14,176 research outputs found
NICMOS Imaging of a Damped Lyman-alpha Absorber at z=1.89 toward LBQS 1210+1731 : Constraints on Size and Star Formation Rate
We report results of a high-resolution imaging search (in rest frame
H- and optical continuum) for the galaxy associated with the damped
Lyman- (DLA) absorber at toward the quasar
LBQS 1210+1731, using HST/NICMOS. After PSF subtraction, a feature is seen in
both the broad-band and narrow-band images, at a projected separation of
0.25\arcsec from the quasar. If associated with the DLA, the object would be
kpc in size with a flux of Jy in
the F160W filter, implying a luminosity at {\AA} in
the rest frame of L at ,
for . However, no significant H- emission is seen,
suggesting a low star formation rate (SFR) (3 upper limit of 4.0
M yr), or very high dust obscuration.
Alternatively, the object may be associated with the host galaxy of the quasar.
H-band images obtained with the NICMOS camera 2 coronagraph show a much fainter
structure kpc in size and containing four knots of
continuum emission, located 0.7\arcsec away from the quasar. We have probed
regions far closer to the quasar sight-line than in most previous studies of
high-redshift intervening DLAs. The two objects we report mark the closest
detected high-redshift DLA candidates yet to any quasar sight line. If the
features in our images are associated with the DLA, they suggest faint,
compact, somewhat clumpy objects rather than large, well-formed proto-galactic
disks or spheroids.Comment: 52 pages of text, 19 figures, To be published in Astrophysical
Journal (accepted Dec. 8, 1999
Sloan Digital Sky Survey Imaging of Low Galactic Latitude Fields: Technical Summary and Data Release
The Sloan Digital Sky Survey (SDSS) mosaic camera and telescope have obtained
five-band optical-wavelength imaging near the Galactic plane outside of the
nominal survey boundaries. These additional data were obtained during
commissioning and subsequent testing of the SDSS observing system, and they
provide unique wide-area imaging data in regions of high obscuration and star
formation, including numerous young stellar objects, Herbig-Haro objects and
young star clusters. Because these data are outside the Survey regions in the
Galactic caps, they are not part of the standard SDSS data releases. This paper
presents imaging data for 832 square degrees of sky (including repeats), in the
star-forming regions of Orion, Taurus, and Cygnus. About 470 square degrees are
now released to the public, with the remainder to follow at the time of SDSS
Data Release 4. The public data in Orion include the star-forming region NGC
2068/NGC 2071/HH24 and a large part of Barnard's loop.Comment: 31 pages, 9 figures (3 missing to save space), accepted by AJ, in
press, see http://photo.astro.princeton.edu/oriondatarelease for data and
paper with all figure
Reflectance Transformation Imaging (RTI) System for Ancient Documentary Artefacts
This tutorial summarises our uses of reflectance transformation imaging in archaeological contexts. It introduces the UK AHRC funded project reflectance Transformation Imaging for Anciant Documentary Artefacts and demonstrates imaging methodologies
Morphing a Stereogram into Hologram
This paper develops a simple and fast method to reconstruct reality from
stereoscopic images. We bring together ideas from robust optical flow
techniques, morphing deformations and lightfield 3D rendering in order to
create unsupervised multiview images of a scene. The reconstruction algorithm
provides a good visualization of the virtual 3D imagery behind stereograms upon
display on a headset-free Looking Glass 3D monitor. We discuss the possibility
of applying the method for live 3D streaming optimized via an associated lookup
table.Comment: PDF, 8 pages, 4 Fig
Image-Processing Techniques for the Creation of Presentation-Quality Astronomical Images
The quality of modern astronomical data, the power of modern computers and
the agility of current image-processing software enable the creation of
high-quality images in a purely digital form. The combination of these
technological advancements has created a new ability to make color astronomical
images. And in many ways it has led to a new philosophy towards how to create
them. A practical guide is presented on how to generate astronomical images
from research data with powerful image-processing programs. These programs use
a layering metaphor that allows for an unlimited number of astronomical
datasets to be combined in any desired color scheme, creating an immense
parameter space to be explored using an iterative approach. Several examples of
image creation are presented.
A philosophy is also presented on how to use color and composition to create
images that simultaneously highlight scientific detail and are aesthetically
appealing. This philosophy is necessary because most datasets do not correspond
to the wavelength range of sensitivity of the human eye. The use of visual
grammar, defined as the elements which affect the interpretation of an image,
can maximize the richness and detail in an image while maintaining scientific
accuracy. By properly using visual grammar, one can imply qualities that a
two-dimensional image intrinsically cannot show, such as depth, motion and
energy. In addition, composition can be used to engage viewers and keep them
interested for a longer period of time. The use of these techniques can result
in a striking image that will effectively convey the science within the image,
to scientists and to the public.Comment: 104 pages, 38 figures, submitted to A
Perception and Mitigation of Artifacts in a Flat Panel Tiled Display System
Flat panel displays continue to dominate the display market. Larger, higher resolution flat panel displays are now in demand for scientific, business, and entertainment purposes. Manufacturing such large displays is currently difficult and expensive. Alternately, larger displays can be constructed by tiling smaller flat panel displays. While this approach may prove to be more cost effective, appropriate measures must be taken to achieve visual seamlessness and uniformity.
In this project we conducted a set of experiments to study the perception and mitigation of image artifacts in tiled display systems. In the first experiment we used a prototype tiled display to investigate its current viability and to understand what critical perceptible visual artifacts exist in this system. Based on word frequencies of the survey responses, the most disruptive artifacts perceived were ranked. On the basis of these findings, we conducted a second experiment to test the effectiveness of image processing algorithms designed to mitigate some of the most distracting artifacts without changing the physical properties of the display system. Still images were processed using several algorithms and evaluated by observers using magnitude scaling. Participants in the experiment noticed statistically significant improvement in image quality from one of the two algorithms. Similar testing should be conducted to evaluate the effectiveness of the algorithms on video content. While much work still needs to be done, the contributions of this project should enable the development of an image processing pipeline to mitigate perceived artifacts in flat panel display systems and provide the groundwork for extending such a pipeline to realtime applications
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