True mars color : Myth versus Fact [ UPDATED ] - Page 2

nebularain · #31 (**permalink**) 31-January-2004, 04:50 PM

Quote:

Originally Posted by majic

Recent Nasa image released from spirit (30 jan. 2004), presumably with the L4 filter instead of the more commonly used L2 filter (Near Infrared) :

As you can see, the colordisk is looking fine, and the color of the land is still similar to what it looked like in previous photos with L2 filter for red.

I am curious, how come the color of the surface looks a darker red? (I do admit, it does look cool, though!)

majic · #32 (**permalink**) 31-January-2004, 04:53 PM

Quote:

Originally Posted by nebularain

Quote:

Originally Posted by majic

Recent Nasa image released from spirit (30 jan. 2004), presumably with the L4 filter instead of the more commonly used L2 filter (Near Infrared) :

As you can see, the colordisk is looking fine, and the color of the land is still similar to what it looked like in previous photos with L2 filter for red.

I am curious, how come the color of the surface looks a darker red? (I do admit, it does look cool, though!)

I hypothise that, just like on earth, the time of the day and the atmospheric conditions have an impact on overall rendering of color and brightness. It's not a studio with perfectly similar lighting conditions all day long, obviously!

nebularain · #33 (**permalink**) 31-January-2004, 11:01 PM

Cool!

The Bad Astronomer · #34 (**permalink**) 01-February-2004, 12:40 AM

Yes, time of day has a lot to do with it, I think. Sand looks very different when lit from behind you than it does if lit from in front; this effect is called heiligenschein, and I talk about in reference to the Moon Landing "hoax" as well.

Dust in the air scatters light, and so images of the sky taken toward the Sun will look different than those taken away. Space artist Don Davis discusses this on his website.

The Bad Astronomer · #35 (**permalink**) 01-February-2004, 12:43 AM

Quote:

Originally Posted by majic

The only thing your link proves is that some journalist did a 1:1 copy from some rumours on the web

After reading the BBC article, I would say the reporter didn't even do that. He comments on NASA trying to make the images "true color", and leaves it at that.

Phobos, your post is grossly misleading. You might want to reread the article, and what you wrote.

George · #36 (**permalink**) 02-February-2004, 05:08 AM

In regards to true color from NASA, I think Dr. Bell addressed it nicely...

Quote:

Ultimately you are right that people will need the calibrated data to do the color balancing correctly. We are working on doing that and will eventually get all those images out to the public using the NASA/JPL "Planetary Image Atlas" web site. It will take several months or more to get the work done, however. In the meantime, we thought it would be best to get *something* out there, and so that's why we opted to get the raw data out fast, even though it's still raw. The team has taken some criticism for this within the planetary science community because not many past missions have adopted such an open-data policy.

Let them whine, I say. People want and deserve to see the pictures as soon as we do.

From >>> here <<<

No doubt they are working long and hard. "True color" from them can wait. I am enjoying your stuff, magic [(and others)], till then! 8) =D>

It would be nice if they could sub-out the color processing to a team of volunteers. Is stuff like this done?

[Note: I am not sure the last line is Dr. Bell's as I did not find the original news article.]

Lm Wong · #37 (**permalink**) 03-February-2004, 06:09 PM

Quote:

Originally Posted by Ian Goddard

Thanks for your insightful analysis Majic! This is an issue that should be addressed considering its popularity. I can't quite figure what the "true color" conspiracy theorists are seeing in terms of a devious motive to alter the color. It doesn't seem to make sense to me. But it is annoying that there is so much variation just for the simple reason that one should like to have as real a picture as possible. But this raises a deeper issue...

This may be a useful report: Solving the color calibration problem of Martian lander images

Other part of the analysis here and this rise an interesting issue about the Mars landscape colors.
http://www.biospherics.com/mars/color/color.htm

Plate I(a) is a portion of the first color picture taken on Mars by Viking 1. Some portion of the rocks and ground surface are perceived as green relative to the surrounding area. While this color is perceived as green, and is so called in this paper, the actual colors on Mars remain somewhat indeterminate. Thus, the Mars landscape was reported (NASA P-17164, July 1976) to be mostly "orange-red". More recently (Huck et al., 1977), a six channel spectrophotometric analysis of the Viking lander camera data found the surface of the planet predominantly "moderate yellowish brown" with variations including "moderate olive brown".

Lm Wong · #38 (**permalink**) 06-February-2004, 10:36 PM

Quote:

Originally Posted by majic

Quote:

Originally Posted by Ian Goddard

(Snip)......

This may be a useful report: Solving the color calibration problem of Martian lander images.

Ian, yes ...for me the whole problem you define is contained in the word "color balancing" or more commonly referred to as "whitebalance" ...and it is very, very complex. Well not really complex, it is very difficult to achieve properly. I read the report and it goes into quite some detail, but unfortunately it will not mean much to the "mars-color-conspirationists" . They have a tendency to skip everything that they percieve as threatening to their point of view, then look for quick other alternative ways as to why a few images are proof of NASA's giant cover-up

Do you have read it with attention?
The beginning of the abstract talk about the importance of true color...

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....True color is important for interpretation of physical, chemical, geological and, possibly, biological information about Mars.

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Accordingly, no consensus has emerged on the colors of the soil, rocks and sky of Mars. This paper proposes two techniques to eliminate color uncertainty from future images, and also to allow recalibration of past images: 1. Calibration of cameras at night through minimal atmospheric paths using light sources brought from Earth, which, used during the day, would permit calculation of red, green and blue intensities independent of scene illumination; 2. Use of hyperspectral imaging to measure the complete spectrum of each pixel.

This paper includes a calibration of a NASA Viking lander image based on its color chart as it appears on Earth. The more realistic Martian colors become far more interesting, showing blue skies, brownish soil and rocks, both with yellow, olive, and greenish areas.

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The weak link in the imaging process for both missions was the reliance on imaging color charts reflecting Martian ambient light. While the reflectivity of the charts is well known, the spectrum of their illumination on Mars is not. ?Calibrated? images are usually reddish, attributed to atmospheric dust, but hues range widely because of the great uncertainty in the illumination spectrum. Solar black body radiation, the same on Mars as on Earth, is minimally modified by the atmosphere of either planet. For red dust to change the spectrum significantly, reflected light must exceed the transmitted light. Were this the case, shadows would be virtually eliminated. Viking images show prominent shadows. Also, Pathfinder?s solar cells, activated by blue light, would have failed under the predominately red spectrum generally attributed to Mars.

Here is the BEEF

Quote:

The first color image (12A006/001) of the surface of Mars was taken July 21, 1976, at the Viking 1 site, one day after the landing. Immediately displayed on color monitors at JPL, as seen in Figure 1a, the landscape awed observers with its resemblance to that of Arizona. Typical desert colorations of soil and rock, ranging from umber sand to yellowish-brown and olivine-colored rocks stood out clearly under a blue sky. Two hours later, however, the official image was changed to the monotone of orange-red (NASA P-17164), Figure 1b, that, with few exceptions, has prevailed in NASA-published images of Mars ever since, as presented by Mutch et al.[1]. However, a spectral analysis of color images of the Viking 1 site reported[2] a broader palate. The paper made the first, and perhaps only, reported use of JPL?s Image Processing Laboratory to analyze digitally the red, green and blue color channels of the images taken by the Viking 1 lander camera. In addition to studying the color images, their RGB components were transformed into saturation, hue and intensity components to enhance subtle deviations. When these components were equally amplified to produce an equal average sensitivity over the spectral bandpass, the resulting ?radiometric? (closest possible approach in appearance to a human observer) images very closely resembled the first color image (12A006/001). Among the range of colors, the paper reported that some of the rocks exhibited greenish patterns that apparently changed between images taken 301 sols apart. Radiometric images of lichen-bearing terrestrial rocks taken and processed through the same system as were the Viking images showed a close resemblance of the lichen colonies to the greenish patches on the Mars rocks. Inclusion in the analysis of three near-IR channels available on the Martian images enhanced the greenness of the patches that were, to the sensitivity of the method, virtually indistinguishable from the lichen colonies on the terrestrial rocks.

Although the authors of that paper drew no conclusion about the biological implication of their findings, the mere comparison of the Mars images with lichen produced a major controversy with the orange-red Mars majority. The paper was heavily criticized by NASA officials who, upon viewing the images, contended they saw no evidence of the features claimed[3]. Even when the greenish colored areas were confirmed in subsequent reports[4],[5], those authors took special care to avoid any possible biological implication.

JonClarke · #39 (**permalink**) 07-February-2004, 02:22 AM

The first thing to note about those papers is that by are both by Gil Levin. That immediately alerts one to the fact that he has a particular angle. This does not make what they say wrong, but does impart a particular slant, or perhaps shading

to them. The papers have to be read accordingly.

The second thing to note is that only one, Levin and Straat, appears to be in a peer reviewed journal, all of 26 years ago. A lot of work has happened since then which that paper cannot take into account. The other is undated and appears to be a web only article. This again does not mean to say it is worthless, but does mean that it has not been independently reviewed.

Thirdly, the Levin and Straat paper was not published in a journal specialising in planetary science or remote sensing, but in the Journal of Theoretical Biology. This is not the logical home for a paper that deals in issues of image processing and spectral analysis. While this is not necessarily a fault, is is an alert to some issues as to why it was not published in a more relevant journal. Was it submitted to these and rejected? Did Levin and Straat think it might have been rejected if it had? Certainly one might question the abilities of the the typical reviewer of JTB to critically analyse such a paper. In JTB it is also unlikely to be read by the prime audience of image analysts, astrobiologists, and planetary scientists.

Fourthly, note that the date is only 2 years after the Viking landing. More would have been made of these findings in the 26 years since had this paper been considered to offer something significant. This again does not make the authors wrong (papers have been years ahead of their time, like Wallace's 19th century papers on Mars), but it it does indicate caution.

Onto the papers themselves. With respect to the "true colour" issue please not what Levin and Straat say, especially in the last sentence:

"The Viking cameras have six spectrally narrow band detectors, three in the visible and three in the near infrared. The use of all six channels has been shown (Huck et al., 1977) to provide the most accurate color rendition. Because many of the images in our study had not been taken in six channels, three component color reconstruction was used. The three components correspond approximately to Blue, Green, and Red. The color reconstruction of these images was performed in a "radiometric" sense, meaning that the components were each linearly amplified to effect an equal average sensitivity over the spectral bandpass. Therefore, the
reconstructed triplet, while possessing the same general color characteristics, is not intended to be an exact photometric reproduction of the actual sense as perceived by a human observer."

The thrust of the paper is that there have been subtle changes in the distribution of greenish patches on the rock which the authors describe as possibly algae or lichen. While interesting, the changes are very marginal and the interpretation is hardly conclusive. Ignoring for the moment the issue of how life can survive in an environment drenched by UV-C, the absence of oxygen points to the absence of of both oxygen photosynthesis and aerobes. Also, why would any partial lifeforms be green? We now that oxygen photosynthesis is not occurring, therefore no chlorophyll. Even if oxygen photosynthesis were occurring, why would martian organisms necessarily use a green pigment? Even on earth, many organisms, especially those in harsh environments, hide the
green of chlorophyll.

The differences in the second paper (Levin and Levin) between Viking images and those produced by others are really fairly minor. Even if more correct than They certainly do not support the contention of cover up or denial of the "true" colour of Mars.

Jon

Lm Wong · #40 (**permalink**) 07-February-2004, 03:01 AM

Quote:

Originally Posted by JonClarke

The differences in the second paper (Levin and Levin) between Viking images and those produced by others are really fairly minor. Even if more correct than They certainly do not support the contention of cover up or denial of the "true" colour of Mars.
Jon

You gives lot of good arguments.However i will stay focus about the true color issue for now.

Quote:

The first color image (12A006/001) of the surface of Mars was taken July 21, 1976, at the Viking 1 site, one day after the landing. Immediately displayed on color monitors at JPL, as seen in Figure 1a, the landscape awed observers with its resemblance to that of Arizona. Typical desert colorations of soil and rock, ranging from umber sand to yellowish-brown and olivine-colored rocks stood out clearly under a blue sky. Two hours later, however, the official image was changed to the monotone of orange-red (NASA P-17164), Figure 1b, that, with few exceptions, has prevailed in NASA-published images of Mars ever since, as presented by Mutch et al.[1].

So,Why Two hours later the official image was changed to the monotone of orange-red that, with few exceptions, has prevailed in NASA-published images of Mars ever since, as presented by Mutch et al?

http://mars.spherix.com/spie2003/SPI...olor_Paper.htm

ArchAngel · #41 (**permalink**) 07-February-2004, 03:13 AM

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"The facts, gentlemen, and nothing but the facts, for careful eyes are narrowly watching"...Isaac Asimov

NASA says:

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Actual data from Mars Exploration Rover Spirit´s panoramic camera is mapped on top of these lines as dots. The plot demonstrates that the observed colors of Mars match the colors of the chips, and thus approximate the red planet´s true colors. This finding is further corroborated by the picture taken on Mars of the calibration target, which shows the colored chips as they would appear on Earth.

But it cannot be. The data is not there to create this image.

Or this one either:

Nasa says:

Quote:

These are the first images sent back from the panoramic camera on the Mars Exploration Rover Spirit since the rover experienced communications problems on the 18th sol, or martian day, of its mission. They were acquired at Gusev Crater, Mars, on Sol 26 (Jan. 29, 2004), showing that the camera´s health remained excellent during Spirit´s recovery.

There is no Sol 26, and there is no match with any of the published images.

These images from the press page could not have come from any images published for Spirit.

http://marsrovers.jpl.nasa.gov/gallery/all/spirit.html

Sol 33: No image of sundial

Sol 30: No image of sundial

Sol 29: No image of sundial

Sol 16: Only two images that are not correct filters for color, and shadow is in wrong position.

Sol 15: No image of sundial

Sol 14: Lander in frame above sundial, not the ground

Sol 13: No image of sundial

Sol 12: No image of sundial

Sol 11: No image of sundial

Sol 10: No image of sundial

Sol 9: No image of sundial

Sol 8: No image of sundial

Sol 7: No image of sundial

Sol 6: First two images from R2 and R7 filters cannot create color, rocks are different. All other sundial images shadow is too long.

Sol 5: Lander in image above sundial. Rover on pad.

Sol 4: Rover on pad

Sol 3: Rover on pad

Sol 2: Rover on pad

Sol 1: No image of sundial

NASA has failed to provide the raw data for both of the press page images that they are using to prove the color of Mars.

dummy · #42 (**permalink**) 07-February-2004, 03:17 AM

You already posted this in the other thread and it was explained. JPL not posting every image really has no relevance to the colour of mars surface. The images come from raw data that is not published on the Mars rover site.

ArchAngel · #43 (**permalink**) 07-February-2004, 03:25 AM

Quote:

You already posted this in the other thread, and it really has no relevance to the colour of mars surface. The images come from raw data that is not published on the Mars rover site.

These are the only 'color' images with both the sundial, and the ground in the same frame, and there is no way to prove that they are real.

They cannot be duplicated for verification.

Until the raw data is released these images cannot be proof of the color of the surface.

Are there any other color images on the press page that use data not on the site?

Seeing how quickly they have put up other images since why in the last week from when Sol 26 was supposedly received have they not got around to posting them yet?

A whole week?

dummy · #44 (**permalink**) 07-February-2004, 03:32 AM

I swear this is like headbutting a brick wall.

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They cannot be duplicated for verification.

Why do they need to be. I'd sooner trust a proper JPL camera engineer's judgement and expertise than someone who spent 5 seconds merging filter images JPL freely released.

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Until the raw data is released these images cannot be proof of the color of the surface.

Like its been mentioned over and over in the other thread, you cannot just merge these 3 channels and magically get a TRUE COLOUR IMAGE. Taking raw images and simply merging them proves nothing, and if you think it does you seriously need to read up on digital photography, or get your brains checked.

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Seeing how quickly they have put up other images since why in the last week from when Sol 26 was supposedly received have they not got around to posting them yet?

They've probably been busy with other things (fixing spirit, planning the mission, etc). Either wait and see if they publish them, or just wait for the entire raw image archive to be released in the PDS.

ArchAngel · #45 (**permalink**) 07-February-2004, 03:38 AM

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Like its been mentioned over and over in the other thread, you cannot just merge these 3 channels and magically get a TRUE COLOUR IMAGE. Taking raw image and merging them proves nothing, and if you think it does you seriously need to read up on digital photography, or get your brains checked.

They came very close in these images. Closer than can be shown in any other images.

I understand it is not so simple as merging three channels, and I know more about digital photgraphy than you imply.

My brain works fine. Thank you for your concern.

dummy · #46 (**permalink**) 07-February-2004, 03:41 AM

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They came very close in these images. Closer than can be shown in any other images.

That's simply not true. All they did was merge 3 channels. They performed no balancing to the intensity or contrast of each channel. Anyone can do the same thing by simply following the instructions the person left on their site. How do they even know they used the right filter images?

Quote:

I understand it is not so simple as merging three channels, and I know more about digital photgraphy than you imply.

So then why do you persist with this silly nonsense over merging 3 channels as being proof of a photo? This was all explained in detail in the thread you started, and you've simply ignored that and come to this one.

Quote:

These are the only 'color' images with both the sundial, and the ground in the same frame, and there is no way to prove that they are real.

Opportunity, Sol 001
1P128289773ESF0000P2107L4M1.JPG
1P128289457ESF0000P2107L5M1.JPG
1P128289489ESF0000P2107L6M1.JPG

Theres also most of the other filters on there. These images contain the dial as well as a small section of the martian soil at the top.

ArchAngel · #47 (**permalink**) 07-February-2004, 03:49 AM

Let me rephrase.

They are the only ones that NASA has produced, and presented as color.

How close to "true color" do you get by simply merging the ones from Sol 1?

dummy · #48 (**permalink**) 07-February-2004, 03:56 AM

Also

Spirit, Sol 014
2P127608578EFF0309P2851L2M1.JPG
2P127608800EFF0309P2851L4M1.JPG
2P127608647EFF0309P2851L5M1.JPG
2P127608720EFF0309P2851L6M1.JPG
2P127608494EFF0309P2850L7M1.JPG