Showing papers on "Image processing published in 1971"

Image processing

Abstract: Image processing techniques find applications in many areas, chief among which are image enhancement, pattern recognition, and efficient picture coding. Some aspects of image processing are discussed--specifically: the mathematical operations one is likely to encounter, and ways of implementing them by optics and on digital computers; image description; and image quality evaluation. Many old results are reviewed, some new ones presented, and several open questions are posed.

Reconstruction of pictures from their projections

Abstract: There are situations in the natural sciences and medicine (e.g. in electron microscopy and X-ray photography) in which it is desirable to estimate the gray levels of a digital picture at the individual points from the sums of the gray levels along straight lines (projections) at a few angles. Usually, in such situations, the picture is far from determined and the problem is to find the “most representative” picture. Three algorithms are described (all using Monte Carlo methods) which were designed to solve this problem. The algorithms are applicable in a large and varied number of fields. The most important uses may be the reconstruction of possibly asymmetric particles from electron micrographs and three-dimensional X-ray analysis.

Feature Extraction by Golay Hexagonal Pattern Transforms

Abstract: 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.

Image modification of motion pictures

Abstract: Individual image areas of a previously recorded motion picture scene can be modified electronically despite relative movement of such areas from frame to frame. Video values for each image element are stored in digital form in the memory of a general purpose computer in association with identifying addresses. A selected object area to be modified is then defined by a list of addresses of the image elements bounding the object. Such boundary addresses are derived partly manually or visually by reference to a CRT display of a selected frame, with assistance from the suitably programmed computer which automatically extends the boundary address list from frame to frame. The computer is then programmed to recover from memory the video values for image elements within the area defined by each boundary address list, to perform the desired modification of each value, and to return the modified values to memory. The modification of each value typically requires reference to other image elements in the same frame or to corresponding image elements of adjacent frames, with computation of functions such as averages of the video values for such elements. Useful types of modification include changes of definition, contrast, hue and brightness, elimination of unwanted objects, reduction of graininess and other random noise, and insertion of color. After completion of the desired modification, each frame or group of frames is again recorded photographically, magnetically or on any desired storage medium.

Reconstructing 3-D Specimens From 2-D Section Images

Abstract: Reseachers seeking a histological determination of microscopic specimen morphology face the basic problem of analyzing three-dimensional microscopic specimens with two-dimensional imaging devices. This tedious task can be done at the microscope but reproduction of images in hard copy or digital form entails the loss of depth information. Quantitative measurements must generally be made on 2-D images. Several methods have been proposed and implemented to obtain and display 3-D images. In this paper we discuss an approach combining digital image processing techniques with stereo display techniques. This allows control of image quality and selection of different 3-D characteristics for display.

Nonredundant Arrays and Postdetection Processing for Aberration Compensation in Incoherent Imaging

Abstract: For incoherent imaging systems, wave-front aberrations can have the effect of severely reducing the contrast of high spatial frequencies. Although postdetection image processing can improve image detail, the success of such an approach is limited by image noise. If a simple spatial filter consisting of a nonredundant array of clear openings in an opaque mask is placed in the pupil plane of the system, postdetection image processing yields a restored image superior to that obtainable from a system without the pupil-plane filter. Experimental results confirm the predictions of the theory.

Connectivity and genus in three dimensions

Abstract: Algorithms for labeling, counting, and computing connected objects in binary three dimensional array

Spatial Differentiation and Integration by Coherent Optical-Correlation Method

Abstract: Optical differentiation and integration are not only interesting from the standpoint of optical computation, but are also important in picture processing. Based on optical correlation, or convolution, and the applications of difference equations, a technique for synthesizing the differentiation and integration filters is presented. This technique compares favorably with other methods which now exist.

Means for evaluating and displaying certain image portions occuring within a total image

Abstract: For TV monitor display of image portions of certain brightness or of certain dimensions as they may occur within a total image taken by a television camera, the invention contemplates feeding the video signal to an adjustable amplitude discriminator. The output signal of the amplitude discriminator is operative upon the video signals in such manner as to blank out or suppress that portion of the total image which is outside the determined image portions. The resulting signal is fed to the monitor. The monitor screen displays a total field, within which the determined image portions appear in correct gray value shading, while the rest of the image field appears in a constant gray value.

Shrunken raster with image insetting

Abstract: Means for insetting a foreground image in a background image in a television display. A combination of electronic and optical elements function to cut out a part of the background image the exact shape of the foreground image. The foreground image is then optically inserted in the cut-out space in the background image.

Modulation Transfer Function of AZ111 Photoresist.

Abstract: For the utilization of photoresist materials it is desirable to describe quantitatively the photoresist image and thereby introduce control over photoresist processing. The photoresist AZ111 has been shown to be a linear image recording medium and a modulation transfer function (MTF) defined and measured. Measured and calculated image profiles in this resist are quite comparable.

Spatial frequency spectra of radiographic images.

Abstract: 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.

Television signal processing device

Abstract: In order to obtain a contour corrected image signal, from which the noise is eliminated in the transition-free zones, a contour signal, derived from a blurred image signal (translating an image which is blurred as compared with that which is translated by the signal which is being processed, but from which the noise has been substantially eliminated) is added, with a suitable gain, to the blurred image signal.

Walsh Functions in Image Processing, Feature Selection and Pattern Recognition

Abstract: Walsh functions have become quite useful in the applications of image processing and feature selection. Due to their inherent efficiency of implementation, (they are a subset of the Reed Muller Codes and Hadamard matrices), they have become popular for coding, enhancement and other signal processing tasks. This paper will briefly describe applications in some of these areas with emphasis on a correlation analysis for justification purposes.

Optical Image Deblurring Methods

Abstract: Greatly sharpened images may be extracted from photographs which have been blurred either by accident (motion, lack of focus, atmospheric turbulence, etc.) or deliberately, for instance when ‘coded’ in view of special image processing or synthesis applications. Four image-deblurring methods may be distinguished: 1. Coherent optical analogue processing, 2. Incoherent optical analogure processing (non-electronic) 3. Incoherent opto-electronic analogue processing and 4. Digital computer processing. Of these, the methods 1 and 3 are reviewed in some detail, and some previously unpublished experimental results are given for illustration. Particular emphasis is also given to the distinction between image-deblurring methods operating directly in the spatial (image) domain, very powerful but developed so far only in special cases (e.g. defocused and motion-blurred images), on the one hand, and, on the other the spatial-frequency filtering image-deblurring methods, also quite general, but still in an early state of perfection. Both methods may require considerable further work before widespread implementation

Digital techniques for image enhancement of radiographs.

Abstract: This paper deals with digital, position variant and invariant linear and nonlinear techniques for image enhancement (Rozenfeld, 1969). The radiographic system, the image processing and display system, and the human visual system are discussed. The enhancement techniques tailor image content of radiographs to the type of information most useful to the human visual system.

Design of an Experimental Laboratory for Pattern Recognition and Signal Processing

Abstract: An interactive computer-controlled scanning and display system has been in operation at the IBM T J Watson Research Center for two years The system includes two flying-spot scanners, specially interfaced to a process control digital computer, dot-mode and vector displays, analog input and output facilities, and a variety of other experimental equipment The system design and programming support are described and typical applications in scanner control, optical character recognition and image processing are presented

Weather time display

Abstract: A weather-time display, such as for use in a closed-circuit of cable television system, includes a plurality of sensors for producing signals proportional to a corresponding plurality of selected environmental parameters. Those signals are sequentially applied to a meter to which a rotatable mirror is coupled. An image of an indicator is projected onto that mirror and from there it is reflected onto an image plane located at the viewing plane of a video camera. Images of scales calibrated in units appropriate to the sensed parameters are sequentially superimposed with the image of the indicator at the image plane such that sequential composite images of the scales and the indicator are formed for viewing and transmission by the video camera. If desired, and as herein shown, an image of the time may also be superimposed on the composite scale-indicator image at the image plane.

Frequency domain image processing apparatus

Abstract: Images are recorded or reproduced by use of a bank of frequencyresponsive mechanical resonators which may be arranged in a single row or in a plurality of rows. Within a row, the resonators are individually disposed at what correspond to different image element positions. As a result of response of the resonators, either in reflecting light or in making or responding to a record, the action of the resonators is correlated with a recording or reproducing medium so that either an image is produced or an electrical signal is developed that defines an image. Display may be either of the television or facsimile type. Whatever the particular mechanism of reproduction or recording, use is made of frequency-responsive mechanical resonators to define different image element positions in a frequency-domain image processing system.

Accuracy Of Radiologists' Decision Making

Abstract: Reliable studies show that under routine conditions radiologists fail to detect approximately 30% of abnormalities present on chest x-ray films. These failures of detection are perceptual in nature and not due to limitations in such physical parameters as resolution or contrast. There are many image processing techniques that are being proposed to help the radiologist. Most of these techniques have been implemented by us in TV process-ing of x-ray films. Each processing technique was evaluated experimentally using radiologists as observers in a test based on concepts originating from signal detection theory. A numerical value for d', an index of merit, was assigned to each technique according to how well it improved the accuracy of the radiologists' decision making.© (1971) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Digital Video Systems Applied To Product Inspection

Abstract: A real-time, digital, video processing system offers a flexible means for performing high-speed, on-line, automated product inspection. With the capability to digitize and store a 512 x 512 multi-gray level image in 1/30 second as well as subtract a reference image from a new image in a TV frame time, it is possible to perform high-speed inspection of parts, packages and labels. Such a unit can operate as a stand-alone unit or as a pre-processor for a dedicated or time-shared computer. Design trade-offs and examples of specific applications will be discussed.

Coherent Optical Parallel Processing

Abstract: Conventional stereocompilation, whether carried out manually or automatically, involves a sequential point-by-point measurement of x parallax. This paper describes an "instant-profile" correlator, a coherent optical parallel processor which measures and displays x parallax point by point simultaneously rather than sequentially. With this optical processor, one can select any y strip of the overlapping stereo imagery, measure simultaneously the x parallax over the entire strip, and display at the output x parallax as a function of y photocoordinate. All of the overlapping imagery may be processed in this matter by simply scanning of the stereo photographs with a slit. The theory of operation of the optical parallel processor is discussed and experimental results with aerial photography are presented.