain structure in term of (1) the linear dependency of grey tones in the photomicrograph image, (2) the degree of "homogeneity" of the image and (3) the angular variations of the image grey tone dependencies. On the basis of these textural features, a simple identification rule using piecewise linear discriminant functions is developed for categorizing the photomicrograph images. The procedure was applied to a set of 243 distinct images comprising 6 distinct rock categories. The coefficients of the discriminant functions were obtained using 143 training samples. The remaining (100) samples were then processed, each sample being assigned to one of 6 possible sandstone categories. Eighty-nine per cent of the test samples were correctly identified.

In image processing of aerial photographs in cartography and of remote sensor data in earth resource surveys, one of the most basic parameters is the elevation of the ground estimated by means of parallax measurements made on stereo pairs of aerial images. In conventional methods, measurement by manual stereocomparators is precise but timeconsuming. Existing automatic stereocomparators do not work well because they use too simple a correlation method to get sufficiently precise measurements. Each of the two corresponding patterns from a stereo pair is so distorted by parallax that the calculated correlation value does not always attain the maximum at the point from which we can obtain the correct parallax. As a result of the present study, it appears that an iterative prediction and correction method can be suitable for the efficient and accurate measurement of elevation from stereo imagery. The conventional methods do not fully utilize the information which is presented in the image itself or is a priori known. The first prediction of elevation is carried out only for well-contrasting parts of the image, which usually means roads, coast, forest edges, etc. Then this prediction is expanded to the neighboring parts, making use of the continuity of elevation. Using a temporary predicted elevation map, one of the stereo pair patterns is modified to lessen the distortion compared with the other pattern. Correction of the elevation map is performed using the correlation values calculated from the modified patterns. This feedback procedure is iterated until no correction is needed. This new method is applied to digitized aerial photographs taken at a height of 3,000 m. Finally, a planned automatic image processing system is explained briefly, consisting of a newly developed scanner which can access every point in a scan field at high positional accuracy.

EG&G, Inc., a leader in the field of photographie data acquisition and analysis for over 25 years, has for the past five years been placing increased emphasis on digital image processing in support of the Field Testing Division of the Los Alamos Scientific Laboratory under AEC Contract No. AT(29–1)1183. During that time, capabilities that originally involved photogrammetric and radiometrie analysis have been augmented to include two-dimensional Fourier frequency analysis and spatial filtering of images. This article describes some of the image processing equipment at EG&G, along with the results obtained using this equipment, and discusses digital holography in greater detail.

A model for image processing proposed earlier is discussed and applied to some optical illusions. A simulation on a computer is provided in an attempt to reach a quantitative level of understanding in the study of visual phenomena.

An approach to image processing is made by means of image scanning with an aperture array. The restoration of one-dimensional linear blur is taken as an example, and methods of designing the aperture array and evaluating its performance are discussed. The quality criterion of restored images with regard to resolution and detection is introduced and applied to the practical system.

The spatial and spectral luminance properties of a cloud's surface are being studied to gather more information about the microphysical processes occurring within the cloud. A real-time, field-implementable image processing system has been developed by the authors to sense and display this luminance information, and is described in this paper. Applications, including the investigation of “crown flash” phenomena, are described.

Digital filtering of images is considered. A recursive filter design for two-dimensional separable filters is discussed which is based on state variable methods. Advantages of this design are guaranteed stability, and shorter word length than filters designed by bilinear mapping techniques, greater computational efficiency and easier design as compared with nonrecursive filters. Results are shown for filtering high frequency additive noise from a low spatial frequency image and for filtering a low frequency multiplicative noise from a high spatial frequency image.

The state of the art in large-scale digital computers has recently opened the way for high resolution image processing by digital techniques. With the increasing availability of digital image input/output devices it is becoming quite feasible for the average computing facility to embark upon high-quality image restoration and enhancement. The motivation for such processes becomes self evident when one realizes the tremendous emphasis man puts on his visual senses for survival. Considering the relative success achieved in one-dimensional (usually time) signal processing, it is to be expected that far greater strides could be made in the visual two-dimensional realm of signal processing.

This paper describes the fabrication and demonstration of a real-time incoherent-to-coherent optical converter having applications in image processing systems. Briefly, it utilizes the photoconductivity effect in the single-crystalline electrooptic material, Bi 12 SiO 20 to spatially modulate its electrical polarization. An optically absorbed write-in image is stored as an image wise polarization pattern in the device. Readout is accomplished electrooptically by means of the subsequent phase retardation that a polarized beam of coherent light undergoes in passing through the Bi 12 SiO 20 . An operating mode for achieving continuous image conversion with high-speed recyclability is described. The following performance characteristics have been demonstrated : write-in intensity of 300 µW/cm2at 400 nm yielded a contrast ratio of 50:1 after 40-ms exposure. When the converter was operated at a frame rate of 10/s, a sampled read-out contrast ratio of greater than 1000:1 was achieved. Resolution in excess of 80 1p/mm has been recorded and read out. The crystal growing and device fabrication methods by which 1-square-in converters have been built and operated are described. Results achieved in using this device to Fourier transform images are also presented.

A method for the determination of lightness from image intensity is presented. For certain classes of images, lightness corresponds to reflectance, while image intensity is the product of reflectance and illumination intensity. The method is two-dimensional and depends on the different spatial distribution of these two components of image intensity. Such a lightness-judging process is required for Land's retinex theory of color vision, A number of physical models are developed and computer simulation of the process is demonstrated. This work should be of interest to designers of image processing hardward, cognitive psychologists dealing with the human visual system and neurophysiologists concerned with the function of structures in the primate retina.

In recent years there has been an increasing interest in the processing of pictorial images by digital computer. Since the initial success of digital image correction at JPL in support of the space program, considerable effort has been devoted to applying image processing techniques in a wide variety of application areas. This effort has involved the direct spin-off of some basic research results in industrial applications and the utilization of this experience in establishing relevant directions of new image processing research and development.

An interactive computer environment is one which attempts to facilitate the interplay between man and machine in pursuit of a goal defined by man. Presumably, to be effective, this environment should allow the calculating speed, precision, and structured logical/iterative skill of the machine to serve the conceptual, intuitive, highly associative, and contexturally sensitive attributes of human mental function in the solution of problems. Too often the match is obtuse, the goals vague, and the result frustration. Much emphasis ought to be placed on the a priori specific problem oriented knowledge, gained through experience, which the man brings to the machine and wishes to share with it in a versatile but structured way.

Rat liver histological sections were photographed through a Leitz microscope and the negative digitised using a P-1000 Photoscan micro-densitometer (OPTRONICS). In the system the transmitted light through the film was measured using a photo-detector, converted to 256 grey levels, and stored on a 7 track magnetic tape. The optical density was measured every 100 microns. The final picture consisted of 750,000 points. These were fed into a PDP-15/40 computer with core requirements of 24 K words and two 250 K word disks, and analysed. The present paper describes a detailed analysis of one heptocyte.

A brief review of recent advances in the quantitative capabilities of the scanning electron microscope is presented. Special emphasis is placed on scanning transmission electron microscopy, X-ray techniques, secondary ion mass analysis, selected area electron channeling patterns, and image processing techniques. A systems approach to the development of the SEM as a research tool is recommended.

The application of digital image processing techniques to medical problems has been under development at the Jet Propulsion Laboratory, California Institute of Technology, since 1966. The initial research concentrated on medical X-ray films and include (1) image restoration, i.e., using digital techniques to retrieve information partially lost in the imaging system which generated the pictures, (2) image enhancement to emphasize features or remove useless data, and (3) image mensuration to provide more quantitative measurements and analyses than are available through visual inspection techniques. From the initial concern with X-ray image processing, this research in image processing as applied to biomedicine has been expanded to include a system for the automated analysis of images from light and electron microscopes. The Automated Light Microscope System (ALMS), around which the chromosome analysis system has been developed, allows direct scanning of specimen images into a computer for subsequent analysis. The applications of digital image processing to biomedicine at the Jet Propulsion Laboratory encompass 15 separate research projects. The areas selected for discussion in this paper give some indication of the types of picture analysis that are being performed. The current trend in biomedical image processing is toward more human interaction in the research setting.

After an overview of the cellular logic image processor, CLIP 3, parallel algorithms for joining two points are described. These real time algorithms are simple, work properly, preserve the connectivity, are based only on logic, and show much of the behavior of processing occurring in sensory elements of animals.

This paper describes an algorithm for the approximate solution of vector Toeplitz systems via an iterative-improvement method. The algorithm exploits the special structure of Toeplitz matrices, namely, their similarity to vector circulants, and is particularly well suited for solving large systems. Sufficient convergence conditions and concrete error bounds for the iteration are presented along with an application of the routine to a problem in the design of planar digital filters for image processing.

Recursive restoration of two-dimensional noisy images gives dimensionality problems leading to large storage and computation time requirements on a digital computer. This paper shows a two-dimensional second-order Markov process representation can be used for fast recursive restoration of images with small storage requirements. Advantages of this method over existing techniques are illustrated by means of examples.

A preliminary implementation is described of a new language, IMPROC, for performing many of the “routine” but complicated tasks of image processing in the electron microscopical context. The implementation is based on a library of precompiled routines written in a high level language, suitable calls being generated by a macropro-cessor operating on the IMPROC statements. The technique is particularly easy to transfer from one computer to another, and could be used to develop specialized languages in other fields.

The main zones of seismic energy release in South Australia probably correspond to major basement fractures. A method is given here to extract the energy release trends from seismicity maps, in order to outline subsurface lineaments more accurately. The techniques are similar to those employed in image processing. Tectonic structure may be revealed which is not readily apparent from epicenter plots or other geophysical data.

This paper describes various forms of line drawing representation, compares different schemes of quantization, and reviews the manner in which a line drawing can be extracted from a tracing or a photographic image. The subjective aspects of a line drawing are examined. Different encoding schemes are compared, with emphasis on the so-called chain code which is convenient for highly irregular line drawings. The properties of chain-coded line drawings are derived, and algorithms are developed for analyzing line drawings to determine various geometric features. Procedures are described for rotating, expanding, and smoothing line structures, and for establishing the degree of similarity between two contours by a correlation technique. Three applications are described in detail: automatic assembly of jigsaw puzzles, map matching, and optimum two-dimensional template layout

An extension to the basic concept of correlation detection as a means of image registration is developed. The technique involves linear spatial preprocessing of the inages to be registered prior to the application of a correlation measure. This preprocessing operation utilizes the spatial correlation within each image and greatly improves the detectability of image misregistration. An analysis of the computational aspects of the algorithm is given. Also, results of a computer simulation to evaluate the technique are given.

Research in digital image processing at The Aerospace Corporation has been concerned primarily with the exploration of techniques for use in both civilian and military areas. In particular the research has centered on applications in law enforcement, earth resource assessment, and military systems design. Recent interests have also been extended to restoration of photography of space objects. While the central theme of the research has been dedicated to solving engineering problems, much effort has been expended in the development of general techniques and software to complement the applications studies.

放射性同位元素 (ラジオアイソトープ) を投与して, それがヒトの臓器に集積した時点で外部よりイメージ装置によって撮影する像をシンチグラムと呼び, 核医学における重要な診断技術となっている.この像を電子計算機によってディジタル的に収録し, 画質の改良と表示, 空間および時間領域での特徴抽出の方法が研究されている.

The intensity point spread functions and the optical transfer functions for focussed and defocussed optical systems with slit shaped rectangular apertures are given. Focussed and defocussed systems with point spread functions of similar size are compared. An application to the incoherent processing of geological data is described.

Nearly everyone has seen the pictures brought back from the moon by the U. S. astronauts. Less remembered nowadays are the television pictures sent back from the moon's surface by the early unmanned lunar vehicles; these pictures were equally spectacular in their time and perhaps more important, since they gave NASA the basis on which to make the judgements about lunar terrain pertinent to the landing of a manned vehicle. Many people remarked on the sharpness and clarity of the television pictures of the moon, and similar ones now coming from Mars. But to the digital image processing community, the quality of the lunar images was no surprise, and was recognized as a result of the work done at NASA's Jet Propulsion Laboratory. JPL had digitally enhanced the incoming television images, imparting to the images sharpness that was sometimes missing in the originals.

A number of signal processing techniques which have been developed for processing one-dimensional sequences do not generalize to the processing of two-dimensional signals, largely due to the absence of a two-dimensional factorization theorem. In an attempt to circumvent this problem, a specific representation of two-dimensional sequences as one-dimensional sequences is presented in this paper. Using this mapping several two-dimensional problems can be viewed as one-dimensional problems and approached using one-dimensional techniques. This representation is valid both for signals of finite extent and for the more general class of signals with rational Z-transforms. In this paper we consider applications of these techniques for high speed convolution, processing of drum scans, and two-dimensional finite impulse response (FIR) filter design.

Heuristic methods of-prel iminary image processing used some position-invariant operators [ I ] [ 3 ] . This term was used to denote operators on images, which are permutable with any image-transfer operation in the field of view. Thus, in order to isolate a contour one makes use either of a discrete analog of the Laplace operator or of the gradient modulus; for smoothing purposes one uses the operator consisting of averaging over a vicinity.

In the formation of an optical image, each surface element of the object gives rise to a more or less blurred distribution in the image surface, of total brightness proportional to that of the object element. The image is the sum of these distributions in the appropriate sense: when the object is coherently lit, the image is built up by adding their complex amplitudes; when the object elements are regarded as incoherent it is the intensities which are added. In both cases the image can be expressed as the convolution of the object with a spread function which characterizes the optical system. In systems for which the spread function does not change appreciably from one part of the field to another, the Fourier transform of the image is obtained to a sufficient approximation on multiplying the Fourier transform of the object with that of the spread function. More generally, this holds for any part of the field of a non-isoplanatic system over which the changes in the form of the spread function are small enough to be disregarded; we call such an area an 'isoplanatism-patch'. Working over such an area, an optical system can be regarded as a linear filter in which the Fourier components of the object reappear in the image multiplied by 'transmission factors'. These factors, first considered by Duffieux, depend on the aperture and aberrations of the system, and in Section 2 they are evaluated in terms of an ikonal function. The qualities required of an optical image are so varied that an assessment valid over the whole range of practical applications seems out of the question. Two extreme cases are considered in the present paper. In the first of these it is assumed that the aim of an optical design is to produce an image which is directly similar to the object. This is appropriate when no process of image interpretation or reconstruction is envisaged. In the second case, the aim is to produce an image containing the greatest possible amount of information about the object, without regard to the complexity of the interpretation processes which may be needed to extract it. For the first case, a criterion of image fidelity is proposed in Section 2.4 which gives a numerical measure of the resemblance of image to object in terms of the transmission factors of the optical system. In the second case, assessment is based on the information content of the image in Shannon's sense. This depends not only on the transmission factors of the system but also on the statistical properties of the presumed object set and of the unpredictable fluctuations which necessarily disturb observation; the analysis is carried through in Section 3. In Section 4 the assessment of optical images is discussed in terms of these two criteria.

Significant improvement in the signal-to-noise performance of television signals has been obtained through the application of comb filtering techniques. This improvement is achieved by removing the inherent redundancy in the television signal through linear prediction and by utilizing the unique noise-rejection characteristics of the receiver comb filter. Theoretical and experimental results describe the signal-to-noise ratio and picture-quality improvement obtained through the use of baseband comb filters and the implementation of a comb network as the loop filter in a phase-lock-loop demodulator. Attention is given to the fact that noise becomes correlated when processed by the receiver comb filter. The subjective effect of line-to-line and pictureelement-picture-element-picture-element (PE-PE) correlation on noise visibility is discussed and demonstrated.

MANY are familiar with raster patterns, particularly the example seen on the face of television receivers. In order to present the most picture information with least bandwidth, such regular raster patterns are stabilized by synchronizing signals, derived by subdividing the frequency produced by a piezoelectric crystal stabilized oscillator. However, the simplicity of using an independent, stable oscillator for each of the vertical and horizontal deflection waves has been appealing. This was especially so for the extensive circuitry and subdivision needed to furnish the high-speed scans and quadruple interlace required when Avion-Alexandri carried out a U.S. Air Force RADC contract to pursue the experiments in electronic image processing done at the National Bureau of Standards.1

A compact parallel image processing system concept has been developed. The main features of this system is the use of off-axis paraboloidal mirror segments as collimating, Fourier transforming and image reconstructing elements, and the use of a GaAs laser diode as the coherent radiation source. Preliminary experiments to demonstrate the usefulness of this system have been performed.

A specific relationship between some of the current knowledge and thought concerning human vision and the problem of controlling subjective distortion in processed images are reviewed.

Golay hexagonal pattern transforms are position independent local operators for use in transforming or altering binary images. The hexagonal tessellation is preferred because it removes the connectivity ambiguity present in the square or checkerboard tessellation. Golay transforms also may be applied to multilevel or "gray" images by encoding such images as a registered stack of binary image planes. The general Golay transform creates a new binary image (the output image) from as many as three stacked input images. Simpler Golay transforms merely alter the binary pattern contained in a single image plane, i.e., the same plane acts as both input and output. Because it is slow and cumbersome to perform Golay transforms using a general-purpose computer, fast special-purpose computers have been built for this purpose which may be programmed in a new image processing language called Glol (Golay logic language). It has been found, using both synthetic images as well as images taken from the real world, that Golay transforms are useful in feature enhancement and extraction. Several illustrative examples are provided.

In order to determine optimum resolution requirements for digital facsimile systems, a legibility study was conducted. The study was designed to measure the quality of output copy as a function of equipment parameters and copy parameters. The experimental equipment permitted systematic variations in horizontal and vertical resolution, scan direction, and simulated transmission noise; the test documents prepared included uppercase and lowercase characters of several sizes. During the course of the overall study, more than 300 subjects read the facsimile output copies; approximately 750 000 responses were accumulated and analyzed. The data are summarized by showing the spatial resolutions required to maintain 97.5 percent legibility for varying character sizes. Measurements were also made on secondary parameters, indicating slight differences in legibility due to scan direction, and a decrease in legibility when type was lowercase rather than uppercase. The decrease in legibility was also measured for a model of channel errors that assumes the use of run-length compression coding. Some of the results of this study can be generalized to other display systems.

This paper describes signal processing in the encrypteddomain, i.e., that after encryption but before decryption. In this framework, signal processing operations can be directly applied to encrypted signals without decrypting of encrypted signals, whereas the ordinary framework encrypts signals for transmission and/or storing but it decrypts them before signal processing operations are applied to. The described framework befits contemporary cloud computing in which not only transmission but also storing and processing are done in the public Internet. Addition to brief survey, two tangible application scenarios are also demonstrated in this paper where a new signal processing algorithm is introduced each.

A nonlinear picture-to-picture transformation is introduced and compared with a straightforward linear transformation. The criterion for comparison is based on the desire to smooth noisy or textured regions while retaining edge definition. Selected examples from a large number of simulations are presented. The transformation presented is believed to be superior to many techniques presently being employed.

An analysis of the input to image processing systems is presented for input images recorded on radiographic film. The effects of combining simple structural elements to produce complex images are discussed. Mathematical models for idealized radiographic images of ribs, pulmonary nodules, and blood vessels are formulated and the effect of various combinations of these models on the frequency spectra of the complex image is examined in detail. The validity of these theoretical predictions is demonstrated by using a radiograph of real structures. The implication of these results for image processing by matched filters is discussed.

In this paper we present some new ideas on pattern recognition of bubble chamber photographs. We have found global transformations that reduce circular tracks to a point in a two-dimensional angle-curvature space. The performance of this tracking method on a sample of bubble chamber events is presented and planned improvements are discussed.

Recent advances in digital-computer and optical techniques have made frequency-domain image processing both practical and advantageous. Errors can be introduced in processed images that are peculiar to frequency-domain processing. We present some expressions describing the quantitative effects on processed images of different types of frequency-domain errors. The situations in which these errors arise are discussed. The various error situations were simulated on a digital computer and the resulting corrupted images are presented so that an appreciation of the subjective effects of the errors on image quality may be obtained.

The approximation of arbitrary two-dimensional curves by polygons is an importanttechnique in image processing. For many applications, the apparent ideal procedure is to represent lines and boundaries by means of polygons with minimum number of vertices and satisfying a given fit criterion. In this paper, an approximation algorithm is presented which uses an iterative method to produce polygons with a small—but not minimum—number of vertices that lie on the given curve. The maximum distance of the curve from the approximating polygon is chosen as the fit criterion. The results obtained justify the abandonment of the minimum-vertices criterion which is computationally much more expensive.

Impulse noise removal is a very important preprocessing operation in many computer vision applications. Usually it is accomplished by median filter with excessive sorting and therefore large power. This paper presents a new design of 2D median filter that utilizes a simple conditional filtering technique, executes fewer computations than related designs while achieving superior image quality. Experimental FPGA implementation of the proposed filtering scheme is compact, fast and low-power consuming.

Hough has proposed an interesting and computationally efficient procedure for detecting lines in pictures. This paper points out that the use of angle-radius rather than slope-intercept parameters simplifies the computation further. It also shows how the method can be used for more general curve fitting, and gives alternative interpretations that explain the source of its efficiency.

This reviews a wide range of techniques for image analysis which, although widely different in practical details, share a common mathematical background. Fourier and Fresnel transforms are emphasised,for apart from their role in diffraction theory, they form background to a wide range of image processing systems, including x-ray cameras, holography, sideways-looking radar, and aperture synthesis as applied to radio astronomy. An examination of the connection between Fresnel and Fourier transforms suggests methods for the computer generation of holograms. Use of a transform proposed by Girard, related to the Fourier transform, is examined as well as a series of binary codes based on Hadamand matrices.