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

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"As I lay beneath the Southern Cross, the stars tell more than I could" . . . David Meece

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!

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Quid quid latine dictum sit, altum viditur.

Cool!

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"As I lay beneath the Southern Cross, the stars tell more than I could" . . . David Meece

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.

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.

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

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.]

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Lighten up! This is a stellar board!

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".

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

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

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

NASA says:


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

Or this one either:



Nasa says:

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.

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.

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?

I swear this is like headbutting a brick wall.

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.

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.

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.

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.

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?

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.




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.

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?

Also

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


Originally I was just going to repeat myself again in saying that I (or anyone who does not have direct access to extensive info about the images) cannot merge these pictures and say how close to `true colour` they are, but I figured you would argue with me so I did it anyway. However, I'll even disclaimer it myself.

I do not know what levels of each color to use, or what filters to use. There is a 99.999% chance these colours are wrong.

I used L4/L5/L6 on each image. I also created a version that I reduced blue 40% / green 20% just to show how similar the dial colours are, even with the colour changes. Notice how the surface changes shades considerably though. This is also a 20 second rush job, so I didnt bother to contrast out the white areas (they appear a creamish colour in my modified versions):

altered images deleted by The Bad Astronomer

Assume the left one is an unadjusted merge, and the right has blue and green reduced.

The sundial in the unendited merge looks almost exactly as it does in the calibration image taken on earth.

The white in the dial is orange in the right, and the ground is much redder.

I do not pretend to know what to do to obtain the proper color balance, and you admit you don't either, but the simple L4 L5 L6 merge you have done looks to be the best example yet, and it only took you a short time to produce.

As I said above the images, I didn't touch the contrast on each channel so white appears as cream. But even so, take the following example:

What colour is a white piece of paper when you take it outside on a bright sunny day? Now what colour is that same piece of paper when you take it outside on a very orange/red sunset?

In the sundial pics from NASA using the missing data the white is very white, and the ground is much redder than in either pic you posted.

The sun is almost dircety overhead in the Sol 14 images. It is not dusk, or dawn.

But if the sky is red/pink/cream it is going to tint the colour of everything. If I increase the contrast on my blue/green channels the dial appears close to white:



Yet the ground is a very similar colour to that shown on the JPL site. Mine is slightly darker, but what can you expect from someone who doesn't have experience with the rover pan cam.

The main thing you need to realise is that making a 100% accurate true-colour image is impossible, and making an image close to true colour will be a different process for every single image. Theres no one way to do it, because each image taken will be slightly different depending on the property of Mars/Rover/Camera/Things on the image/etc. Some images will be closed to true colour when you use one set of filters, some will be closer with others. Some will need to be brightened, some darkened, some need less red, some need less blue, some will never be close to true colour.

People seem to expect the sundial to show pure shades of gray.

Why they do this is puzzling me - Somehow they are expecting the light to be perfectly "white" on mars, as if it could not be affected by dust in the atmosphere, different times of the day, different angle of the sun and so forth.

We do not know what color the _light_ has on mars. However trying to change the colors of ANY image to make the disc show white and pure tones of colour-less gray, is silly and naive.

I have photographed many subjects on earth, since this is what I do for a living, and I have thousands of frames in my collection that show "SKEWED" colors - In the morning, in the late afternoon, during overcast days and so forth......white objects in red or yellow light should not look white - they should appear to have a cast that matches the color of the light.

I can *MAKE* the pictures look like its pure perfect daylight however - this is a simple process called "graybalancing" - if I can find a spot in my photos that has a tone of what SHOULD have been "pure colourless gray", the entire colorspectrum of the image whill adapt to that. You can find it in any Photoshop version, under the "Curves" tool.

The result can be that an image indeed looks "more like regular daylight", but is this what I want? No - I want it to look like I saw it!

An example I made :

__________________
Quid quid latine dictum sit, altum viditur.

The complete report:
http://www.biospherics.com/mars/
In 1997, Biospherics' President and CEO,
Dr. Gilbert V. Levin, announced his new conclusion that his 1976 Viking Labeled Release (LR) life detection experiment found living microorganisms in the soil of Mars.
Objective application of the scientific process to 21 years of continued research and to new developments on Mars and Earth forced this conclusion. Of all the many hypotheses offered over the years to explain the LR Mars results, the only possibility fitting all the relevant data is that microbial life exists in the top layer of the Martian surface.
Nasa scientists have read it
"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."
http://mars.spherix.com/spie2003/SPI...olor_Paper.htm
Read the report from 1997 (cited above)
http://www.biospherics.com/mars/
Read the 1997 report for details
http://www.biospherics.com/mars/
Here is the interesting part.
Have you trying to find the first Viking Color Image labeled 12A006/001.

PLATE I. (a) Enlarged portion of radiometric color picture of Viking lander site 1, taken sol 1. Viking Picture 12A006/001. (b) Same view taken sol 302 showing changes on rocks and ground surface. Viking Picture 12Dl25/302.
I quote that part again
Where is the original (12A006/001) ????
From NASA Planetary Photojournal You can find this note at the bottom Image Note:
CE LABEL 12A006/001

First Color Image From Viking Lander 1
http://photojournal.jpl.nasa.gov/catalog/PIA00563

I find that one of the Viking 1 Landing Site a little over a month after landing.
http://nssdc.gsfc.nasa.gov/imgcat/ht...l1_12b069.html

What exactly is your point discussing images more then TWO DECADES old?

I'm certainly not going to spend time on them - NASA only had a very crude idear of the colors and contrasts of mars.

Let's keep this on-topic, we are now lightyears ahead of the colortechnology of the Viking landers.

__________________
Quid quid latine dictum sit, altum viditur.

[/quote]
Note I deleted my original post .This one is more concise to answer your question.
Do you mean than the cameras on Viking were not good enough?
Here the description of the equipment.
http://pdsproto.jpl.nasa.gov/catalog...box=VL1%2FCAM2
Nasa effectively have quickly adopted the altereted red color...from their secret receipt if it is red it`s good.
:wink:
http://photojournal.jpl.nasa.gov/catalog/PIA00563
Rather than giving the original images provided by the Vikings landers who were rarely provided to the general public...

See the page below for other images.
http://www.marssociety.org.uk/articles/artid02a.htm

Added from Nasa NSSDC Image Catalog
http://nssdc.gsfc.nasa.gov/imgcat/ht...der_page1.html
http://nssdc.gsfc.nasa.gov/imgcat/ht...der_page1.html

Edited for words correction.

You can get a better color image from the Mars Rovers by assigning an RGB value to each of the 5 color images and combining them, rather than using only 3 filters R, G, or B. Here are most of the Rover images converted that way:

http://xpda.com/mars

Bob Webster

Regarding ArchAngel, it was pointed out in the earliest discussions of how to do color combinations, any picture that has the brightest object plain white and has all colors represented will produce a fairly good blend from a straight RGB color combination, no need to adjust the brightness levels.

This is because of the way the sampling and transfer work. The grayscale images in each color band are stretched to make the lightest object/location white and the darkest black. In order to combine three separate filter images, you need to know something about that stretch in order to remove it. However, if the image has the brightest object/location a white object, then in all images there will not be much stretch to make the lightest gray to white. Add to that the darkest typically being a shadow, or black. Thus since the images were not stretched disproportionately, a simple recombination will put them together at about the same relative brightnesses. Thus the image appears pretty close to original.

This does not work when looking at objects not balanced, such as landscapes. If they are color skewed (i.e. have high color level in one band), the other images will stretch significantly to fill the full grayscale transmission levels. Then when you recombine, the blue end will be brighter than it should, and the images will be color skewed.

I don't think that was specifically what JonClarke meant. Rather, when a paper is refereed in a technical journal, it is typically refereed by another expert in that field. Thus any flaws should be detectable by the reviewer, or are more likely to be noticed. However, by publishing in an alternative journal, the referees are less likely to be knowlegable in the specific field of the paper, and thus more likely to miss details the in-field expert would catch. At least, that was what I think he meant.

On second read, perhaps there is more to the point. If one is trying to reach as specific community, it is best to publish in the journals they pay attention to, and not in journals they ignore or don't even know the existence of. I suppose on that line showing NASA is aware of the article at least has some merit, though that isn't exactly a slam dunk. After all, the term "NASA scientists" is a very nebulous term to mean anything from paid NASA civil servants to research partners at universities and private enterprises running payloads on NASA vehicles. To say some NASA officials responded is a far cry from saying the bulk of interested parties were aware of it.

And so NASA released an image, and then very quickly replaced it with a different image. So what? They corrected the image based on refining the data. Scary!

I just don't get this. NASA is evil and accused of conspiracy because they reserve data for a limited time in cases like the MOC and Malin, but then they are evil and covering things up by releasing the raw data quickly from the MERs. In other words, they can't win.

So you anti-green (no organic matter) on Mars guys must be starting to sweat a little huh? Methan and finally some open disclosure on those pesky ESA photos showing green. Sometimes the "establishment" uses conspiracy as a way of buying time: http://www.rednova.com/news/stories/.../story002.html