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Old January 12th 04, 05:32 AM
Andrew K.
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Default Spirit color wheel not being used?

Conan,

Assuming that you mean the 4 color blocks in the corners of the sundial, I
suspect the scientists and engineers are using, and will continue to use, this
information. The image you refer to has been released for public consumption
and is probably not being used by the scientists and engineers.

I don't know the details about the design of the PanCam, but most color imagers
used on spacecraft are actually black & white (i.e. a single ccd). Color
images are created by using a "filter wheel" inside the imager. As a result,
in order to get a full color image, three separate images are required.

As for the colors being different, I can think of several possibilities

1) If the PanCam is of the design I describe above and the software calibrated
to the "correct" colors as seen on Earth prior to launch, then this is how the
colors would appear to us (human beings). -- the most likely scenario, IMHO.

2) This is one of several images that are being used to determine how the
colors change as the sun moves and as the particulate levels change. We use a
similar technique here to determine the levels and types of pollution in the
air.

3) Properly calibrated, the image may have looked like places here (e.g., the
Painted Desert in the USA) rather than another planet, so the public affairs
office decided not to release such an image at this time.

4) Properly calibrated, the image may look like a computer generated picture
instead of a real one.

5) The data for one of colors at the location of the sundial was bad (CRC
mismatch on that particular packet).

I have several other possibilities in mind, but this is a start.

Andrew K.

Conan Ford wrote:
I wonder what the purpose of the color wheel is, when I see images like
this:

Go to http://photojournal.jpl.nasa.gov/cat...=pia05015click
on the high resolution version and then click on the Full-Res JPEG, (or
TIFF it you want). I've linked them below as well. Incidentally the
medium res version is missing part of the center of the picture.

medium res:
http://www.jpl.nasa.gov/mer2004/rove...2004/video.jpg
high res:
http://photojournal.jpl.nasa.gov/cat...umber=pia05015

the colors on the color wheel do not at all look like the color wheel
he
http://www.jpl.nasa.gov/mer2004/rove...s/image-2.html

Specifically, there is no green or blue visible on the color wheel in
the mars images, unlike the images on the page showing the color wheel
alone. In addition, the blue has been changed to a brilliant red. I'm
wondering the point of a color wheel when it does not appear to be used
properly.