SEARCH · Search NASA

Results for “Digital Imaging”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 235 records · Page 13

All sources NASA NTRS DOE OSTI

NASA NTRS1994

SSME propellant path leak detection real-time

Included are four documents that outline the technical aspects of the research performed on NASA Grant NAG8-140: 'A System for Sequential Step Detection with Application to Video Image Processing'; 'Leak Detection from the SSME Using Sequential Image Processing'; 'Digital Image Processor Specifications for Real-Time SSME Leak Detection'; and 'A Color Change Detection System for Video Signals with Applications to Spectral Analysis of Rocket Engine Plumes'.

Crawford, R. A.↗

NASA NTRS2002

Characterizing Digital Camera Systems: A Prelude to Data Standards

This viewgraph presentation profiles: 1) Digital imaging systems; 2) Specifying a digital imagery product; and 3) Characterization of data acquisition systems. Advanced large array digital imaging systems are routinely being used. Digital imagery guidelines are being developed by ASPRS and ISPRS. Guidelines and standards are of little use without standardized characterization methods. Characterization of digital camera systems is important for supporting digital imagery guidelines. Specifications are characterized in the lab and/or the field. Laboratory characterization is critical for optimizing and defining performance. In-flight characterization is necessary for an end-to-end system test.

Ryan, Robert↗

NASA NTRS1994

Overview on METEOSAT geometrical image data processing

Digital Images acquired from the geostationary METEOSAT satellites are processed and disseminated at ESA's European Space Operations Centre in Darmstadt, Germany. Their scientific value is mainly dependent on their radiometric quality and geometric stability. This paper will give an overview on the image processing activities performed at ESOC, concentrating on the geometrical restoration and quality evaluation. The performance of the rectification process for the various satellites over the past years will be presented and the impacts of external events as for instance the Pinatubo eruption in 1991 will be explained. Special developments both in hard and software, necessary to cope with demanding tasks as new image resampling or to correct for spacecraft anomalies, are presented as well. The rotating lens of MET-5 causing severe geometrical image distortions is an example for the latter.

Diekmann, Frank J.↗

NASA NTRS1991

Rocket engine plume diagnostics using video digitization and image processing - Analysis of start-up

Video digitization techniques have been developed to analyze the exhaust plume of the Space Shuttle Main Engine. Temporal averaging and a frame-by-frame analysis provide data used to evaluate the capabilities of image processing techniques for use as measurement tools. Capabilities include the determination of the necessary time requirement for the Mach disk to obtain a fully-developed state. Other results show the Mach disk tracks the nozzle for short time intervals, and that dominate frequencies exist for the nozzle and Mach disk movement.

Disimile, P. J.↗

NASA NTRS1993

Depth-diameter ratios for Martian impact craters: Implications for target properties and episodes of degradation

This study determines crater depth through use of photoclinometric profiles. Random checks of the photoclinometric results are performed using shadow estimation techniques. The images are Viking Orbiter digital format frames; in cases where the digital image is unusable for photoclinometric analysis, shadow estimation is used to determine crater depths. The two techniques provide depth results within 2 percent of each other. Crater diameters are obtained from the photoclinometric profiles and checked against the diameters measured from the hard-copy images using a digitizer. All images used in this analysis are of approximately 40 m/pixel resolution. The sites that have been analyzed to date include areas within Arabia, Maja Valles, Memnonia, Acidalia, and Elysium. Only results for simple craters (craters less than 5 km in diameter) are discussed here because of the low numbers of complex craters presently measured in the analysis. General results indicate that impact craters are deeper than average. A single d/D relationship for fresh impact craters on Mars does not exist due to changes in target properties across the planet's surface. Within regions where target properties are approximately constant, however, d/D ratios for fresh craters can be determined. In these regions, the d/D ratios of nonpristine craters can be compared with the fresh crater d/D relationship to obtain information on relative degrees of crater degradation. This technique reveals that regional episodes of enhanced degradation have occurred. However, the lack of statistically reliable size-frequency distribution data prevents comparison of the relative ages of these events between different regions, and thus determination of a large-scale episode (or perhaps several episodes) cannot be made at this time.

Barlow, N. G.↗

NASA NTRS2003

Digital Particle Image Velocimetry (DPIV) Used for Space-Time Correlations in Nozzle Flow

An optical measurement technique known as Digital Particle Image Velocimetry (DPIV) was used previously to characterize the first- and second-order statistical properties of both cold and hot jet flows from externally mixed nozzles in NASA Glenn Research Center's Nozzle Acoustic Test Rig. In this technique, an electronic camera records particles entrained in a flow as a laser light sheet is pulsed at two instances in time. Correlation processing of the recorded particle image pairs yields the two-component velocity field across the imaged plane of the flow. The information acquired using DPIV is being used to improve our understanding of the decay of turbulence in jet flows-a critical element for understanding the acoustic properties of the flow. Recently, two independent DPIV systems were installed in Glenn's Small Hot Jet Acoustic Rig, enabling multiplane correlations in time and space. The data were collected over a range of different Mach numbers and temperature ratios. DPIV system 1 was fixed to a large traverse rig, and DPIV system 2 was mounted on a small traverse system mounted on the large traverse frame. The light sheets from the two DPIV systems were aligned to lie in the same axial plane, with DPIV system 2 being independently traversed downstream along the flow direction. For each measurement condition, the DPIV systems were started at a fully overlapping orientation. A polarization separation technique was used to avoid cross-talk between the two systems. Then, the DPIV systems fields were shifted axially apart, in successively increasing steps. The downstream DPIV system 2 was triggered at a short time delay after the upstream DPIV system 1, where the time delay was proportional to the convective flow velocity in the shear layer of the jet flow and the axial separation of the two DPIV systems. The acquired data were processed to obtain the instantaneous velocity vector maps over a range of time delays and spatial separations. The velocity fields from the different DPIV systems were then cross-correlated to determine the degree of correlation remaining in the flow as the downstream convection distance was increased. The new data provide Lagrangian measurements of the convective turbulent structures in the shear layer of an exhaust nozzle. These measurements, obtained in both cold and hot flows, will be used to validate and correct models for space-time velocity correlations-long a missing key to predicting jet noise.

Wernet, Mark P.↗

NASA NTRS1992

Bandwidth compression of the digitized HDTV images for transmission via satellites

This paper investigates a subband coding scheme to reduce the transmission bandwidth of the digitized HDTV images. The HDTV signals are decomposed into seven bands. Each band is then independently encoded. The based band is DPCM encoded and the high bands are encoded by using nonuniform Laplacian quantizers with a dead zone. By selecting the dead zone on the basis of energy in the high bands an acceptable image quality is achieved at an average of 45 Mbits/sec (Mbps) rate. This rate is comparable to some very hardware intensive schemes of transform compression or vector quantization proposed in the literature. The subband coding scheme used in this study is considered to be of medium complexity. The 45 Mbps rate is suitable for transmission of HDTV signals via satellites.

Al-Asmari, A. KH.↗

NASA NTRS1997

Light-Directed Ranging System Implementing Single Camera System for Telerobotics Applications

A laser-directed ranging system has utility for use in various fields, such as telerobotics applications and other applications involving physically handicapped individuals. The ranging system includes a single video camera and a directional light source such as a laser mounted on a camera platform, and a remotely positioned operator. In one embodiment, the position of the camera platform is controlled by three servo motors to orient the roll axis, pitch axis and yaw axis of the video cameras, based upon an operator input such as head motion. The laser is offset vertically and horizontally from the camera, and the laser/camera platform is directed by the user to point the laser and the camera toward a target device. The image produced by the video camera is processed to eliminate all background images except for the spot created by the laser. This processing is performed by creating a digital image of the target prior to illumination by the laser, and then eliminating common pixels from the subsequent digital image which includes the laser spot. A reference point is defined at a point in the video frame, which may be located outside of the image area of the camera. The disparity between the digital image of the laser spot and the reference point is calculated for use in a ranging analysis to determine range to the target.

Wells, Dennis L.↗

NASA NTRS1994

Simplified Generation Of Distance Images

Optoelectronic apparatus undergoing development intended to produce digitized images that contain three-dimensional information: brightness of each picture element in digitized image depends on distance from apparatus to corresponding location in scene. Does not contain mechanical scanners. Signal-processing circuitry in this apparatus simpler. Smaller, weighs less, and consumes less power. Potential applications include automated inspection, remote exploration, robotic manipulators, robotic vehicles, and maneuvering and docking systems.

Wesolowicz, Karl↗

NASA NTRS1993

The Visible Human Project of the National Library of Medicine: Remote access and distribution of a multi-gigabyte data set

As part of the 1986 Long-Range Plan for the National Library of Medicine (NLM), the Planning Panel on Medical Education wrote that NLM should '...thoroughly and systematically investigate the technical requirements for and feasibility of instituting a biomedical images library.' The panel noted the increasing use of images in clinical practice and biomedical research. An image library would complement NLM's existing bibliographic and factual database services and would ideally be available through the same computer networks as are these current NLM services. Early in 1989, NLM's Board of Regents convened an ad hoc planning panel to explore possible roles for the NLM in the area of electronic image libraries. In its report to the Board of Regents, the NLM Planning Panel on Electronic Image Libraries recommended that 'NLM should undertake a first project building a digital image library of volumetric data representing a complete, normal adult male and female. This Visible Human Project will include digitized photographic images for cryosectioning, digital images derived from computerized tomography, and digital magnetic resonance images of cadavers.' The technologies needed to support digital high resolution image libraries, including rapid development; and that NLM encourage investigator-initiated research into methods for representing and linking spatial and textual information, structural informatics. The first part of the Visible Human Project is the acquisition of cross-sectional CT and MRI digital images and cross-sectional cryosectional photographic images of a representative male and female cadaver at an average of one millimeter intervals. The corresponding cross-sections in each of the three modalities are to be registerable with one another.

Ackerman, Michael J.↗

NASA NTRS1975

Temporal registration of multispectral digital satellite images using their edge images

An algorithm is described which will form an edge image by detecting the edges of features in a particular spectral band of a digital satellite image. It is capable also of forming composite multispectral edge images. In addition, an edge image correlation algorithm is presented which performs rapid automatic registration of the edge images and, consequently, the grey level images.

Nack, M. L.↗

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 NTRS1981

Radiometry with nighttime DMSP images in digital form

The USAF Defense Meteorological Satellite Program (DMSP) spacecraft sends images to earth in the form of numbers. It has been common practice to erase the only digital records, the magnetic tapes, for reuse, after films (resembling photographs) have been created from the numbers. While the DMSP images have been widely used, their application in research has been hindered by both the lack of digital data and the lack of an authoritative source of related technical information. The character of the digital form is considered. Each image is essentially a three-dimensional list (X,Y,Z) in which X and Y represent the position coordinates of a pixel and Z is its associated radiance. Only the value of Z is given and the X-Y position must be deduced from adjunct information. Each original scan composed of 1464 pixels represents an area on the earth's surface about 3 km wide and 3000 km long. Strengths and weaknesses of the system with respect to research applications are considered, and concepts for the design of a nocturnal imager are discussed.

Croft, T. A.↗

NASA NTRS1995

Electronic Photography at the NASA Langley Research Center

An electronic photography facility has been established in the Imaging & Photographic Technology Section, Visual Imaging Branch, at the NASA Langley Research Center (LaRC). The purpose of this facility is to provide the LaRC community with access to digital imaging technology. In particular, capabilities have been established for image scanning, direct image capture, optimized image processing for storage, image enhancement, and optimized device dependent image processing for output. Unique approaches include: evaluation and extraction of the entire film information content through scanning; standardization of image file tone reproduction characteristics for optimal bit utilization and viewing; education of digital imaging personnel on the effects of sampling and quantization to minimize image processing related information loss; investigation of the use of small kernel optimal filters for image restoration; characterization of a large array of output devices and development of image processing protocols for standardized output. Currently, the laboratory has a large collection of digital image files which contain essentially all the information present on the original films. These files are stored at 8-bits per color, but the initial image processing was done at higher bit depths and/or resolutions so that the full 8-bits are used in the stored files. The tone reproduction of these files has also been optimized so the available levels are distributed according to visual perceptibility. Look up tables are available which modify these files for standardized output on various devices, although color reproduction has been allowed to float to some extent to allow for full utilization of output device gamut.

Holm, Jack↗

NASA NTRS1975

Analysis of the nebulosities near T Tauri using digital computer image processing

Direct plates of T Tauri taken with the 120-inch (3 m) and 36-inch (91 cm) Lick reflectors were digitized and analyzed using digital-computer image-processing techniques. Luminous emission protrusions extending to as far as 13-sec from T Tauri in position angles 170 deg, 210 deg, and 330 deg are shown. These features are variable and may contain a layered structure. The complex reflection nebula west of T Tauri (NGC 1555) appears to be an illuminated portion of a much larger dark nebula whose variability is due to obscuring material near the star.

Lorre, J. J.↗

NASA NTRS2001

Results of Click Workers Mars Crater Marking and Crater Classification

This paper presents several data tables on Mars Crater Markings and Crater Classifications. The tables include: 1) Craters observed in Mars Orbiter Camera (MOC); 2) Craters observed in Mars Digital Image Mosaics from Viking Orbiter images; and 3) Crater classifications in Mars Digital Image Mosaics from Viking Orbiter images.

Kanesky, Bob↗

NASA NTRS1991

Electronic Still Camera Project on STS-48

On behalf of NASA, the Office of Commercial Programs (OCP) has signed a Technical Exchange Agreement (TEA) with Autometric, Inc. (Autometric) of Alexandria, Virginia. The purpose of this agreement is to evaluate and analyze a high-resolution Electronic Still Camera (ESC) for potential commercial applications. During the mission, Autometric will provide unique photo analysis and hard-copy production. Once the mission is complete, Autometric will furnish NASA with an analysis of the ESC s capabilities. Electronic still photography is a developing technology providing the means by which a hand held camera electronically captures and produces a digital image with resolution approaching film quality. The digital image, stored on removable hard disks or small optical disks, can be converted to a format suitable for downlink transmission, or it can be enhanced using image processing software. The on-orbit ability to enhance or annotate high-resolution images and then downlink these images in real-time will greatly improve Space Shuttle and Space Station capabilities in Earth observations and on-board photo documentation.

Source record↗

NASA NTRS1999

Fidelity Analysis of Sampled Imaging Systems

Many modeling, simulation and performance analysis studies of sampled imaging systems are inherently incomplete because they are conditioned on a discrete-input, discrete-output model that only accounts for blurring during image acquisition and additive noise. For those sampled imaging systems where the effects of digital image acquisition, digital filtering and reconstruction are significant, the modeling, simulation and performance analysis should be based on a more comprehensive continuous-input, discrete-processing, continuous-output end-to-end model. This more comprehensive model should properly account for the low-pass filtering effects of image acquisition prior to sampling, the potentially important noiselike effects of the aliasing caused by sampling, additive noise due to device electronics and quantization, the generally high-boost filtering effects of digital processing, and the low-pass filtering effects of image reconstruction. This model should not, however, be so complex as to preclude significant mathematical analysis, particularly the mean-square (fidelity) type of analysis so common in linear system theory. We demonstrate that, although the mathematics of such a model is more complex, the increase in complexity is not so great as to prevent a complete fidelity-metric analysis at both the component level and at the end-to-end system level: that is, computable mean-square-based fidelity metrics are developed by which both component-level and system-level performance can be quantified. In addition, we demonstrate that system performance can be assessed qualitatively by visualizing the output image as the sum of three component images, each of which relates to a corresponding fidelity metric. The cascaded, or filtered, component accounts for the end-to-end system filtering of image acquisition, digital processing, and image reconstruction; the random noise component accounts for additive random noise, modulated by digital processing and image reconstruction filtering; and the aliased noise component accounts for the frequency folding effect of sampling, modulated by digital processing and image reconstruction filtering.

Park, Stephen K.↗