Colors on Mars

When a photograph taken under sodium light is later viewed in normal
lighting it appears a much deeper orange compared to the subjective
experience of being there. The brain performs automatic "white balance"
correction when it is immersed in colored light. This correction is not
as strong when the image only fills a small part of the field of vision
and the rest is illuminated by white light.

NASA carefully calibrates the colors of published images to match the
spectrum of ambient light on Mars. Would these pictures really match
the subjective experience of actually being there some day?

The first Viking images received from Mars were not color-calibrated. I
believe each color component was individually stretched to cover the
full range to maximize SNR with the highest gain applied to the
relatively weak blue signal. The result was an image that looked as if
it was taken somewhere in Arizona, with blue skies, reddish rocks and
even some greenish patches. The color calibration was later changed to
the much redder hues we usually see.

Some conspiracy theorists claim that this Earth-like view is what Mars
really looks like. I wonder if there is actually some truth in their
claims. No, I don't think NASA tweaked the colors "to make it look more
alien" because of some sinister motives. Perhaps the color correction
applied is just a little too correct?

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When a photograph taken under sodium light is later viewed in normal
lighting it appears a much deeper orange compared to the subjective
experience of being there. The brain performs automatic "white balance"
correction when it is immersed in colored light. This correction is not
as strong when the image only fills a small part of the field of vision
and the rest is illuminated by white light.

NASA carefully calibrates the colors of published images to match the
spectrum of ambient light on Mars. Would these pictures really match
the subjective experience of actually being there some day?

The first Viking images received from Mars were not color-calibrated. I
believe each color component was individually stretched to cover the
full range to maximize SNR with the highest gain applied to the
relatively weak blue signal. The result was an image that looked as if
it was taken somewhere in Arizona, with blue skies, reddish rocks and
even some greenish patches. The color calibration was later changed to
the much redder hues we usually see.

Some conspiracy theorists claim that this Earth-like view is what Mars
really looks like. I wonder if there is actually some truth in their
claims. No, I don't think NASA tweaked the colors "to make it look more
alien" because of some sinister motives. Perhaps the color correction
applied is just a little too correct?


IIRC the color enhancements were initially incorrect and were recalibrated
after an image including the American flag was sent back. The red was
noticed to be way out.

Ken

Newsuser wrote ...

Some conspiracy theorists claim that this Earth-like view is what Mars
really looks like. I wonder if there is actually some truth in their
claims. No, I don't think NASA tweaked the colors "to make it look more
alien" because of some sinister motives. Perhaps the color correction
applied is just a little too correct?

Search google with "mars sky color" and notice, that the physics says ... it
should be blue (when no dust) because of the Rayleigh scattering.
http://hyperphysics.phy-astr.gsu.edu...os/blusky.html
http://en.wikipedia.org/wiki/Rayleigh_scattering

Look at:
http://mars.gh.wh.uni-dortmund.de/mer/


P.S.
Viking cameras was the best calibrated cameras ever flown.

--
(STS)
Omne ignotum pro magnifico.