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NASA NTRS1976

The imaging photopolarimeter - The first extraterrestrial spin-scan imager

The paper describes the imaging photopolarimeter used to take close-ups of Jupiter from Pioneers 10 and 11. The instrument operates in a steerable spin-scan mode of operation, contains a 1 in. diameter, f/3.4 Maksutov telescope with a focal plane aperture whose size is selectable. The paper examines those aspects of the design that are substantially influenced by the unusual design constraints, such as choice of detector and method of steering the telescope, and demonstrates the image processing and display techniques used to create the images from the telemetry and correct them for distortion and other defects.

Swindell, W.↗

NASA NTRS1980

Voyager image processing at the Image Processing Laboratory

This paper discusses new digital processing techniques as applied to the Voyager Imaging Subsystem and devised to explore atmospheric dynamics, spectral variations, and the morphology of Jupiter, Saturn and their satellites. Radiometric and geometric decalibration processes, the modulation transfer function, and processes to determine and remove photometric properties of the atmosphere and surface of Jupiter and its satellites are examined. It is exhibited that selected images can be processed into 'approach at constant longitude' time lapse movies which are useful in observing atmospheric changes of Jupiter. Photographs are included to illustrate various image processing techniques.

Jepsen, P. L.↗

NASA NTRS1981

Images of Jupiter from the Pioneer 10 and Pioneer 11 Infrared Radiometers - A comparison with visible and 5-micron images

The images with geometric control which present Pioneer 10 and 11 Infrared Radiometer data aquired at Jupiter are compared with 5.0-micron and visible images taken in the same time frame. It is found that (1) at 5.0, 20 and 45 microns, the association of dark and light areas with warm and cool areas, respectively, extends to nearly all features observed on the planet; (2) where the normal association of light and dark visible markings with the zone velocity breaks down, the infrared emission seems to follow the visible cloud structure rather than the zonal velocity structure; and (3) exceptions to the general rule involve 20-micron radiation, which reflects conditions in the 0.1-0.3 bar altitude range. A comparison of Pioneer 10 and 11 images suggests that the South Equatorial Belt became brighter at 20 microns, yet remained constant at other wavelengths between the two encounters.

Orton, G. S.↗

NASA NTRS1985

NASA image-based geological expert system development project for hyperspectral image analysis

The NASA image-based geological expert system was applied to analyze remotely sensed hyperspectral image data. The major objective is for geologists to identify the earth surface mineral properties directly from the airborne and spaceborne imaging spectrometer data. With certain constraints, it is shown that the system can identify correctly different classes of mineral. It has the built-in learning paradigm to enhance the confidence factor of mineral identification. A very powerful natural language system was incorporated as the user-friendly front end, and the concurrent processing efficiency of the frame-based knowledge representation in the hypercube microsupercomputer simulation was tested.

Chiou, W. C., Sr.↗

NASA NTRS1988

Shifting Of Image Fields For Better Stereoscopic TV Images

Concept for shifting horizontal positions of TV image fields of stereoscopic TV display reduces stereoscopic depth distorting while increasing stereoscopic depth resolution of images. Applicable to form of stereoscopic TV in which two views of scene presented by two video cameras to different fields of one monitor. According to concept, view of left camera shifts to left, and right camera, to right. Images made to overlap, so observed comfortably. Shifting done by inexpensive electronic circuitry.

Diner, Daniel B.↗

NASA NTRS1988

Streaking images that appear only in the plane of diffraction in undoped GaAs single crystals: Diffraction imaging (topography) by monochromatic synchrotron radiation

Streaking images restricted to the direction of the diffraction (scattering) vector have been observed on transmission through undoped GaAs. These disruption images (caused by the reduction of diffraction in the direction of observation) appear both in the forward and in Bragg diffracted directions in monochromatic synchrontron radiation diffraction imaging. This previously unobserved phenomenon can be explained in terms of planar defects (interfaces) or platelets which affects the absorption coefficient in anomalous transmission. Such regions of the crystal look perfect despite the presence of imperfections when the scattering vector is not perpendicular to the normal of the platelets. The observed crystallographic orientation of these interfaces strongly indicates that they are antiphase boundaries.

Kuriyama, Masao↗

NASA NTRS1988

Image processing software for imaging spectrometry data analysis

Imaging spectrometers simultaneously collect image data in hundreds of spectral channels, from the near-UV to the IR, and can thereby provide direct surface materials identification by means resembling laboratory reflectance spectroscopy. Attention is presently given to a software system, the Spectral Analysis Manager (SPAM) for the analysis of imaging spectrometer data. SPAM requires only modest computational resources and is composed of one main routine and a set of subroutine libraries. Additions and modifications are relatively easy, and special-purpose algorithms have been incorporated that are tailored to geological applications.

Mazer, Alan↗

NASA NTRS1988

Enhancement of structure images of interstellar diamond microcrystals by image processing

Image processed high resolution TEM images of diamond crystals found in oxidized acid residues of carbonaceous chondrites are presented. Two models of the origin of the diamonds are discussed. The model proposed by Lewis et al. (1987) supposes that the diamonds formed under low pressure conditions, whereas that of Blake et al (1988) suggests that the diamonds formed due to particle-particle collisions behind supernova shock waves. The TEM images of the diamond presented support the high pressure model.

O'Keefe, Michael A.↗

NASA NTRS1988

Image processing software for imaging spectrometry

The paper presents a software system, Spectral Analysis Manager (SPAM), which has been specifically designed and implemented to provide the exploratory analysis tools necessary for imaging spectrometer data, using only modest computational resources. The basic design objectives are described as well as the major algorithms designed or adapted for high-dimensional images. Included in a discussion of system implementation are interactive data display, statistical analysis, image segmentation and spectral matching, and mixture analysis.

Mazer, Alan S.↗

NASA NTRS1988

On the integration of image sources in exact image method of field analysis

Convergence conditions of image integration in the exact image method of field calculation have been investigated, and the method is extended to include more general media than previously considered. It is demonstrated that the integral is well behaved and the method works best when the field is calculated in a medium with less loss. If the medium has more loss, it is shown that the image line may enter the improper half-space and still produce valid results. Means of correctly selecting the integration path branch for the case of crossing branch cuts of the Green function in complex integration planes are proposed.

Lindell, I. V.↗

NASA NTRS1990

Fractal image analysis - Application to the topography of Oregon and synthetic images.

Digitized topography for the state of Oregon has been used to obtain maps of fractal dimension and roughness amplitude. The roughness amplitude correlates well with variations in relief and is a promising parameter for the quantitative classification of landforms. The spatial variations in fractal dimension are low and show no clear correlation with different tectonic settings. For Oregon the mean fractal dimension from a two-dimensional spectral analysis is D = 2.586, and for a one-dimensional spectral analysis the mean fractal dimension is D = 1.487, which is close to the Brown noise value D = 1.5. Synthetic two-dimensional images have also been generated for a range of D values. For D = 2.6, the synthetic image has a mean one-dimensional spectral fractal dimension D = 1.58, which is consistent with the results for Oregon. This approach can be easily applied to any digitzed image that obeys fractal statistics.

Huang, Jie↗

NASA NTRS1990

Image motion compensation for the Ultraviolet Imaging Telescope

On August 12, 1990, the Space Shuttle Columbia will carry the ASTRO-1 Spacelab payload into low earth orbit for a ten day mission. This mission will carry out ultraviolet and X-ray observations to study supernovas, galaxies, and other stellar objects. The Ultraviolet Imaging Telescope (UIT) is one of a cluster of three ultraviolet telescopes mounted on the shuttle-attached three-axis Instrument Pointing System (IPS). Shuttle disturbances such as astronaut crew motion, orbiter thruster firings, and other payload dynamic disturbances induce sufficient errors on the IPS which exceed the UIT jitter requirements. To meet the specified science objectives, an Image Motion Compensation System was designed and implemented for the ASTRO mission. This paper describes the UIT Image Motion Compensation system design and the performance improvements to be derived through use of this system.

Bauer, Frank H.↗

NASA NTRS1991

Analysis of a multiple reception model for processing images from the solid-state imaging camera

A detection model to identify the presence of Galileo optical communications from an Earth-based Transmitter (GOPEX) signal by processing multiple signal receptions extracted from the camera images is described. The model decomposes a multi-signal reception camera image into a set of images so that the location of the pixel being illuminated is known a priori and the laser can illuminate only one pixel at each reception instance. Numerical results show that if effects on the pointing error due to atmospheric refraction can be controlled to between 20 to 30 microrad, the beam divergence of the GOPEX laser should be adjusted to be between 30 to 40 microrad when the spacecraft is 30 million km away from Earth. Furthermore, increasing beyond 5 the number of receptions for processing will not produce a significant detection probability advantage.

Yan, T.-Y.↗

NASA NTRS1991

Techniques for removing non-uniform background in coded-aperture imaging on the energetic X-ray imaging telescope experiment

It is found that the subtractive flat field technique for nonuniform background illumination is generally effective at removing background systematics for stationary mask experiments such as the Energetic X-ray Imaging Experiment. The time dependence of intensity and the two-dimensional shape of the background detector image during the flight are explored. A flat field image is constructed from observations where X-ray sources were absent from the field of view. It is shown that this technique can successfully reduce rms fluctuations to within a few percent of ideal Poisson statistics. The quality of the flat field does not appear to be a strong function of radius and can be used effectively out to the edge of the detector to remove the strong background ring.

Covault, C. E.↗

NASA NTRS1991

Flight performance of a Shuttle-based image motion compensation system for the Ultraviolet Imaging Telescope

The design of the Ultraviolet Imaging Telescope (UIT) Image Motion Compensation System developed for the Columbia's Astro-1 mission is described, and the performance improvements derived through the use of this system are discussed. Flight data are presented, demonstrating the superb image stability achieved by UIT resulting in outstanding scientific data returns.

Deily, John J.↗

NASA NTRS1991

Gain calibrating nonuniform image-array data using only the image data

An algorithm is developed for calibrating the spatial nonuniformity of image-array (CCD-type) detectors. Like other techniques this approach uses multiple, spatially displaced images. In circumstances where high-precision flat fields are not available by other means (i.e., sky flats) this technique is advantageous as it uses the data frames for gain calibration even when the array images extended, nonuniform, sources. Numerical experiments and direct observations with intrinsically uniform and quite nonuniform detectors show that this algorithm is useful when data frames are crowded with sources - circumstance where 'median filtering' flatfielding techniques often fail. The algorithm described is robust and efficiently uses information from multiple data frames to determine pixel gain variations, using visible and IR array observations of extended sources.

Kuhn, J. R.↗

NASA NTRS1993

Registration Of SAR Images With Multisensor Images

Semiautomated technique intended primarily to facilitate registration of polarimetric synthetic-aperture-radar (SAR) images with other images of same or partly overlapping terrain while preserving polarization information conveyed by SAR data. Technique generally applicable in sense one or both of images to be registered with each other generated by polarimetric or nonpolarimetric SAR, infrared radiometry, conventional photography, or any other applicable sensing method.

Evans, Diane L.↗

NASA NTRS1992

Ultraviolet Imaging Telescope ultraviolet images - Large-scale structure, H II regions, and extinction in M81

The study employs UV images of M81 obtained by the Ultraviolet Imaging Telescope (UIT) during the December 1990 Astro-1 spacelab mission to determine 2490- and 1520-A fluxes from 46 H II regions and global surface brightness profiles. Comparison photometry in the V band is obtained from a ground-based CCD image. UV radial profiles show bulge and exponential disk components, with a local decrease in disk surface brightness inside the inner Lindblad Resonance about 4 arcmin from the nucleus. The V profile shows typical bulge plus exponential disk structure, with no local maximum in the disk. There is little change of UV color across the disk, although there is a strong gradient in the bulge. Observed m152-V colors of the H II regions are consistent with model spectra for young clusters, after dereddening using Av determined from m249-V and the Galactic extinction curve. The value of Av, so determined, is 0.4 mag greater on the average than Av derived from radio continuum and H-alpha fluxes.

Hill, Jesse K.↗