Showing papers on "Grayscale published in 1988"

Anti-aliasing raster operations utilizing sub-pixel crossing information to control pixel shading

Abstract: A method and apparatus for performing anti-aliasing of rendered lines, text and images displayed by a workstation on a video display. The anti-aliasing is performed by logically dividing each addressable frame buffer pixel into sixteen sub-pixels and generating a gray scale value for the displayed pixel that is a function of the number of sub-pixels crossed by a portion of a rendered image. The invented circuitry is part of the circuitry used for combining source and destination data which forms the displayed image namely, an anti-aliasing mask and filter, adder/subtractor logic, saturation logic and anti-aliasing logic.

Method for scene-model-assisted reduction of image data for digital television signals

Abstract: A method for scene-model-assisted reduction of image data for digital television signals, whereby a picture signal supplied at time t is to be coded, whereby a predecessor frame from a scene already coded at time t-1 is present in an image store as a reference, and whereby the frame-to-frame information are composed of an amplification factor, of a shift factor and of an adaptatively acquired quad-tree division structure, and it is provided that, upon initialization of the system, a uniform, prescribed gray scale value or picture half-tone expressed as a defined luminance value is written into the image store of a coder at the transmitter and in the image store of a decoder at the receiver store, and are in the same way for all picture elements (pixels), and both the image store in the coder as well as the image store in the decoder are each operated with feed back to themselves in a manner such that the content of the image store in the coder and decoder can be read out in blocks of variable size, and can be amplified with a factor greater than or less than 1 of the luminance and can be written back into the image store with shifted addresses, whereby the blocks of variable size are organized according to a known quad-tree data structure.

Matrix liquid crystal display with extended gray scale

Abstract: The perceived gray scale brightness levels of a Matrix Addressed Liquid Crystal Display are increased over the number of levels provided by the existing data line driver hardware and the gray scale voltage increments by providing an extra command bit position. For time multiplexing the gray scale voltage increment on a pixel during successive frames. For an extra bit value of 0 the gray scale voltage is the same during alternate frames providing a given brightness level. For an extra command bit value of 1, the gray scale voltage increment applied to the pixel and the brightness level, is switched (dithered) between voltages during successive frames. The eye integrates the levels and the perceived gray scale brightness level is the average value of brightness thus, doubling the number of perceived gray scale levels.

Fast bitonal to gray scale image scaling

Abstract: A device for re-scaling an image to change the resolution with which discrete pixel values represent it includes a scan-line interface (40) and an alignment circuit (45) that assemble sets of the original pixel values into submatrices and apply them to a convolution engine (46), which computes new pixel values from them. X and Y scaling engines (58 and 60) control the re-scaling without having to generate original-pixel address at the rate at which new pixels are generated. The X scaling engine (58) simply indicates whether an output of the currently supplied input data should be used to generate an output intensity value and, if so, whether it should be retained for generation of the subsequent intensity value, too. Similarly, the Y scaling engine (60) indicates whether the next scan line to be received should be used for generation of a scan line of output intensity values and, if so, whether it should be retained for generation of a subsequent scan line of output intensity values. In generating the new pixel values, the convolution engine (46) converts from the binary, black-and-white levels of the original pixels to gray-scale values for the new pixels to reduce the jaggedness that scale changes can cause.

Color Flow Imaging: Understanding Its Science and Technology

Abstract: The latest change to occur in diagnostic ultrasound is color flow imaging. This technology presents an image with tissue in gray scale and blood flow in color. Image formation can be asynchronous o...

Technique for optimizing grayscale character displays

Abstract: Appropriate luminance linearization values are determined for improving sub-pixel positioning of image edges in grayscale displays Individual display devices may be calibrated by and end-user, or factory luminance linearization settings may be determined Grayscale characters may be optimized for specific display devices

Image processing system and method employing combined black and white and gray scale image data

Abstract: In order to reduce data storage and transmission band­width requirements, a high resolution gray scale image is represented in two separate image forms, namely, a high resolution, high sampling density black and white image and a lower resolution, lower sampling density gray scale image. Generating separate black and white and gray scale image data allows the use of either image form independently. The high resolution black and white image data and the low resolution gray scale image data may be recombined subsequently to produce reconstructed high resolution gray scale image data representing the image.

Digital image processing technique including improved gray scale compression

Abstract: An improved technique for gray scale compression of document image data is disclosed. The method comprises evaluating subportions of an image array as to relative levels of sameness and attempting to create sub-arrays having the same pixel value. Successively smaller sub-arrays are evaluated as to gray scale sameness unti 2×1 pixel arrays are encountered. At that time a code unique to each possible 2×1 pixel arrangement is stored. A high speed, real-time compression implementation is facilitated through described hardware. Document images are subdivided into 8 pixel by 512 pixel slices. As one document slice is stored in a first buffer RAM, a previously stored slice is compressed. As the pixel information is stored, tests are performed for 8×8 and 4×4 array sameness and one bit data stored according to the results of those tests. High speed compression is facilitated by querying the stored data as to the 8×8 and the 4×4 array sameness prior to further processing. Pixel gray scale information is provided as input to look up tables which provide coded information as to gray scale value in a variable length coded output. Status of 8×8 and 4×4 blocks as to sameness controls sequencing of the input to the look up tables. The microprocessor controller handles no pixel data but merely processes coded data for placement on appropriate bus and storage in an appropriate memory medium.

Digital radiography with image brightness and contrast normalization

Abstract: A process for enhancing a still video image can correct digital fluoroscopy images which are under- or overexposed and have their image brightness values concentrated to one end of the gray scale A pixel histogram is formed, but is clipped at a low value Then, a cumulative histogram is formed from the clipped histogram The cumulative histogram, which has a generally linear slope, is normalized and is used for mapping the brightness of luminance values of the original image The new values form an optimal video image with the gray scale values spread over the entire range The image shows details not only in the middle gray areas, but in the light and dark areas as well

Digital multiple-color image processing apparatus

Abstract: An image processing apparatus includes a photoelectric converter, a multiple-value circuit, and a detachable external storage unit. The photoelectric converter photoelectrically coverts data of an original into image signals. The multiple-value circuit converts the image signals into multiple-valued data by comparing the image signals with predetermined threshold value data. The detachable external storage stores the threshold value data. The threshold values can also be made automatically responsive to gray scale data. The automatic mode and the manual selection mode are switched between in response to a release (toggle) signal. Color separation and color ghost correction are provided; and various types of formatting management are faciliated. Partial color converting (as, for example, color reversal) is also provided.

Color in computer graphic representation of two-dimensional parameter distributions

Abstract: This dissertation investigates the hypothesis that color increases the usefulness of computer graphic representations of two-dimensional parameter distributions. The motivation is provided by the desirability of presenting multidimensional multiparameter medical images in the most useful way. The approach is justified by the multiparameter nature of color and the enhanced detectability of patterns in color environments. A background of color and color models in computer graphics is presented. Several color models and the algorithms to transform between models are given. The representation of a single parameter using color is discussed. Desirable properties of color scales are stated and the most commonly used color scales are described. The notion of an optimal color scale is introduced, and the development of a particular optimal color scale is described. For this task, a new algorithm--OPTIMAL-SCALES--is introduced. The linearization of color scales is discussed and a linearization algorithm--LOS--is presented. The result of the two-step process of applying these two algorithms is presented in the form of the Linearized-Optimal Color Scale (LOCS). The representation of multiple parameters using color is discussed. A generalized lightness, hue, and saturation (GLHS) color model is proposed, which is a generalization of several of the previously presented color models and of which the existing models are special cases. They, as well as other possible models, are realized by different choices of values for parameters that characterize the general model. Transformation algorithms between the GLHS and the RGB models are given. GLHS-based color approaches for conveying multiparameter information are described. Criteria for the choice of a particular LHS special case are discussed. Uniformity is proposed as one criterion and the search for the most uniform LHS space is described. The use of color in computer graphic representation of parameter distribution is investigated with emphasis on medical applications. Several potential medical applications are discussed for both single- and multiparameter information representation. Observer performance experiments are conducted to study the merits of the proposed color methods. The results of the study show that observers performed better with a linearized gray scale than with the newly-developed LOCS at a statistically-significant level of confidence. They also show that observers performed better with the LOCS than with another color scale (the Heated-object scale), but at a non-significant level of confidence.

The Psychophysics Of Spatial Sampling

Abstract: In this paper, we study the physical and psychophysical effects of digital sampling. In particular, we study how spatial sampling (the geometry of the pixel array) and luminance sampling (the distribution of gray levels) affect the image and its perception. Taking the Thin-Film Transistor Liquid Crystal Display (TFT/LCD) as our model, we have simulated four candidate pixel geometries on a color graphics display. We have made psychophysical measurements of visual detectability, reaction time, and rated quality as a function of pixel geometry and grayscale. Our major findings are that (1) the spatial geometry of the sampling array exerts a major influence on visual performance, (2) for suprathreshold judgments of image quality, asymptotic performance is reached with as few as 2-3 bits of grayscale, and (3) the effect of grayscale on performance depends on exposure duration.

Identification information storage and retrieval.

Abstract: A method for compressing a face image (62) into a digital bit stream; the method includes the steps of converting the image (62) to an array of raw pixel values; reducing the image (62) to generate a smaller array of pixel values (72); reducing the gray scale range of the pixel values in the smaller array (74); deriving data words indicative of the pixel values (74); and encoding the data words of the bit stream in accordance with the code of the type in which more frequently occurring data words are encoded as shorter sets of bits (76).

Skeletonization And Distance Transformation By Greyscale Morphology

Abstract: Mathematical morphology applied to image processing which deals directly with shape is a more direct and faster approach to feature measurements than traditional techniques. It has grown to include many applications and architectures in image analysis. Binary morphology has been successfully extended to greyscale morphology which allows a new set of applications. In this paper, the distance transformation, skeletonization, and reconstruction algorithms using the greyscale morphology approach are described and proven to be remarkably simple. The distance transformation of an object is the minimum distance from inner points to the background of an object. The algorithm is a recursive greyscale erosion of the image with a small size structuring element. The distance can be Euclidean, chessboard, or city-block distance which depends on the selection of its structuring element. The skeleton extracted is the Medial Axis Transformation (MAT) which is produced from the result of the distance transformation. The values of the distance transform along the skeleton are maintained to represent distance to the closest boundary. We can easily reconstruct the distance transform from the skeleton by iterative greyscale dilations with the same struc-turing element. In order for this method to be useful for grey level images, a simple adaptive threshold algorithm using greyscale ero-sion with a non-linear structuring element has been developed.21 A decomposition technique which reduces the large size non-linear structuring element into a recursive operation with a small window allows real-time implementation.

Binary morphological coding of grayscale images

Abstract: One approach to image coding is to segment the original gray-scale image and then encode the boundaries and the interiors of the segments to represent the image. The authors propose a novel image coding method based on this approach, with an important difference. With the proposed coding technique, an alternative representation of the image segments is used; instead of segment boundaries, morphological skeletons are used to represent the segments. The skeleton is a thin-lined caricature of the segment that summarizes its shape and conveys information about its size, orientation, and connectivity. A binary image morphological skeletonization procedure is used to create skeletons of the image segments. In this way, the gray-scale image is represented for coding purposes by the skeletons and the intensities of the segments. Preliminary estimates show a data rate of 0.12 bits per pixel can be obtained with this coding technique. >

Data compression of gray-scale images by level plane coding

Abstract: This paper proposes a single compression coding method of gray-scale images for applications as image retrieval, etc. With this method, the psychological burden on the observer is lightened by transmitting first the approximation of the image and adding the details later. At the final stage, the exact replica of an original image can be obtained with a high compression ratio. In the coding, the image is separated first into two groups: upper bit planes relating to the most significant n bits and lower bit planes relating to the remaining bits. The pixels within the upper bit planes are encoded by subsampling and level plane coding. Subsequently, a compression coding of the pixels not yet transmitted is performed by level plane coding of the difference between the actual values and the interpolated values derived from the pixels already transmitted. Following the transmission of the upper bit plane pixels, the remaining planes of the image are transmitted bit-by-bit. To investigate the characteristics of the proposed method, computer simulations are performed by using standard SIDBA pictures. The performance of the proposed method and four other compression coding methods for grayscale images are compared. It is shown that this method achieves almost the same entropy as those of the high-efficiency coding method; the achieved average entropy is 5.21 bits/pixel.

Precise Visual Inspection Algorithm for LSI Wafer Patterns Using Grayscale Image Comparison.

Abstract: A sub-micron defect detection algorithm for LSI wafer patterns has been developed. This algorithm is based on a comparison of corresponding images of 2 chips or cells. Two grayscale images are aligned by their detected edge patterns and compared by the new algorithm called Local Perturbation Pattern Hatching, by shifting one image in 8 plane-directions and in grayscale, and finding the best match in a local window between the shifted images and the other image. The resulting unmatched regions are recognized as defects. This method is performed so as to detect 0.3 p m defects of photoresist patterns without being influenced by small irregularities of the grayscale images.

A tree grammar scheme for generation and recognition of simple texture paths in pictures

Abstract: The authors present a tree grammar scheme for generation of selected texture straight paths based on the structural and syntactic model introduced by K.S. Fu (1982). The procedure allows for representation of binary images as well as gray scale and color images. The procedure provides an easy approach for representing a quad tree and an alternative for saving space and memory access time. The authors provide a software framework which uses the concept of this grammar scheme for detection and recognition of texture paths in a gray image of N*N pixels. Prolog was chosen as the programming language, since it is easy to represent the grammar rules in this language. >

Aircraft & Cloud Sky Simulator

Abstract: A capability for generating sky images containing both clouds and aircraft has been developed through concatenating a variety of models and matting them to an Image Array Processor. A family of apparent images are generated, each at a specific wavelength, whose gray scale values are in terms of absolute radiometric units. These images can then be combined as weighted sums to represent the appropriate spectral distributions for a specific sensor of interest. For example, this simulator has been used to generate sky scenes as inputs to a color CCD camera emulation.

Method for displaying chemical shift image

Abstract: PURPOSE:To simply display a chemical shift image, by a method wherein chemical shift quantity is allowed to correspond to a color bar and the density or signal intensity in each component is allowed to correspond to brightness to synthesize the color data and brightness data to display both of them as one picture. CONSTITUTION:Chemical shift quantity is allowed to correspond to a color bar and the gray scale of the light and shade thereof is displayed in correspondence with spectrum brightness. In image data 1, a 30ppm chemical shift range is divided at about 2ppm-intervals so as to be capable of separating A, B, PD, gamma-ATP, alpha-ATP and beta-ATP to form a plurality of images and the brightness of a pixel 5' is set to that corresponding to each signal brightness. Display data 4 are collectively formed into one image like the content 6 of the display data 4. A pixel 6' is expressed at 12 bits as the brightness data obtained by synthesizing the brightnesses of a plurality of images and a color is expressed at 4 bits as a synthesized value of the colors respectively present in a plurality of the images.