A general purpose knowledge-based system for biomedical image interpretation is presented. The system acquires knowledge directly from the experts by means of a user friendly dialogue. The knowledge introduced tailors the system to a particular biomedical application. Frame representation technique is used for the representation of descriptive knowledge and a fuzzy reasoning strategy, based on fuzzy production rules, is adopted to manipulate the certain and uncertain knowledge contained into Frame Slots and to deduce interpretations. A detailed description of the application of the system to the analysis of CT images of vertebrae for the quantity evaluation of the bone mineral content is provided.

We focus on the definition of an effective strategy that allows the user to pose a visual query and retrieve a set of images from a database that satisfy his criteria of pictorial similarity without requiring any semantic expression of them. The strategy exploits a multiresolution wavelet transform to effectively describe image content. The salient features of the images are coded in signatures of predefined lengths which are compared in the retrieval phase by applying a similarity measure the system has pre-learned, using a regression model for ordinal responses, from a learning set of "very similar", "rather-similar", "not-very-similar", and "different" pairs of images. Some experimental results demonstrating the effectiveness of this approach are reported.

In spite of the widespread use of color for coding information, many aspects of color itself and of its use are unknown to both users and system designers. A color coding system based on the fundamental principles of human vision is described here. The system prevents the user from making mistakes in coding, while guaranteeing the possibility of reproducing them on different devices. It allows users to generate unordered or ordered color sets (color scales) for data representation on both screen and paper in a simple and intuitive way. Examples of its application are drawn from remote sensing data analysis. As the basic principles are quite general, applications of a different nature can be easily provided for.

In image analysis, the concept of similarity has been widely explored and various measures of similarity, or of distance, have been proposed that yield a quantitative evaluation. There are cases, however, in which the evaluation of similarity should reproduce the judgment of a human observer based mainly on qualitative and, possibly, subjective appraisal of perceptual features. This process is best modeled as a cognitive process based on knowledge structures and inference strategies, able to incorporate the human reasoning mechanisms and to handle their inherent uncertainties. This article proposes a general strategy for similarity evaluation in image analysis considered as a cognitive process. A salient aspect is the use of fuzzy logic propositions to represent knowledge structures, and fuzzy reasoning to model inference mechanisms. Specific similarity evaluation procedures are presented that demonstrate how the same general strategy can be applied to different image analysis problems. (C) 1993 John Wiley & Sons, Inc.

The purpose of this paper is to describe a procedure for the automatic selection of control-points in remote-sensing images of high-relief terrains for alignment with a reference map. This problem has been found to be of strategic importance whenever remote sensing images have to be integrated in a Geographic Information System (GIS) and processed in real time. The procedure described here is based on the recognition of shadow structures in the satellite image and on their comparison with the computer-generated shadows obtained from the Digital Terrain Model (DTM) of the region. The procedure was developed for a Landsat TM image of the Aurina Valley (in the Pusteresi Alps) with the DTM obtained from an IGM (Istituto Geografico Militare) 1:25 000 reference map, but with minor changes it can be extended to other remote-sensing images. Comparison of the shadow structures is performed by similarity evaluation of a simplified model of their shapes described by means of inertia ellipses. Each pair of shadow structures, recognized as similar and meeting a number of positional constraints, yields a pair of corresponding points whose coordinates provide input values for determining the parameters in the transformation of the input image into a planimetrically corrected one. The performance and robustness of the method and its boundary applicability are assessed. An example is given in which the automatically-determined control-points are directly inserted in a warping function, with reasonably good results.

In an increasing number of computer-graphics applications, the user makes critical color decisions on-screen. This leads to a growing demand for user-interfaces that allow color specification in a natural and effective way. This paper presents a visual language for communicating colors by appearance between the user and the computer system. The basic operations of selecting and editing colors are performed by pointing on the screen to samples of the current color space taken at variable sampling intervals, thus making possible both coarse and fine specification. Rigorous device-modeling tools provide hardware independence and reproducibility on various output devices. The software was implemented on the top of the XII Window Systern on a general-purpose graphic work station.

The development of an interactive system tailored to support the activity of the geologist, who examines the gravimetric map of a region to draw information about the geological underground structures, is described. Access to the system is managed by an interface that creates a visual environment for the expert engaged in designing and testing procedures that automatically may execute the activity of interpreting gravimetric maps. The gravimetric map is a suitable representation of a digital image whose pixel values are related to gravimetric measures

The black hole candidate Cygnus X-1 was observed in the hard X ray - soft γ ray energy range by the MISO telescope on two different occasions: in September 1979 and May 1980. We have measured two hard X-ray states of the source: in 1979 the observed spectrum confirms the superlow state measured in the same period by the HEAO-3 satellite, while in 1980 the MISO X-ray data are consistent with the so called low state of Cygnus X-1. In both occasions, no γ -ray excess has been observed above 200 KeV.

view Abstract Citations (14) References (36) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Broad-Band Contemporaneous Study of the Seyfert Galaxy NGC 4151 Bassani, L. ; Butler, R. C. ; Di Cocco, G. ; Della Ventura, A. ; Perotti, F. ; Villa, G. ; Baker, R. E. ; Dean, A. J. ; Lee, T. J. Abstract The authors observed the Seyfert galaxy NGC 4151 on 1980 May 18 at hard X-ray/low gamma-ray energies using the MISO telescope. No gamma-ray signal was found between 100 keV and 16 MeV and only a 3.5 σ signal was detected in the hard X-ray detector in the energy range 35 - 105 keV. Concurrently with this measurement, a program of ultraviolet and infrared observations was organized. Contemporaneous observations are also available in the optical and soft X-ray (2 - 10 keV) spectral regions. These observations are used to discuss the spectrum and the variability of NGC 4151 over a wide range of frequencies. Publication: The Astrophysical Journal Pub Date: December 1986 DOI: 10.1086/164802 Bibcode: 1986ApJ...311..623B Keywords: Astronomical Spectroscopy; Gamma Ray Spectra; Infrared Spectra; Seyfert Galaxies; Ultraviolet Spectra; X Ray Spectra; Luminosity; Radiant Flux Density; Visible Spectrum; Astrophysics; GALAXIES: INDIVIDUAL NGC NUMBER: NGC 4151; GALAXIES: SEYFERT; GAMMA RAYS: GENERAL; INFRARED: SOURCES; ULTRAVIOLET: SPECTRA; X-RAYS: SOURCES full text sources ADS | data products SIMBAD (1) NED (1) MAST (1) INES (1)

In this paper a method for the use of remote sensing to improve simulation of snow cover evolution by a digital model is examined. This method has been applied to the Alto Piave River basin, for which a snow cover evolution model has already been constructed, and uses a digital topographic model based on a grid of the same dimensions as the Landsat pixels. The remote sensing images have been enhanced with an automatic technique, thus obtaining a three level classification: snow- covered soil, non-snow-covered soil, and transition zone. A further selection on the basis of elevation assigns indeterminate pixels to one of the other two classes. The snow cover height of each pixel is computed by regression analysis and hence the statistics of elevation classes vs. snow-cover height classes are obtained.

The MISO telescope is a gamma-ray detector operating in the (0.1÷20) MeV energy range. This instrument was flown success-fully from Palestine, Texas (U.S.A.) in May 1977, October 1978, September 1979 and May 1980. During the four flights, the telescope observed a number of galactic and extragalactic sources. The Crab Nebula was detected in 1980 and its spectrum was measured up to 2 MeV. Cygnus X-1 was observed in 1979 and 1980 and was found to be in different hard X-ray states on each occasion: in a superlow state in 1979 and in a low state in 1980. The COS-B high-energy (E>50 MeV) gamma-ray sources CG 135+1 (1978) and CG 195+4 (1978) were also observed by the same instrument. From the region containing CG 135+1 a 5σ excess was measured in the counting rate of the telescope above 120 keV. No statistically significant low-energy gamma-ray flux was detected from CG 195+4. The Seyfert galaxies NCG 4151 (1977, 1979, 1980), and MCG 8-11-11 (1979), the BL LAC object MK 501 (1979) and the «peculiar» galaxy NGC 1275 (1979) were also searched for gamma-ray emission. The data on NGC 4151 and MCG 8-11-11 are consistent with power law spectra having photon indices α∼1 in the (0.1÷3) MeV energy range. Above this energy, the MISO and SAS-2/COS-B measurements require spectral breaks to α≥3. Upper limits were obtained on the emission from both MK 501 and NGC 1275.

A multitemporal analysis on the Mount Disgrazia glaciers was performed by using the 1975, 1978 and 1980 MSS Landsat images. On these images the glaciers were completely described in their boundaries and surface features. Fixed structures were used along their boundaries as fiducial points of the ground control table for the multitemporal comparison of the glaciers. This makes it possible to estimate the glacier surface changes due to frontal displacements as well as the changes, in the snow-covered area due to the displacements of the snow transient line. The procedure is possible since the recordings of Landsat satellites are continuous in space and time. It gives completeness to the individual data on the glaciers as provided by the field measurements and it makes the management of the water resources possible.

During a balloon flight in September 1979 of the MISO low-energy γ-ray telescope, the BL Lac-object MkN 501 was studied in the hard X-ray range above 30 keV and in the low energy γ-ray range up to 19 MeV. No statistically significant X- and γ-ray fluxes were detected. The implications of the upper limits obtained are discussed in the light of the relativistic jet theories recently proposed.

During a balloon flight of the MISO telescope on 1980 May 17, the Crab Nebula and the Seyfert galaxy NGC 4151 were studied over the photon energy range 0.03 –16 MeV. The photon spectrum of the Crab Nebula was measured up to ∼ 2 MeV. No gamma-ray emission from NGC 4151 was detected on this occasion.

The galaxy MCG8 –11 –11 inside the 0.093 square degrees error-box of the X-ray source 2A0551 + 466 (ref. 1), was recently found to be a Type 1 Seyfert galaxy2. A 40-arcs error-box from the A3 experiment on HEAO1 has confined the X-ray emission to the nucleus or bar of this 14-mv galaxy3. The redshift is z = 0.0205 (ref. 2), corresponding to a distance of 123 Mpc (H0 = 50 km s−1 Mpc−1). The 2–10 keV luminosity ranges from 5 × 1043erg s−1 to 1.2 × 1044erg s−1 (refs 1,3). Hard X-ray emission above 20 keV from the region of MCG8 –11 ‐11 has been recently reported4, and the A2 experiment on HEAO 1 has provided for the first time the emission spectrum of this object up to 30 keV (ref. 5). During a balloon flight on 30 September 1979 from Palestine, Texas of the Milan/Southampton (MISO) low-energy γ-ray telescope, an excess at the 3.9σ level in the flux above 90 keV was detected from a region of the sky containing MCG8 –11 –11. The emission spectrum, evaluated in the energy range 0.02–19 MeV, has similar spectral characteristics to those observed with the same telescope and associated with the Seyfert galaxy NGC4151 (ref. 6). Both spectra show evidence for a high-energy cutoff close to 3 MeV and this feature could be interpreted on the basis of the ‘Penrose–Compton scattering’ process7. A large amount of the observed low-energy γ-ray diffuse background8 could be produced by a few per cent of the X-ray emitting Seyfert galaxies having a γ-ray luminosity comparable with that observed from the region of NGC4151 or MCG8 –11 –11.

view Abstract Citations (46) References (13) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Low-energy gamma-ray emission close to CG 135+1. Perotti, F. ; della Ventura, A. ; Villa, G. ; Di Cocco, G. ; Butler, R. C. ; Dean, A. J. ; Hayles, R. I. Abstract A region of the sky close to the COS B source CG 135 + 1 was studied over the photon energy range 20 keV-25 MeV from balloon altitudes on 1978 October 8. A five-standard-deviation excess was measured in the counting rate of the telescope above 120 keV, and the spectrum of the source was evaluated. Publication: The Astrophysical Journal Pub Date: July 1980 DOI: 10.1086/183289 Bibcode: 1980ApJ...239L..49P Keywords: Cos-B Satellite; Gamma Ray Astronomy; Photon Density; Quasars; Astronomical Coordinates; Balloon Flight; Radio Sources (Astronomy); Standard Deviation; Telescopes; X Ray Sources; Astrophysics full text sources ADS | data products SIMBAD (4)