Showing papers in "Computer Graphics and Image Processing in 1979"

TL;DR: A relationship between the time variation of intensity, the spatial gradient, and velocity has been developed which allows the determination of motion using clustering techniques, and the clustering technique is described.

TL;DR: In this article, a new smoothing algorithm is proposed, which looks for the most homogeneous neighborhood area around each point in a picture, and then gives each point the average gray level of the selected neighborhood area.

TL;DR: In this paper, the authors proposed a method for fitting conic sections to scattered data, which permits an extension to conic splines around extended digitized curves, expediting a smooth reconstruction of their curvature.

TL;DR: Methods of hidden surface removal and shading for computer-displayed surfaces if the surface to be displayed is approximated by a large number of square faces of restricted orientation work at least an order of magnitude faster than previously published methods.

TL;DR: The co-occurrence matrix is used for segmentation according to texture and is evaluated on a set of regions forming two levels of the quadratic picture tree (or pyramid) if the matrices of a region and its four children in the tree are similar.

TL;DR: An iterative algorithm, MENT, which produces a maximum entropy solution to the problem of reconstructing a source from a discrete set of projection data, and is compared with regard to convergence rates, artifact formation, and stability against noise errors in the data.

TL;DR: Methods are presented for obtaining the required information directly from the statistics of the sensor outputs for destriping of LANDSAT Multispectral Scanner images, applying to images obtained with any multisensor line-scan camera.

TL;DR: Experimental results show that this system is quite useful in analyzing aerial photographs of complex suburban areas, and the properties of the recognized objects are used in analysis of the rest of the picture which was left unrecognized at the first step of recognition.

TL;DR: In this paper, a picture digitization grid based on logarithmic spirals rather than Cartesian coordinates is presented, which yields many geometric observations useful for computer graphics and picture processing.

TL;DR: In this paper, a line-drawing method for quadric surfaces is described. Butler et al. used matrix algebra and parametric equations to compute intersections of two or three quadric surface surfaces.

TL;DR: A scheme for extracting the images of moving objects in dynamic scenes using Differencing operations to identify areas containing moving objects and focusing the segmentation processes on these restricted areas.

TL;DR: In this article, the authors present a discrete version of the medial involution algorithm, suited to polygons of small exterior angles and a rather high number of sides, which provides a fast approximation to the sym-ax of differentiable curves near to the polygon.

TL;DR: A general method for designing networks of locally interconnected simple processors that include the network of interconnections among the participating processors, as well as the iterative computation to be performed by each processor is described.

TL;DR: In this article, the isovist fields are defined by associating a scalar measure of Vx at each point x in a space P, Vz is the subset of P visible from x.

TL;DR: Scenes consisting of spatially compact regions which contrast with their surrounds can be segmented by extracting connected components of above-threshold values whose borders match the positions of edges, illustrating how the redundancy of different information sources aids segmentation.

TL;DR: Two algorithms for filling irregular polygons are presented, both oriented towards raster graphics devices and use the refresh memory for part of their working space, and they can easily be adapted for shading according to any preassigned rule.

TL;DR: This paper gives a mathematical analysis of the error in alignment of the graticule, leading to a simple quantitative estimate of this error in terms of the displacement, and shows further that the displacement can be indirectly measured by using a pin phantom.

TL;DR: It is shown that the impulse response for the composite of the projection and back-projection operators for fan-beam geometry is not spatially invariant if the data are taken over 180° as is true for parallel-beam projection data.

TL;DR: A scan line method is presented for creating shaded pictures of parametrically defined curved surfaces of piecewise continuity class C2 that results in smoothly curved silhouettes.

TL;DR: A class of feature-detection operations using orthonormal basis functions is introduced in this paper, where the basis functions are derived from the Karhunen-Loeve expansion of the local image data.

TL;DR: In this article, formal properties of discrete circles (defined as Freeman digitizations of circles with integer radius and center coordinates), discrete disks, defined as discrete circles with filled-in interiors, and discrete rings are derived, including conditions for occurrence of certain point configurations, formulas for the number of raster points in these objects and their perimeters and areas.

TL;DR: The efficiencies of the various coding schemes are examined and the 4-way code is found to be the most efficient of the close-neighbors coding schemes, although efficiency can be further increased by use of a generalized code.

TL;DR: Some geometric processes giving rise to patterns that may be useful for image modelling are described and several statistics are suggested for modelling purposes.

TL;DR: Three methods based on pyramid data structures are presented for transmitting rough approximations of images before the details, thereby providing immediate feedback to the user of interactive raster graphics over a low-bandwidth transmission line.

TL;DR: The transformation algorithm is shown to take time O(n + sp + mg) , where n is the number of nodes in the input tree, s is a scale factor, p is the total perimeter of all the regions of the original picture, m is theNumber of regions, and q is a resolution parameter.

TL;DR: In this paper, a new method for coding and segmentation of binary pictures is presented, which is related to the common chain-code, but the coder works in raster scan mode, and therefore no intermediate storage for the image is needed in connection with Raster scan devices.

TL;DR: A texture grammar inference procedure which employs a clustering algorithm and a stochastic regular grammar inference Procedure and is introduced.

TL;DR: In this paper, a method that includes diffraction effects is introduced for the tomographic reconstruction of the ultrasonic velocity distribution of an object in the spatial frequency domain and is based on two perturbation approximations to the wave equation.

TL;DR: In this article, a comparison of the accuracy and reliability of a number of directional edge operators is made, and the Hueckel operator is singled out for comment, and an error in its derivation is noted.