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At least 685 records · Page 38

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NASA NTRS1985

Radiometric comparison of two ocean color scanners Nimbus-7/CZCS and OSTA-1/OCE

On November 14, 1981 the area around the Gibraltar Strait was observed by two different ocean color scanners: a Space Shuttle-borne Ocean Color Experiment and Coastal Zone Color Scanner (Nimbus-7/CZCS). This presented an opportunity to study the gradual degradation of the CZCS sensitivity by comparing the two sensors. Upwelling radiances from eleven targets were compared. The results of the analysis indicate that the CZCS sensitivities at channels 1 and 2 are down to 65 percent and 78 percent. However, the evidence for channels 3 and 4 deterioration could not be found.

Kim, H. H.↗

NASA NTRS1985

Outer solar system materials - Ices and color systematics

Our program of VJHK colorimetric observations and spectrophotometry is reviewed and updated. Attention is given to the probable connections between VJHK colors and the ratios of bright ices and dark soils on many outer solar system small bodies' surfaces. VJHK color systematics may clarify ice/soil behaviors in bodies too faint for high resolution spectra. Comets appear colored by soils most closely resembling D-class Trojan asteroid soils. Our recent model of comet surface properties, involving weakly-bonded ice/soil regoliths, helps explain comet eruptive phenomena. The work suggests the importance of considering ices in the context of their intimate mixture with non-volatile soils.

Hartmann, W. K.↗

NASA NTRS1986

Active-passive airborne ocean color measurement. I - Instrumentation

The instrumentation used in a multichannel lidar fluorosensor spectrometer functioning concurrently as a passive spectroradiometer for measuring upwelling ocean color radiance is discussed. The instrument calibration techniques are addressed, including the absolute passive calibration technique, the importance of relative channel-to-channel calibration for accurate ocean color measurement, and active mode calibration techniques using passive calibration transfer methods. Ground and flight test results from the dual-mode active-passive ocean color sensor are discussed.

Hoge, F. E.↗

NASA NTRS1986

The color of meteoritic hibonite - An indicator of oxygen fugacity

Hibonites similar in composition to those found in Ca-Al-rich inclusions change color from blue, to green, to orange, to nearly colorless as oxygen fugacity is increased at high temperature from below the iron-wustite buffer up to air. The development of the blue color is correlated with the growth of an absorption band at 715 nm in the optical spectra of the hibonites as the oxygen fugacity is reduced. The growth of this band is attributed to the increasing concentration of Ti(3+) in these hibonites with decreasing oxygen fugacity. The blue hibonites in meteorites reflect equilibration under reducing conditions based on the intensity of 715 nm band, it is estimated that the hibonite in the Blue Angel inclusion indicates an oxygen fugacity four to five orders of magnitude more oxidizing than that expected in the early solar nebula. This may be due to formation in an anomalously oxidizing region of the nebula or to oxidation during cooling or later alteration. The orange hibonites in Allende reflect oxygen fugacities approximately ten or more orders of magnitude more oxidizing than the expected primitive nebula; this color probably indicates alteration of initially more reduced (blue?) hibonites. The colorless hibonite in the HAL inclusion reflects highly oxidizing conditions and/or its low Ti content.

Ihinger, P. D.↗

NASA NTRS1985

Color contouring for atmospheric data sets

A program has been developed for use by researchers at the Langley Research Center (LaRC) to allow a quick and easy method to display color contour plots. The bilinear interpolation technique used in the contouring routine enables the user to analyze large data sets with smoothly varying color changes instead of dashes and lines. Annotations can be added to enhance the contour plot, and the resulting plot can easily be made into a color print or a viewgraph.

Ferebee, M. T.↗

NASA NTRS1987

Reducing Color/Brightness Interaction in Color Television

Proposed digitally sampled scan-conversion scheme for color television reduces unwanted interactions between chrominance and luminance signals. New scheme reduces luminance and chrominance bandwidth to increase frequency separation between signals. To avoid proportionally reducing horizontal brightness resolution and horizontal color resolution, horizontal interlace of luminance signal and two color-difference signals used.

Marchman, Robert H.↗

NASA NTRS1987

Color-Video Thermal Maps

Computer-simulation method produces color-video representation of temperatures in combustion-chamber wall. New method displays two-dimensional or three-dimensional temperature variation. Colors in display represent specific temperature ranges. Colors change to show changes in temperature with flow, pressure, heat flux, and other factors during startup, steady-state operation, and shutdown.

Wagner, W. R.↗

NASA NTRS1986

Analysis of the retinex theory of color vision

Land's (1983) retinex algorithm is a model of human color constancy. The retinex algorithm is analyzed and its general properties are discussed. It is shown that the algorithm is too sensitive to changes in the color of nearby objects to serve as an adequate model of human color constancy.

Brainard, D. H.↗

NASA NTRS1986

Color enhancement of highly correlated images. I - Decorrelation and HSI contrast stretches

Conventional enhancements for the color display of multispectral images are based on independent contrast modifications or 'stretches' of three input images. This approach is not effective if the image channels are highly correlated or if the image histograms are strongly bimodal or more complex. Any of several procedures that tend to 'stretch' color saturation while leaving hue unchanged may better utilize the full range of colors for the display of image information. Two conceptually different enhancements are discussed: the 'decorrelation stretch', based on principal-component (PC) analysis, and the 'stretch' of 'hue' - 'saturation' - intensity (HSI) transformed data. The PC transformation in scene-dependent, but the HSI transformation is invariant. Examples of images enhanced by conventional linear stretches, decorrelation stretch, and by stretches of HSI transformed data are compared. Schematic variation diagrams or two- and three-dimensional histograms are used to illustrate the 'decorrelation stretch' method and the effect of the different enhancements.

Gillespie, Alan R.↗

NASA NTRS1987

IRAS colors of normal stars

Using stars from the Bright Star Catalog, supplemented by cool dwarf stars from the Gliese catalog, that were detected by IRAS, the authors define empirically the median intrinsic visual-to-infrared color indices for 'normal' stars as a function of IRAS wavelength, spectral type and luminosity class. Anomalously red stars are discussed. Two otherwise undistinguished F giant stars are found with significant excesses at 12 microns. Be stars differ markedly from nonemission B stars in their V-(12) indices due to contamination of the former by free-free emission. Both B and Be stars show large dispersions in V-(25) colors that are associated with the heating of local, but strictly interstellar, dust clouds by some of the non-emission B stars. The derived sequences of stellar colors are closely approximated by either simple blackbody predictions or by model-atmosphere calculations.

Cohen, Martin↗

NASA NTRS1987

Near-infrared imaging of Comet Halley: Discovery of a color gradient in the inner coma

Near-infrared images of Comet Halley were obtained in the standard J, H, and K bandpasses, on 3.5 Nov. 1985 with an HgCdTe camera at a 1.54 m telescope. Each image covers 38.4 arcsec on the side. A well defined gradient in the J-H and H-K colors within 5000 km of the nucleus is discovered with the bluest colors at the photocenter. Surface brightness profiles steeper than the canonical 1/rho are observed in the same region. Analysis indicates that the color gradient and the brightness profiles can both be explained by the presence of volatile (dirty ice) grains in the inner coma. An outburst of very small (Rayleigh scattering) dust particles could also account for the observations, however, this model is not supported by the spacecraft measurements. No obvious jets or other structures are observed.

Rieke, M. J.↗

NASA NTRS1987

Using Colored Stochastic Petri Net (CS-PN) software for protocol specification, validation, and evaluation

The specification, verification, validation, and evaluation, which make up the different steps of the CS-PN software are outlined. The colored stochastic Petri net software is applied to a Wound/Wait protocol decomposable into two principal modules: request or couple (transaction, granule) treatment module and wound treatment module. Each module is specified, verified, validated, and then evaluated separately, to deduce a verification, validation and evaluation of the complete protocol. The colored stochastic Petri nets tool is shown to be a natural extension of the stochastic tool, adapted to distributed systems and protocols, because the color conveniently takes into account the numerous sites, transactions, granules and messages.

Zenie, Alexandre↗

NASA NTRS1987

Future U.S. ocean color missions - OCI, MODIS and HIRIS

NASA has been working to develop an Ocean Color Imager (OCI). The Earth Observing Satellite Company (EOSAT) is considering flying an ocean and land wide-field color instrument which would meet specified requirements on Landsat 6 or 7 planned for launch in 1989 and 1991, respectively. It would provide eight ocean color channels for improved atmospheric correction and in-water algorithms, global coverage and near real-time data for operational uses. In the mid 1990's NASA is planning to fly a Moderate Resolution Imaging Spectrometer (MODIS) and a High Resolution Imaging Spectrometer (HIRIS) as part of the Earth Observing System on the Polar Platform of the Space Station. These instruments are array spectrometers which would provide full spectral resolution in the visible and infrared. This opens the possibility of separating different groups of phytoplankton, suspended sediments and other substances in the water.

Davis, C. O.↗

NASA NTRS1988

Spectrophotometry of Wolf-Rayet stars - Intrinsic colors and absolute magnitudes

Absolute spectrophotometry of about 10-A resolution in the range 3400-7300 A have been obtained for southern Wolf-Rayet stars, and line-free magnitudes and colors have been constructed. The emission-line contamination in the narrow-band ubvr systems of Westerlund (1966) and Smith (1968) is shown to be small for most WN stars, but to be quite significant for WC stars. It is suggested that the more severe differences in intrinsic color from star to star of the same spectral subtype noted at shorter wavelengths are due to differences in atmospheric extent. True continuum absolute visual magnitudes and intrinsic colors are obtained for the LMC WR stars. The most visually luminous WN6-WN7 stars are found to be located in the core of the 30 Doradus region.

Torres-Dodgen, Ana V.↗

NASA NTRS1989

Field-Sequential Color Converter

Electronic conversion circuit enables display of signals from field-sequential color-television camera on color video camera. Designed for incorporation into color-television monitor on Space Shuttle, circuit weighs less, takes up less space, and consumes less power than previous conversion equipment. Incorporates state-of-art memory devices, also used in terrestrial stationary or portable closed-circuit television systems.

Studer, Victor J.↗

NASA NTRS1988

Recognition of object domain by color distribution

For the image processing of an object in its natural image, it is necessary to extract in advance the object to be processed from its image. To accomplish this the outer shape of an object is extracted through human instructions, which requires a great deal of time and patience. A method involving the setting of a model of color distribution on the surface of an object is described. This method automatically provides color recognition, a piece of knowledge that represents the properties of an object, from its natural image. A method for recognizing and extracting the object in the image according to the color recognized is also described.

Mugitani, Takako↗

NASA NTRS1988

The absence of a color-distance trend in comets

New near-IR J-H and H-K observations of 23 comets have been obtained in the heliocentric distance range of 1 to 6 AU. No evidence is found for a color-distance trend in the present sample. Significant differences between the grain populations in different comets are pointed out. The results indicate that the color distributions are unimodal, and that, unlike asteroids, the comets cannot be classified into distinct color-defined groups.

Jewitt, D.↗

NASA NTRS1988

Differential color brightness as a body orientation cue

Ninety male and female college students reclining on their backs in the dark were disoriented when positioned on a rotating platform under a slowly rotating disk that filled their entire visual field. Half of the disk was painted with a brighter value (about 69 percent higher luminance level) of the color on the other half. The effects of red, blue, and yellow were examined. Subjects wearing frosted goggles viewed the illuminated disk for three rotations. The disk was stopped when the subjects felt that they were right side up. A significant proportion of subjects selected the disk position in which the brighter side of each of the three colors filled their upper visual field. These results suggest that color brightness as well as lighting variation could provide Space Station crew members with body orientation cues as they move around.

Barbour, Christopher G.↗