Showing papers on "Edge enhancement published in 1976"

Real-Time Image Enhancement Techniques

Abstract: Most image enhancement techniques are not suitable for real-time applications. This paper presents two contrast enhancement techniques that can work at TV rates with fairly simple hardware.© (1976) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Halftone method with edge enhancement and Moiré suppression

Abstract: A method has been found for separating control of high and low spatial frequencies in a continuous-tone image during conversion to a halftone (binary) form for printing. This method allows edge enhancement, while simultaneously limiting creation of spurious Moire patterns due to image frequencies near the halftone screen frequency. Macroscopic grey scale control is achieved by determination of average grey level by low-pass filtering of the image. This information is used to set halftone dot size. Microscopic or detail contrast is controlled as in the ordinary halftone process, that is, by screen shape and screen modulation, which therefore affects partial dot structure. In the absence of detail, the results of this process match ordinary halftones. In detailed areas, however, the low-frequency control limits generation of spurious low-frequency Moire patterns, while free choice of screen modulation allows enhancement of edges up to the common limit where image noise becomes dominant.

Evaluation of xeroradiographic image quality.

Abstract: A theory of edge enhancement has been developed to describe xeroradiographic images of linear step objects. The theory is shown to give an accurate description of the relationship between edge enhancement, subject contrast, radiation exposure, selenium charging potential and developer bias potential. An optimal transmitted x-ray exposure exists which gives the maximum edge enhancement. For low contrast structures, this same optimal exposure was found to yield the most acceptable images as judged subjectively. This finding has led to the successful application of automatic exposure termination in mammographie examinations using xeroradiography.

Electrostatic fountain developer

Abstract: A fountain for moving liquid toner into engagement with a receptor for developing an electrostatic image into a visible image A fountain for providing improved edge enhancement in an image, and incorporating an electrode positioned at the bottom of a liquid toner pool formed by electrical insulating end, side and bottom members

A real-time optical data processing device

Abstract: A novel liquid-crystal electro-optical device useful as a real-time input device in coherent optical data processing is described The device is a special adaptation of an ac photoactivated liquid-crystal light valve, and utilizes a hybrid field effect (45 deg twisted nematic effect in OFF state and pure optical birefringence of the liquid crystal in ON state) A thin-film sandwich exerts photoelectric control over the optical birefringence of a thin liquid-crystal layer Liquid-crystal layer thickness is successfully reduced without image degradation The device offers high resolution (better than 100 lines/mm), contrast (better than 100/1), high speed (10 msec ON, 15 msec OFF), high input sensitivity, low power input, low fabrication cost, and can be operated at below 10 V rms Preliminary measurements on device performance in level slicing, filtering, contrast reversal, and edge enhancement are under way

Rapid, low-cost, image analysis through video processing

Abstract: Remote Sensing now provides the data necessary to solve many resource problems. However, many of the complex image processing and analysis functions used in analysis of remotely-sensed data are accomplished using sophisticated image analysis equipment. High cost of this equipment places many of these techniques beyond the means of most users. A new, more economical, video system capable of performing complex image analysis has now been developed. This report describes the functions, components, and operation of that system. Processing capability of the new video image analysis system includes many of the tasks previously accomplished with optical projectors and digital computers. Video capabilities include: color separation, color addition/subtraction, contrast stretch, dark level adjustment, density analysis, edge enhancement, scale matching, image mixing (addition and subtraction), image ratioing, and construction of false-color composite images. Rapid input of non-digital image data, instantaneous processing and display, relatively low initial cost, and low operating cost gives the video system a competitive advantage over digital equipment. Complex pre-processing, pattern recognition, and statistical analyses must still be handled through digital computer systems. The video system at the University of Wyoming has undergone extensive testing, comparison to other systems, and has been used successfully in practical applications ranging frommore » analysis of x-rays and thin sections to production of color composite ratios of multispectral imagery. Potential applications are discussed including uranium exploration, petroleum exploration, tectonic studies, geologic mapping, hydrology sedimentology and petrography, anthropology, and studies on vegetation and wildlife habitat.« less

Image characteristics of liquid developed electron radiographs.

Abstract: This paper presents electron radiograph studies using the new Xonics liquid development system described only briefly previously. Results indicate: (a) higher contrast images with reduced but useful edge enhancement; (b) adjustable contrast; (c) reduced exposure vs. aerosol development; (d) sharp, low artifact images to densities greater than 2.5; and (e) possibility of nongrid scatter control in some situations.

Image Format and Viewers for Computerized Tomographic Scanners

Abstract: Little technical information has been made available on CT image format or viewers. For large matrix displays (320 x 320 or 512 x 512), a high quality TV monitor with a bandwidth of 10 MHz or greater is required. If only a single field of a two to one positive interlaced TV monitor is displayed, an 875 line rate TV would be required in order to display the entire matrix. For image recording, a transparency system such as a multi-format unit or a 105 mm roll film camera will generally provide the best results. Finally, in order to improve the final CT image, various picture processing routines may be used. These include pre- and post-reconstruction smoothing, edge enhancement and image subtraction.© (1976) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

An Edge Detecting System

Abstract: Publisher Summary This chapter provides an overview of an edge detecting system. In pattern recognition, an edge detecting transformation is usually carried out by convoluting the input image with a selected operator by the means of a digital computer. The location of an edge in an image is indicated by curves along which there is an abrupt grey level change. One approach to edge detection is to perform the operation of differentiation. The brightness gradient at a point in a picture is proportional to the difference between the maximum and minimum grey levels in a small circle centered at that point. This chapter describes a real-time edge detecting apparatus, an image differentiator, incorporating a flying spot scanner (FSS). Applications of this apparatus to contrast enhancement and also to a color pattern display system that allows the direct observation of edge sharpness converted into color patterns are included. Results show that the system has many advantages. The expected applications for the system are: (i) preprocessing or feature extraction for pattern recognition; (ii) image enhancement; and (iii) coloring character or pattern edges with different colors.