Showing papers on "Image processing published in 1981"

Random sample consensus: a paradigm for model fitting with applications to image analysis and automated cartography

Abstract: A new paradigm, Random Sample Consensus (RANSAC), for fitting a model to experimental data is introduced. RANSAC is capable of interpreting/smoothing data containing a significant percentage of gross errors, and is thus ideally suited for applications in automated image analysis where interpretation is based on the data provided by error-prone feature detectors. A major portion of this paper describes the application of RANSAC to the Location Determination Problem (LDP): Given an image depicting a set of landmarks with known locations, determine that point in space from which the image was obtained. In response to a RANSAC requirement, new results are derived on the minimum number of landmarks needed to obtain a solution, and algorithms are presented for computing these minimum-landmark solutions in closed form. These results provide the basis for an automatic system that can solve the LDP under difficult viewing

Displacement Measurement and Its Application in Interframe Image Coding

Abstract: A new technique for estimating interframe displacement of small blocks with minimum mean square error is presented. An efficient algorithm for searching the direction of displacement has been described. The results of applying the technique to two sets of images are presented which show 8-10 dB improvement in interframe variance reduction due to motion compensation. The motion compensation is applied for analysis and design of a hybrid coding scheme and the results show a factor of two gain at low bit rates.

Image data compression: A review

Abstract: With the continuing growth of modern communications technology, demand for image transmission and storage is increasing rapidly. Advances in computer technology for mass storage and digital processing have paved the way for implementing advanced data compression techniques to improve the efficiency of transmission and storage of images. In this paper a large variety of algorithms for image data compression are considered. Starting with simple techniques of sampling and pulse code modulation (PCM), state of the art algorithms for two-dimensional data transmission are reviewed. Topics covered include differential PCM (DPCM) and predictive coding, transform coding, hybrid coding, interframe coding, adaptive techniques, and applications. Effects of channel errors and other miscellaneous related topics are also considered. While most of the examples and image models have been specialized for visual images, the techniques discussed here could be easily adapted more generally for multidimensional data compression. Our emphasis here is on fundamentals of the various techniques. A comprehensive bibliography with comments is included for a reader interested in further details of the theoretical and experimental results discussed here.

Advances in mathematical models for image processing

Abstract: Several state-of-the-art mathematical models useful in image processing are considered. These models include the traditional fast unitary transforms, autoregessive and state variable models as well as two-dimensional linear prediction models. These models introduced earlier [51], [52] as low-order finite difference approximations of partial differential equations are generalized and extended to higher order in the framework of linear prediction theory. Applications in several image Processing problems, including image restoration, smoothing, enhancement, data compression, spectral estimation, and filter design, are discussed and examples given.

Estimating three-dimensional motion parameters of a rigid planar patch

Abstract: We present a new direct method of estimating the three-dimensional motion parameters of a rigid planar patch from two time-sequential perspective views (image frames). First, a set of eight pure parameters are defined. These parameters can be determined uniquely from the two given image frames by solving a set of linear equations. Then, the actual motion parameters are determined from these pure parameters by a method which requires the solution of a sixth-order polynomial of one variable only, and there exists a certain efficient algorithm for solving a sixth-order polynomial. Aside from a scale factor for the translation parameters, the number of real solutions never exceeds two. In the special case of three-dimensional translation, the motion parameters can be expressed directly as some simple functions of the eight pure parameters. Thus, only a few arithmetic operations are needed.

Depth from edge and intensity based stereo

Abstract: The past few years have seen a growing interest in the application" of three-dimensional image processing. With the increasing demand for 3-D spatial information for tasks of passive navigation [7,12], automatic surveillance [9], aerial cartography [10,13], and inspection in industrial automation, the importance of effective stereo analysis has been made quite clear. A particular challenge is to provide reliable and accurate depth data for input to object or terrain modelling systems (such as [5]. This paper describes an algorithm for such stereo sensing It uses an edge-based line-by-line stereo correlation scheme, and appears to be fast, robust, and parallel implementable. The processing consists of extracting edge descriptions for a stereo pair of images, linking these edges to their nearest neighbors to obtain the edge connectivity structure, correlating the edge descriptions on the basis of local edge properties, then cooperatively removmg those edge correspondences determined to be in error - those which violate the connectivity structure of the two images. A further correlation process, using a technique similar to that used for the edges, is applied to the image intensity values over intervals defined by the previous correlation The result of the processing is a full image array disparity map of the scene viewed.

Scene adaptive coder

Abstract: An efficient single-pass adaptive bandwidth compression technique using the discrete cosine transform is described. The coding process involves a simple thresholding and normalization operation on the transform coefficients. Adaptivity is achieved by using a rate buffer for channel rate equalization. The buffer status and input rate are monitored to generate a feedback normalization factor. Excellent results are demonstrated for coding of color images at 0.4 bits/pixel corresponding to real-time color television transmission over a 1.5 Mbit/s channel.

Wedge-and-strip anodes for centroid-finding position-sensitive photon and particle detectors.

Abstract: The paper examines geometries employing position-dependent charge partitioning to obtain a two-dimensional position signal from each detected photon or particle. Requiring three or four anode electrodes and signal paths, images have little distortion and resolution is not limited by thermal noise. An analysis of the geometrical image nonlinearity between event centroid location and the charge partition ratios is presented. In addition, fabrication and testing of two wedge-and-strip anode systems are discussed. Images obtained with EUV radiation and microchannel plates verify the predicted performance, with further resolution improvements achieved by adopting low noise signal circuitry. Also discussed are the designs of practical X-ray, EUV, and charged particle image systems.

A Survey of Electronic Techniques for Pictorial Image Reproduction

Abstract: This paper is a tradeoff study of image processing algorithms that can be used to transform continuous tone and halftone pictorial image input into spatially encoded representations compatible with binary output processes. A large percentage of the electronic output marking processes utilize a binary mode of operation. The history and rationale for this are reviewed and thus the economic justification for the tradeoff is presented. A set of image quality and processing complexity metrics are then defined. Next, a set of algorithms including fixed and adaptive thresholding, orthographic pictorial fonts, electronic screening, ordered dither, and error diffusion are defined and evaluated relative to their ability to reproduce continuous tone input. Finally, these algorithms, along with random nucleated halftoning, the alias reducing image enhancement system (ARIES), and a new algorithm, selective halftone rescreening (SHARE), are defined and evaluated as to their ability to reproduce halftone pictorial input.

PASM: A Partitionable SIMD/MIMD System for Image Processing and Pattern Recognition

Abstract: PASM, a large-scale multimicroprocessor system being designed at Purdue University for image processing and pattern recognition, is described. This system can be dynamically reconfigured to operate as one or more independent SIMD and/or MIMD machines. PASM consists of a parallel computation unit, which contains N processors, N memories, and an interconnection network; Q microcontrollers, each of which controls N/Q processors; N/Q parallel secondary storage devices; a distributed memory management system; and a system control unit, to coordinate the other system components. Possible values for N and Q are 1024 and 16, respectively. The control schemes and memory management in PASM are explored. Examples of how PASM can be used to perform image processing tasks are given.

Uniformly redundant arrays: digital reconstruction methods

Abstract: Several new digital reconstruction techniques for coded aperture imaging are developed which are especially applicable to uniformly redundant arrays (URAs). The techniques provide improved resolution without upsetting the artifact-free nature of URAs. Two new techniques are described; one which allows self-supporting URAs and one which avoids (or at least mitigates) a blur which has been associated with previous correlation analyses. Each of the methods and their resolution improvements are demonstrated with reconstructions of a laser-driven compression. Particular emphasis has been placed on the special sampling required of the encoded picture and the decoding function if artifacts are to be avoided. For large URAs, it is shown that another new digital technique, periodic decoding, is much faster. Periodic decoding does produce artifacts, but they usually are negligible.

The role of human visual models in image processing

Abstract: The mechanisms are discussed by which the human eye forms a neural image of the outside world for transmission along the optic nerve. Mathematical models of these mechanisms which can be exploited for engineering purposes are presented and their usefulness and limitatious are discussed. Three areas in which human vision models have been successfully applied are image bandwidth compression, image quality assessment, and image enhancement; results from these areas are summarized and some example results are given. Some future directions are suggested.

Acousto-optic signal processing: Convolution and correlation

Abstract: The use of acousto-optic devices in real-time signal convolution and correlation has increased dramatically during the past decade because of improvements in device characteristics and implementation techniques. Depending on the application, processing can be implemented via spatial or temporal integration. Two-dimensional signal processing (including image processing) is possile, in spite of the inherent one-dimensional nature of the acousto-optic device as a spatial light modulator.

Algorithms for Fast Back- and Re-Projection in Computed Tomography

Abstract: While the computation time for reconstructing images in C.T. is not a problem in commercial systems, there are many experimental and developmental applications where resources are limited and image reconstruction places a heavy burden on the computer system. This paper describes a very efficient back-projection algorithm which results in large time savings when implemented in machine code. Also described is a minor modification to this algorithm which converts it to a re-projection procedure with comparable efficiency.

Computer Architectures for Pictorial Information Systems

Abstract: In the international search for the optimal image processing computer architecture, image parallelism is the key to cost effectiveness.

The Multistage Cube: A Versatile Interconnection Network

Abstract: The cube network can support both MIMD and SIMD processing in distributed systems. It allows flexible communications in systems like PASM, PUMPS, and the BMD test bed.

An Algorithm for Converting Rasters to Quadtrees

Abstract: An algorithm is presented for constructing a quadtree for a binary image given its row-by-row description. The algorithm processes the image one row at a time and merges identically colored sons as soon as possible, so that a minimal size quadtree exists after processing each pixel. This method is spacewise superior to one which reads in an entire array and then attempts to build the quadtree.

Tomographic image reconstruction from limited projections using iterative revisions in image and transform spaces

Abstract: An iterative technique is proposed for improving the quality of reconstructions from projections when the number of projections is small or the angular range of projections is limited. The technique consists of transforming repeatedly between image and transform spaces and applying a priori object information at each iteration. The approach is a generalization of the Gerchberg-Papoulis algorithm, a technique for extrapolating in the Fourier domain by imposing a space-limiting constraint on the object in the spatial domain. A priori object data that may be applied, in addition to truncating the image beyond the known boundaries of the object, include limiting the maximum range of variation of the physical parameter being imaged. The results of computer simulations show clearly how the process of forcing the image to conform to a priori object data reduces artifacts arising from limited data available in the Fourier domain.

Three-dimensional digital topology

Abstract: Basic concepts of connectedness, cavities, and holes are defined for subsets of three-dimensional arrays. Three-dimensional arcs and curves are also defined and characterized.

Interactive video production system

Abstract: An improved interactive image processing system (200,300) is provided which is capable of simultaneous processing of at least two different digitized composite color images to provide a displayable resultant composite color image. Each of the digitized composite color images have separate digitized red, blue and green image components and have an associated image information content. The system (200,300) includes separate image storage planes (246,346,70',72',74',70",72",74",70"',72'", 74"',370,372,374,370',372',374',370",372",374) for retrievably storing each of the digitized red, blue and green image components or other image data as well as graphic planes (78',378) for storing graphic control data for processing of the images. The digital image processing of the image components is accomplished in a digital image processing portion (208,308) which includes an image processor (210,310) which contains the various storage planes in a refresh memory (246,346) which cooperates with a pipeline processor configuration (86'), image combine circuitry (270,272,274,270',272',274') and other control circuitry to enable the simultaneous processing between each of the corresponding image planes on a pixel by pixel basis under interactive control of a keyboard (50'), data tablet (54') or other interactive device. The system may be employed for interactive video processing (200) or as an interactive film printing system (300) in which the simultaneous processing of the two different images, which may be iterative, can be monitored in real time on a television monitor (44',315). In the video system (200), the combining format of the image planes may be interactively varied on a pixel-by-pixel basis by creating different digital control masks for each pixel which are stored in refresh memory (246,346). In either system (200,300), the interactive simultaneous digital processing of the images is accomplished in an RGB format.

A VLSI architecture for updating raster-scan displays

Abstract: Interactive use of a display requires the capability to update the display rapidly. This paper describes an on-going project at Carnegie-Mellon University in which we are designing a frame buffer raster-scan display system which has the high performance typically required for interactive display applications. The system is intended to be a display for personal computers, computer generated graphic images, and image processing applications. Built using smart VLSI memory chips, the system will use parallel processing techniques to provide high performance.