Showing papers on "Grayscale published in 1980"

The display of characters using gray level sample arrays

Abstract: Character fonts on raster scanned display devices are usually represented by arrays of bits that are displayed as a matrix of black and white dots. This paper reviews a filtering and sampling method as applied to characters for building multiple bit per pixel arrays. These arrays can be used as alternative character representations for use on devices with gray scale capability. Discussed in this paper are both the filtering algorithms that are used to generate gray scale fonts and some consequences of using gray levels for the representation of fonts including:1. The apparent resolution of the display is increased when using gray scale fonts allowing smaller fonts to be used with higher apparent positional accuracy and readability. This is especially important when using low resolution displays.2. Fonts of any size and orientation can be generated automatically from suitable high precision representations. This automatic generation removes the tedious process of “bit tuning” fonts for a given display.

Techniques For Speckle Noise Removal

Abstract: In this paper, several techniques to reduce speckle noise (more generally signal independent multiplicative noise) in images are studied. The techniques include gray scale modification, frame averaging, low-pass filtering in the intensity and density domains, and application of the short space spectral subtraction image restoration technique in the density domain. Some discussions on the theoretical basis of the techniques studied are given and their performances are illustrated by way of examples.

Radiographic apparatus and method with logarithmic video compression

Abstract: A source of radiation irradiates an area of interest of a patient. An image intensifier receives the x-rays which have traversed the patient and provides an optical image of an x-ray shadowgraph through the examined area of the patient. A television camera converts the optical image into a video signal. A signal processor operates on the video signal by adding an offset signal to the gray scale signal and by logarithmically compressing the gray scale portion of the video signal. An automatic zero circuit is provided which readjusts the offset signal between each horizontal sweep of the television camera. The logarithmically compressed gray scale portion of the video signal and the synchronization portion are received by an image processor. The image processor digitally stores a mask image or shadowgraph of the patient before being injected with an x-ray opaque contrast agent. The image processor also stores in a post contrast image or shadowgraph of the same area of the patient after the patient has been injected with an x-ray opaque contrast agent. The image processor subtractively combines the mask image with the post contrast image to produce a difference image. A video monitor displays the difference image.

Apparatus and method for converting one-bit image data into gray scale image data

Abstract: A method and apparatus 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 thresholded to produce a one bit per pixel bit stream A six bit per pixel gray scale output is produced therefrom by adding an integrated value and an edge ehancement 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

Correction device for color film base

Abstract: PURPOSE:To facilitate an easy adjustemnt for the color balance of the color telecine camera with a high accuracy, thus enchacing the color reproducibility. CONSTITUTION:With preset switch 24 turned off, the color balance error is set for the color film base of each of the R, B and G chromaticity channels via the preset adjuster for gain 25, pedestal 26 and gamma 27 each. The color balance is secured for the color telecine camera in the conventional method and based on the gray scale chart of the monochrome film. Afther this, switch 24 is turned on. As a result, the error component of the color film base is added for each element featuring a good color balance, thus ensuring a high color balance. With correction device of such constitution, the color balance adjustment can be facilitated, thus enhancing the color reproducibility.

Gradient Magnitude as an Aid in Color Pixel Classification

Abstract: : When pixels in a black-and-white image are classified by thresholding their gray levels, gradient magnitude information can be used in various ways as an aid in thresholds selection. This note deals with the use of color gradient magnitude as an aid in classifying pixels based on their colors or spectral signatures.

The Engineer Topographic Laboratories (ETL) Hybrid Optical/Digital Image Processor

Abstract: An optical-digital processor for generalized image enhancement and filtering has been designed and is now under construction. The optical subsystem is a two PROM Fourier filter processor. Input imagery is isolated, scaled, and imaged onto the first PROM. This input plane acts like a liquid gate and serves as an incoherent to coherent converter. The image is transformed onto a second PROM which also serves as a filter medium. Filters are written onto the second PROM with a laser scan-ner in real time. A solid state CCTV camera records the filtered image which is then digitized and stored in a digital image processor. The operator can then manipulate the filtered image using the gray scale and color remapping capabilities of the video processor as well as the digital processing capabilities of the mini-computer. The operator can then try new optical filters and iteratively develop optimum methods of detecting patterns. The goal of this research is to develop automated feature extraction algorithms which will minimize the need for human intervention. This system is currently being assembled at ETL, Fort Belvoir, VA.

Syntactic Approach To Geometric Surface Shell Determination

Abstract: Autonomous terminal homing of a smart missile requires a stored reference scene of the target for which the missle is destined. The reference scene is produced from stereo source imagery by deriving a three-dimensional model containing cultural structures such as buildings, towers, bridges, and tanks. This model is obtained by the precise matching of cultural features from one image of the stereo pair to the other. In the past, this stereo matching process has relied heavily on local edge operators and a gray scale matching metric. The processing is performed line by line over the imagery and the amount of geometric control is minimal. As a result, the gross structure of the scene is determined but the derived three-dimensional data is noisy, oscillatory, and at times significantly inaccurate. This paper discusses new concepts that are currently being developed to stabilize this geometric reference preparation process. The new concepts involve the use of a structural syntax which will be used as a geometric constraint on automatic stereo matching. The syntax arises from the stereo configuration of the imaging platforms at the time of exposure and the knowledge of how various cultural structures are constructed. The syntax is used to parse a scene in terms of its cultural surfaces and to dictate to the matching process the allowable relative positions and orientations of surface edges in the image planes. Using the syntax, extensive searches using a gray scale matching metric are reduced.