Showing papers on "Edge enhancement published in 1979"

Electronic rescreen technique for halftone pictures

Abstract: A method for rescreening a halftone image to produce an edge-enhanced halftone copy from a halftone original. The halftone original is scanned by a raster input scanner and the resultant analog voltage is compared to a reference voltage to produce a one bit per pixel bit stream, where a pixel is defined as the smallest image (picture) element discernable by the system. For example, in a raster input scanner using a CCD array, the smallest picture element, pixel, is the analog voltage output of one CCD cell. This voltage subsequently can be converted to a digital gray scale representation requiring a plurality of bits per pixel, or either analog or digital representation can be compared to an analog or digital reference voltage to produce a one bit pixel. A six bit per pixel gray scale output is produced therefrom by adding an integrated value and an edge enhancement value for each input pixel received. The integrated value is calculated by summing the number of one bits in the seven by nine bit section surrounding each pixel. The edge enhancement value is calculated by determining the difference between the number of one bits in the right and left halves, and upper and lower halves, of the six by seven bit section surrounding each pixel. A set of equations is used to process these differences to produce an edge enhancement value which is added to the integrated value. From this six bit per pixel gray scale output the six bit output can be preserved, or a halftone copy can be produced by any well-known process. A simple and inexpensive circuit to perform the above functions at high data rates is also disclosed.

Method and apparatus for producing optical displays

Abstract: Method and apparatus for creating optical displays from a real optical scene with an optical feedback circuit projecting a parameter of the original scene (18) for combination with the original scene itself or an image thereof. The feedback circuit may influence the parimetric image in many ways to influence the combined optical display. For instance, the parametric image may be a negative of the real scene to produce a null combined display showing motion where the parametric image is time delayed or the parametric image may be defocused to produce a combined display with edge enhancement. The feedback circuit may project a vertical parametric image to create fixed relation combined displays or the feedback circuit can project real parametric images continuously to create a combined display which changes progressively as a function of the relation between original and parametric images. The method and apparatus may be used for a variety of purposes such as motion detection in security devices or live sperm counting or real image enhancement in biological microscopy.

Median Masking Technique For The Enhancement Of Digital Images

Abstract: A nonlinear masking technique has been developed which characterizes digital images by local measures of the median and the median absolute deviation (MAD). Space-variant enhancement is elicited by modifying the local MAD as calculated over a moving window in the original image. The method is found to be effective in edge enhancement and noise cleaning operations.© (1979) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

White light optical processor for edge enhancement and spectral filtering.

Abstract: A white light optical processor is described using partial coherence theory. The application of the processor to both edge enhancement and band-pass filtering of imagery is discussed. The spectral components of the spatial frequency content of images can be separated or filtered if the various spectra do not overlap by a distance determined from the spatial spectrum of the mutual intensity function of the image illumination. The results of an experimental and computer evaluation of the processor are presented.

Heuristic Approach For Video Image Enhancement

Abstract: Video Image Enhancement through adaptive noise filtering and edge sharpening is presented. The basic concepts behind this technique are the fact that with some kind of image segmentation, noise filtering can be performed in the nearly uniform region and edge sharpening only near an edge. The resulting algorithm is nonlinear and adaptive. It adapts globally to the input SNR and locally to the gradient magnitude. Implementation is quite simple. Performance is nonlinear and depends on the SNR of the original image. Effective video signal-to-noise ratio can be improved with minimal observable contouring effect, degradation in spatial resolution, and other artifacts.

Digital Boundary Detection Techniques For The Analysis Of Gated Cardiac Scintigrams

Abstract: Boundary detection in conventional nuclear medicine scintigrams is often difficult for several reasons. First, scintigrams generally have a low signal-to-noise ratio. Second, edge structures are poorly defined because of the low resolution of gamma ray cameras; and finally, edge contrast is usually reduced by foreground and background activity. In this paper we report on heuristic approaches we have taken to solve these problems and to develop programs for the display of cardiac wall notion and for the automatic determination of left ventricular ejection fraction. Our approach to processing cardiac scintigrams entails several steps: smoothing, edge enhancement, thresholding, thinning and contour extraction. We discuss each of these steps in light of the goal of producing cardiac boundaries which are spatially and temporally smooth and continuous. Boundary detection results are presented for some selected clinical images.© (1979) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Implementation of a picture digitizer and display for image processing operations

Abstract: : The purpose of this study was to implement Spatial Data System's EyeCom Picture Digitizer and Display on Digital Equipment Corporation's PDP-11/50 minicomputer using the real-time operating system RSX-11M. The tasks involved included the following: operating the EyeCom on the RT-11 operating system to investigate its image processing capabilities; implementing of Drexel University's software conversion package for the RSX-11M operating system; preparing a EyeCom Operator's Manual for RSX-11M; developing a Pseudocolor option using the RAMTEK GX-100A Color Raster Scan Display. With the completion of these tasks, the EyeCom can now do the following image processing operations: picture digitization, magnification, averaging, gray-scale reduction, contrast enhancement, spatial filtering, shifting, reversal, edge enhancement, picture noise reduction, and histogram distribution. The result of these operations can be displayed on the RAMTEK GX-100A Color Raster Scan Display. (Author)