Showing papers on "Grayscale published in 1989"

A unified coding method of dithered image and text data using micropatterns

Abstract: This paper introduces a unified coding algorithm for dithered image and text data. When a gray scale image is represented by binary pseudo-half-tone, various binary patterns representing the same gray scale are generated based on the degree of freedom in the dither matrix. Then one of the binary patterns is selected to represent the corresponding text data. The proposed algorithm permits approximately 70k bytes of text data to be embedded into a 256 × 256-pixel image. It enables the transmission and handling of the mixture of image and text data without processing the two types of data separately.

Automatic inspection method

Abstract: A method for automatically inspecting articles or work pieces uses a solid state television camera to obtain images of the article. An edge enhancement is done to obtain a first and a second threshold level which are dilated to eliminate noise edges. An edge correlation is then performed to determine orientation of the article. Gray scale or gray level imaging of the surface of the device is then performed and compared against a known device surface in order to determine acceptability of the device under inspection. The gray scale imaging techniques used are robust gray scale image processing that are tolerant to significant variations in image luminance or image degradation and is capable of identifying and classifying image features consistently while in the presence of such luminance variations. The data is then statistically characterized and the results used for real time statistical process control of the work piece process.

Efficient data storage system for gray-scale printers

Abstract: Apparatus and method for producing a page output from electronic input data consisting of text and line graphics information and of pictorial information. The text and graphics information is converted to two-bit per pixel data and stored in a page buffer. The pictorial information is originally stored at its originating pixel resolution and at a bit level sufficient to represent the full color content. This pictorial data is expanded to a finer pixel resolution at a four-bit level, per color, at the time data is to be merged with the text and graphics data. The merging is accomplished in a band or line buffer which combines the two-bit and four-bit data. A location table is used to keep track of the bit level transitions and to signal the output device that the data is in a particular format.

Weighted mapping of color value information onto a display screen

Abstract: A method and apparatus for assigning color values (or gray scale) to picture display locations. A large frame buffer is written into with each memory location (preferably one bit) corresponding to a separate element of an image. The frame buffer contents are then mapped into a smaller space. The frame buffer memory has a color value assigned to each location of the memory. The memory has a larger number of locations than the number of color picture display locations. Each location is also assigned one of a plurality of weights. A number of color patterns are created and stored, with each color pattern being a bit pattern designed to produce the desired color when applied to the color values of the memory locations. A representation of a desired image is written into the memory using the color patterns, with each memory location corresponding to a separate element of the image. A group of bits in adjacent memory locations are combined with their weighting factors to produce each color value for each color picture display location.

Automatic adaptive anisotropic digital filtering and biasing of digitized images

Abstract: Adaptive anisotropic digital filtering is automatically applied to the graycale values of substantially of all the pixels in at least a portion of a digital image by, for each such pixel, selecting and angularly orienting the matrix of coefficients of an anisotropic filter kernel as a weighting function of the gray scale values of pixels in eight, 45 degree sectors under the kernel, and then performing a convolution of the gray scale values of pixels under the kernel with the rotated kernel to generate a filtered value for the center pixel. Local brightness of the image is adjusted either in conjunction with anisotropic filtering or separately by comparing for each pixel the average gray scale value of the pixels under the kernel with a reference value and applying a bias function to the center pixel grey scale value to brighten or darken the image dependent upon the results of the comparison.

Three-Dimensional Object Recognition Using Range Data

Abstract: For the past two decades, most computer vision research has been concerned with digitized gray scale intensity images as sensor data. Digitized intensity images do not, however, contain explicit information about depth or range. More recently, digitized range data from both active and passive sensors has been used for object recognition and image understanding. In this paper we present a 3-dimensional range data recognition scheme. This scheme is based on the association of a set of geometric features to a surface which approximates the surface of an unknown object. A key feature of this system is its efficient use of dense range data.

Page buffer system for an electronic gray-scale color printer

Abstract: A data storage system for an electronic color printer which stores data according to the type of information the data represents. When the data represents area fill and image information, the data is stored in the page buffer according to mode A of the invention wherein a plurality of pixels are all defined to have the same color with varying luminance levels. This color is defined in the memory in a uniform color space format. When the data to be stored is representing text or line graphics information, the data is stored in the page buffer according to mode B of the invention. In mode B, two-bit binary values in the page buffer are assigned to each pixel of a multiple-pixel cell. These two-bit values point to additional bytes in the memory block of the page buffer which in turn point to discrete colors in spectrums of 256 colors. Additional data indicates whether the output device is to reproduce the colors by halftoned or non-halftoned techniques. Thus, each pixel within the pixel cell can be printed in a color selected by the color portion of the page buffer. According to mode C of the invention, three separate color maps are defined in binary form by the bit patterns stored in the page buffer memory. Also in mode C, the method used to produce blacks in the output page is specified. By standardizing on the memory allocated to the page and utilizing this memory in different ways according to the nature of the inputted information, the printed page can be accurately stored with a minimum of memory space and without a reduction in perceived printing quality.

Software invisible selective monochrome to color signal converter for medical diagnostic imaging

Abstract: A medical diagnostic imaging apparatus (A) creates an image representation which is stored in an image memory (24). A video processor (26) generates a monochrome video signal from the data stored in the image memory. A monochrome to color video signal converter (B) converts the gray scale designations of the monochrome video signal to hue scale designations of a color video signal. More specifically, the gray scale values of the monochrome signal are digitized by an analog-to-digital (32) and used as addresses for a plurality of look up tables (36r, 36g, 36b, 64r, 64g, 64b). Each set of three look up tables (30, 60, 66) is preprogrammed with appropriate transfer functions, such as the transfer functions (40, 42, 44) of FIG. 2. Each look up table puts out an appropriate intensity designation for one of the three color components of the video signal. A digital-to-analog converter (50) converts the look up table outputs to three components of an RGB or other appropriate color video signal. Switches (72) are controlled by a switch controller (74) to switch among two or more sets of look up tables during each frame of the monochrome video signal. Each seat of look up tables has different transfer functions, such as a monochrome to color transfer function and a monochrome to monochrome transfer function. In this manner, some quadrants or other regions (78a, 78b, 78c, 78d) of the video display on a video monitor (C) are in color and other quadrants are in black and white. This enables multiple diagnostic images to be displayed concurrently in quadrants of the video display in either a monochrome or color format--whichever is more appropriate to the nature of the image.

Apparatus and method for gray scale display

Abstract: Disclosed is a system selecting one out of a plurality of gray scale signals for each color information in display information including color information of a plurality of colors for providing monochromatic gray scale signals at multiple levels corresponding to the display information, or, when multiple colors are produced by combining a plurality of colors, selecting one out of a plurality of gray scales for each color corresponding to gray scales of the multiple colors, to thereby attain a multi-level monochromatic emulation display.

Efficient Recognition of Partially Visible Objects Using a Logarithmic Complexity Matching Technique

Abstract: An important task in computer vision is the recognition of partially visible two-dimensional objects in a gray scale image. Recent works addressing this problem have attempted to match spatially local features from the image to features generated by models of the objects. However, many algo rithms are considerably less efficient than they might be, typ ically being O(IN) or worse, where I is the number offeatures in the image and N is the number of features in the model set. This is invariably due to the feature-matching portion of the algorithm. In this paper we discuss an algorithm that significantly improves the efficiency offeature matching. In addition, we show experimentally that our recognition algo rithm is accurate and robust. Our algorithm uses the local shape of contour segments near critical points, represented in slope angle-arclength space (θ-s space), as fundamental fea ture vectors. These feature vectors are further processed by projecting them onto a subspace in θ-s space that is obtained...

Method for thresholding an image signal

Abstract: This invention relates to a method for converting a grayscale image to a bitonal image which provides improved tonal rendition with minimal loss of resolution. The invention attenuates the low spatial frequency component of the digital image and uses a similarly attenuated thresholder to convert the image to a bitonal image. When used with a dither type thresholder, this technique allows for simultaneous "continuous tone" and "line art" thresholding with minimal circuit complexity.

Apparatus for non-linear error diffusion thresholding of multilevel video images

Abstract: Apparatus for converting multilevel video images into a bi-level image having an accurate rendition of the original multilevel grayscale of the image. The apparatus can correct for non-linearities introduced by current error diffusion techniques.

Electromagnetic gray scale printer

Abstract: A gray scale image poster printer reproduces a digitally stored bit map image on a printer using an electrostatic and magnetic toner to generate gray scale images by expanding each line of the original stored image into a plurality of subpixels along the horizontal scanning lines and by synchronizing the printing of the subpixel lines with a changing magnetic field that changes the amount of toner deposited in each subpixel.

Active matrix liquid crystal display fabrication for grayscale

Abstract: A structure and method of fabricating a active matrix display with halftone grayscale and wide viewing angle, having an active matrix array and a control capacitor array fabricated on separate substrates.

Apparatus for thresholding an image signal

Abstract: This invention relates to an apparatus for converting a grayscale image to a bitonal image which provides improved tonal rendition with minimal loss of resolution. The invention attenuates the low spatial frequency component of the digital image and uses a similarly attenuated thresholder to convert the image to a bitonal image. When used with a dither type thresholder, this technique allows for simultaneous "continuous tone" and "line art" thresholding with minimal circuit complexity.

Antialiasing: A technique for smoothing jagged lines on a computer graphics image—an implementation on the Amiga

Abstract: Images displayed on computer graphics displays often suffer from the presence of aliasing artifacts that give a jagged appearance to lines or polygon edges displayed on the screen. This paper details the problems associated with these artifacts and presents a method for drawingantialiased lines—ones in which the artifacts have been considerably reduced. The line-drawing routine is further developed to incorporategamma correction, to take into account the nonlinear relationship between the intensity of the light emission from the phosphor of the monitor and the grayscale values used to control the intensity on the screen.

Mathematical Morphology and Its Application in Machine Vision

Abstract: Mathematical morphology provides an efficient tool for image analysis. We study the problem of flaw detection in materials which are represented by very poor contrast digital images. An algorithm for flaw detection in the case of glass matte surfaces has been developed. The object skeletons within the binary images are obtained and directional connectivity information in the skeletons is used to discriminate noise patterns from flaws according to a specified criteria. After the discrimination process, the remaining skeletons correspond to flaws and can be employed to recover the shape of flaws. An alarm flag may be turned on if the sizes of the detected flaws are found to exceed industrial standards. In the case of a grayscale image, the image is converted to a binary version by using an adaptive threshold algorithm, then the algorithm for binary images is applied. Experimental results have been obtained for both binary and grayscale digital image data.

Image and Signal Processing in Diagnostic Ultrasound Imaging

Abstract: An overview of signal-processing techniques used in the acquisition, display, manipulation, and analysis of echo scan data is presented. The principles of time-gain compensation, selective enhancement, log compression, fill-in interpolation, edge enhancement, image updating, write zoom, gray scale mapping, black/white inversion, freeze frame, frame averaging, read zoom, thresholding, contrast enhancement, filtering, and region-of-interest definition are reviewed. The concept of gray scale mapping, which dictates how the stored scan data are displayed, is explained with many illustrative examples.

High speed window and level function modification for real time video processing

Abstract: A CT scanner (10) non-invasively examines a region of interest of a patient to create an image representation that is stored in an image memory (14). Each pixel of the image representation has a relatively large number of bits of radiation intensity resolution, e.g. 14 bits or 16k levels, which is larger than the gray scale resolution of a conventional video monitor (24), e.g. 8 bits or 256 levels. A look-up table (38) digitally filters each pixel value with digital filter values to reduce the number of levels of each pixel value to the number of gray scale levels displayable by the video monitor. While the image is being displayed, the operator selectively adjusts the digital filtering to optimize the displayed image for the intended diagnostic purpose. During the vertical flyback or other non-display periods of the video monitor, a central processor (30) generates most significant bits of addresses that read digital filter longwords from a filter memory (44). A multiplexer (54) breaks each word into a plurality of filter values or bytes which are serially conveyed to the digital filter look-up table. A least significant bit address generator (62) generates the least significant bits of the address for each filter value concurrently with its conveyance to the look-up table. The multiplexer and least significant bit address generator are clocked at a faster rate than the central processor such that within one read clock pulse of the central processor, a plurality of digital filter values are loaded into the digital filter look-up table. In this manner, image filtering via look-up table in real time is enhanced through an improved, faster loading method.

Color separation using eigen filtering of a multispectral gray-scale image sequence

Abstract: The identification and separation of colors or colored objects using only gray-scale images are investigated. A sequence of multispectral gray-scale images is formed by successive imaging through a sequence of optimal filters. Using the signature vector representation of colors obtained from these gray-scale images, the eigen imaging technique is used to generate the eigen filter vector and then the resulting eigen image for separation of one (desired) color from one or two other (undesired) colors. In the eigen filter image produced by this technique, two colors that are not perceptually similar to each other are separable. That is, the gray-scale values of the locations of the desired color are enhanced while those of the undesired colors are suppressed. The signature vectors and the eigen filter vector are not very sensitive to a change in the camera parameter or to the variations of a color. >

Methodology in design of a page width a-Si TFT linear image sensor

Abstract: A circuit design method for a matrix driven linear image sensor has been developed. Relations between the circuit parameters and the performance of the sensor are resolved by analysis of the equivalent circuit. Optimizing for gray scale performance is accomplished by adjustment of circuit parameters. The effectiveness of this method has been demonstrated by the development of an actual sensor having the capability of resolving 16 levels of gray scale.

High-resolution computerized color transformation of real-time gray scale ultrasound images.

Abstract: Contemporary real-time ultrasound images are constructed of graduated shades of gray. The practical range of echo contrast than can be depicted is therefore limited. The use of color as well as intensity would potentially increase the amount of information available and possibly augment tissue texture contrast. Previous efforts to color encode ultrasound images have not been of adequate visual resolution, and have not produced simultaneous or real-time results. Described and illustrated here is a microcomputer-based system that successfully produces high-resolution simultaneous real-time pseudocolor transformation of real-time ultrasound images. The system accepts the composite video output in any ultrasound machine, and the specific color scheme may be chosen to suit the operator. It is proposed that such color enhancement improves visual clarity of fine fetal anatomy by highlighting tissue-tissue contrast and tissue-fluid interfaces.

Color separation using eigen filtering of a multispectral gray-scale image sequence

Abstract: Of interest in this project are the identification and separation of colors or colored objects using only gray-scale images. A sequence of multispectral gray-scale images is formed by successive imaging through a sequence of optical filters. Using the signature vector representation of colors obtained from these gray-scale images, the eigen imaging technique is used to generate the eigen filter vector and then the resulting eigen image for separation of one (desired) color from one or two other (undesired) colors. In the eigen filter image produced by this technique, two colors that are not perceptually similar to each other are separable. That is, the gray-scale values of the locations of the desired color are enhanced while those of the undesired colors are suppressed. The signature vectors and the eigen filter vector are not very sensitive to a change in the camera parameter or to the variations of a color.

Quantitative Luminance And Colour Representation With CRT Displays

Abstract: Colour displays in image processing admit grey scales as well as colour scales for the visual representation of image information. Pseudocolours can be used to enhance the discriminability of different parts of the image. Luminance scales, on the other hand, are preferred for representing fine detail as human colour vision is limited to relatively low spatial frequencies. In the present paper, the generation of quantitative luminance and colour scales with CRT displays is discussed. This includes the colour characteristics of CRTs as well as a recapitulation of the CIE 1931 (X, Y, Z) tristimulus colorimetry system. The CIE 1976 UCS diagram (u', v') is used as an approximation to a perceptually uniform representation of chromaticity. On this basis, it is shown how, for each pixel, luminance and colour (hue) can be chosen independently. In order to add colour as a further visual dimension to greyscale images, a set of equiluminant hues is proposed for each luminance level. The hues are chosen from equidistant steps around a circle in the (u', v') chromaticity diagram. This choice of colours is particularly suitable for the visual representation of a cyclic quantity like phase angle.

Isolating contour information from arbitrary images

Abstract: Aspects of natural vision (physiological and perceptual) serve as a basis for attempting the development of a general processing scheme for contour extraction. Contour information is assumed to be central to visual recognition skills. While the scheme must be regarded as highly preliminary, initial results do compare favorably with the visual perception of structure. The scheme pays special attention to the construction of a smallest scale circular difference-of-Gaussian (DOG) convolution, calibration of multiscale edge detection thresholds with the visual perception of grayscale boundaries, and contour/texture discrimination methods derived from fundamental assumptions of connectivity and the characteristics of printed text. Contour information is required to fall between a minimum connectivity limit and maximum regional spatial density limit at each scale. Results support the idea that contour information, in images possessing good image quality, is (centered at about 10 cyc/deg and 30 cyc/deg). Further, lower spatial frequency channels appear to play a major role only in contour extraction from images with serious global image defects.

Applications of range image sensing and processing

Abstract: In any machine vision problem, one is concerned with analyzing an image so as to produce a description of the image relevant to the task at hand. Most industrial problems have to do with the inspection, manipulation or measurement of three dimensional objects in a three dimensional workspace. Thus, machine vision systems used in these problems are often required to provide geometric descriptions of object and and workspace. The desired descriptions can be formed by implicit or explicit methods. Classical machine vision research seeks to construct three dimensional representation of objects in the field of view implicitly from one or more gray scale luminance images. The central idea behind this approach is that shape characteristics can be inferred from luminance variations observed in the image through the use of a variety of physical, optical and conceptual models. The system forms a description of the scene based on the information from the models, features from the images and control flow supplied by the particular reasoning approach used.

Improvement In Feature Interpretation By Means Of Polar Coding

Abstract: The paper presents improvement achievable in pattern recognition systems based on polar coding of images. The idea of polar coding of images is not a new one. Existing methods can be improved if, instead of radius and angle as the representatives of image boundary, other features are extracted, such as a histogram representing concentric luminous intensity of the image. The histogram is formed in such a way that it shows luminous intensity of concentric rings having center in template's centroid. The number of pixels per ring increases with growing radius and it is the greatest for outmost diameter. Therefore, integration of luminous information per ring must be normalized in order to form a histogram representation of polar image. Binary images are analyzed and generalization for gray scale images is given.

Image processing system and generation of image

Abstract: PURPOSE: To reduce the data volume required for image expression by separately expressing an image with high-resolution blackand-white image data and low- resolution gray scale image data. CONSTITUTION: A high-resolution gray scale image is expressed in two separate image forms, namely, a form of a high-sampling density black-and-white image and a form of a low-resolution and low-sampling density gray scale image. Consequently, one image form can be used independently of the other, and both of them are coupled again thereafter to generate reconstituted high- resolution gray scale image data which expresses the image. Thus, the storage capacity required for storage of image data or the transmission band width required for transmission of image data is reduced to generate high-resolution gray scale image data.