Released 10 June 2004This colorization is the result of a
collaboration between THEMIS team members at Cornell University and
space artist Don Davis, who is an expert on true-color renderings of
planetary astronomical objects. Davis began with calibrated and
co-registered THEMIS VIS multi-band radiance files produced by the
Cornell group. Using as a guide true-color imaging from the Hubble Space
Telescope and his own personal experience at Mt. Wilson and other
observatories, he performed a manual color balance to match more closely
the colors of previous visual Mars observations. He also did some manual
smoothing and other image processing to mimimize the effects of residual
scattered light in the images. The result is a view of Mars that invites
comparisons to Earth; a scene that one might observe out the window on a
flight over the southwest United States, but not quite.
Initial image processing and calibration by THEMIS team members J. Bell,
T. McConnochie, and D. Savransky at Cornell University; additional
processing and final color balance by space artist Don Davis.
Image information: VIS instrument. Latitude -0.7, Longitude 282.9 East
(77.1 West). 19 meter/pixel resolution.
The THEMIS VIS camera is capable of capturing color images of the martian
surface using its five different color filters. In this mode of operation,
the spatial resolution and coverage of the image must be reduced to
accommodate the additional data volume produced from the use of multiple
filters. To make a color image, three of the five filter images (each in
grayscale) are selected. Each is contrast enhanced and then converted to
a red, green, or blue intensity image. These three images are then
combined to produce a full color, single image. Because the THEMIS color
filters don't span the full range of colors seen by the human eye, a
color THEMIS image does not represent true color. Also, because each
single-filter image is contrast enhanced before inclusion in the
three-color image, the apparent color variation of the scene is
exaggerated. Nevertheless, the color variation that does appear is
representative of some change in color, however subtle, in the actual
scene. Note that the long edges of THEMIS color images typically contain
color artifacts that do not represent surface variation.
Image information: VIS instrument. Latitude -0.7, Longitude 282.9 East
(77.1 West). 19 meter/pixel resolution.
Note: this THEMIS visual image has not been radiometrically nor
geometrically calibrated for this preliminary release. An empirical
correction has been performed to remove instrumental effects. A linear
shift has been applied in the cross-track and down-track direction to
approximate spacecraft and planetary motion. Fully calibrated and
geometrically projected images will be released through the Planetary
Data System in accordance with Project policies at a later time.
NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission
for NASA's Office of Space Science, Washington, D.C. The Thermal Emission
Imaging System (THEMIS) was developed by Arizona State University, Tempe,
in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS
investigation is led by Dr. Philip Christensen at Arizona State
University. Lockheed Martin Astronautics, Denver, is the prime contractor
for the Odyssey project, and developed and built the orbiter. Mission
operations are conducted jointly from Lockheed Martin and from JPL, a
division of the California Institute of Technology in Pasadena.
