Explaining the Mars Photo Colorization

TaddyPorter writes "I've seen stories going around the 'net in regards to NASA editing photos of mars. Mainly, the sundial used for calibration showed different colors than the dial on mars. While a wide range of explanations were taking shape, the Pancam Payload Element Lead for the mission, Jim Bell of Cornell University, was kind of enough to explain the color differences."

Comments

In conclusion:

[CaptainAlbert]

From end of article (yes, I skipped straight there... :))

There is simply no point in adding on their site "caution these images are not 100% precisely actual colors" when no digital image is really 'actual colors'.

Quite. In fact, I'd go as far as to say that NASA expected most of the people who were scrutinising these pictures to have some experience with astronomical imaging, where almost nothing is "true" colour in that sense.

Personally, I'm in favour of as much rebalancing as it takes to make the images pretty. If they don't make full use of my eye's ability to perceive them, then what was the point of spending all that money obtaining them in the first place? So long as the raw originals are available too, who cares?

Conspiracy theorists

[Eric S Rayrnond]

The bizarre claims of conspiracy theorists just go on and on. If you go to their websites you can read more than any brain can handle. I have read literally dozens of things that ``prove'' the moon landings were faked, for example, and each one is rather easily shown to be wrong by anyone with experience in such things.

I think the problem here is twofold: we tend to want to believe (or at least listen to) conspiracy theories, particularly to do with space. Also, the evidence is presented in such a way that, if you are unfamiliar with the odd nature of the vacuum of space and of space travel, it sounds reasonable.

Great explanation, but why...

[darkstream]

...doesn't NASA throw the public a bone? This color correction controversy pops up everytime a probe successfully lands on Mars and sends pictures back. One would think that they would have a standard RGB style camera for publicity shots. Chances are they can only afford to put on cameras practical for the mission, but I still believe a better solution could be provided. It probably just wasn't important to them... ;) Perhaps next time a camera could be included that features lens that provide scentific data and that can double as a publicist for NASA - spitting out RGB standard images that require no color correction.

red skies vs blue skies

[Alien54]

This controversy has been seen earlier on SlashDot in this story on the Blue Skies of Mars.

The questions are, of course,

1. if there is a tinted color light source, what would the color target display on a normal color target? What would it show via the camera with the tinted light source
2. The sun is the same light source on mars as it is on earth, therefore it should be easy enough to take a solar spectrum and see what the degree of tinting is.
3. With an atmosphere at 1% or less of the earth, the spectrum could nearly be the same spectrum as in a vacuum
4. if the spectrums are essentially similar, then the color targets should be the same, say as on earth or in vacuum, given a clear day without dust and clouds, etc.
5. Of course,there is also the matter of the end result of different photo filters getting mis interpreted. However, JPL has published some pictures with red skies, and some with blue skies, as this item from the tin foil hat crowd. This has contributed to the controversy.

See also this earlier slashdot story on the Mars Sundials

So it looks like this particular annoyance has been around for a while.