True Color Images from Mars Rovers

i don't understand why we can't get the good color or why people say false color or true color.


the rovers have good cams and filters, right?


so what is the problem?

mars has the same sun, minerals, etc, even an atmosphere. with o2 close to the ground.

doesn't make lots of sense to me nobody can figure it out, lol!

so these filters have to be inplace before the pic is taken?

not like music where you can record "dry" then add fx's?

Originally posted by zorgon
Well if that was true about the lower gravity and the thinner atmosphere... then the same would apply on the Moon even more so because it supposedly has less gravity that Mars and an even thinner atmosphere...

So we should see dust floating around the Lunar atmosphere for long periods of time as well, by that logic, should we not?

Not really, the Moons atmosphere is so extremely tenuous that it might as well be considered a vacuum environment. Just to compare, the Moon's atmosphere is 0.3 nPa compared to Mars' 600,000,000,000 nPa (or 0.6 kPa.).

Mars' atmosphere also extends higher from the surface than Earth's (10.8km for Mars, 6km for Earth), so dust particles can be thrown higher where the wind speeds are faster. Combine that with the lower gravity and you could probably have dust suspended in the air for some time.

I guess we'll find out one way or another when Curiosity gets to Mars and takes unfiltered photos with its colour camera.

Originally posted by zorgon
Ah well here in America we say skeptic and true color.. I wasn't aware that Portugal used Queen's English

We use what we want to, and when I have to write in English I prefer the real English to its "lite" version.

If we were "talking" in Portuguese none of these confusions would exist, because we do not use those terms, we would talk about "real colours" instead of "true colours" and about "relatively real colours" or "colours close to reality".

Speaking about it, I don't know if you noticed that I write "true colour" but that I wrote "Truecolor", because the Wikipedia link you provided talks about a specific word that is used more in a commercial way than a way of classifying how close to reality a computer reproduction of a real scene is.

In Portuguese I would still use Truecolor because it's a name.

So what colour do you think the Martian sky looks like if you were standing on Mars on a clear day at noon? And would that be a 'true colour' or a 'false colour'

On a clear day (meaning a dust free atmosphere) I think I would see a blueish sky, but judging by the photos I don't know if it would be a darker blue or a lighter blue, seeing that in some photos the sky looks white.

That would obviously be true colour, because I would be looking at the original and not at reproduction. It would never be Truecolor or false colour because Truecolor is just something like a commercial name and false colour means that some (or all) colours were replace by other colours to help visualising something.

But if I had sunglasses on (something strange on a planet that gets less sunlight than we get on Earth) then I would be seeing false colours, because the tinted lens would replace some colours with different colours. But having said that, they would also be true colours because those were the ones I was really seeing.

If some else was there with me then the colours that person (or alien) would see would be true colours for him/her/it, even if they looked different from the ones I was seeing.

reply to post by fooks


I thought you were talking about night-vision like in video cameras, that use infrared light up to 1000 nm.

If that's the case then the right panoramic camera has night-vision when using any of the filters (that go from 754 nm up to 1009 nm) except the first, that is a 430 nm filter.

If you were talking about light amplification, then that's used in the same way as in any photo camera, with longer exposures. That's how they took photos of stars.

If you were talking about thermal vision, then no, they do not have it.

Originally posted by zorgon
Well if that was true about the lower gravity and the thinner atmosphere... then the same would apply on the Moon even more so because it supposedly has less gravity that Mars and an even thinner atmosphere...

No, I see I wasn't clear.

The thinner atmosphere makes it harder for the dust to remain up in the air, while the weaker gravity makes it easier, so the best circumstances to have a dusty atmosphere would be a weak gravity and a thick atmosphere, that way it would be easier (because of the weak gravity) for the dust to get up in the air and it would be harder (because of the thicker atmosphere and the weak gravity) for the dust to fall.

So we should see dust floating around the Lunar atmosphere for long periods of time as well, by that logic, should we not?

No, because of what I said above and because there isn't a easy way to get the Moon dust high enough, there are no strong winds on the Moon and there is no other way (that we know) to send the dust that high.

reply to post by ArMaP


yes, sorry, FLIR camera.

and a motion sensor game cam type thing with the light amplification.

a big air horn and strobe lights!

That ESA color picture of that vally looks like a crystal clear lake, where the depth of the water creates the blue.

So to see if there was water, i flew over :-)

reply to post by zorgon

Why is it that the ESA pics have a slightly surrealistic or animated feel to them? What do they do differently than NASA does in post processing? Or am I the only one who notices this?

reply to post by zorgon

So I am not sure why so many are having issues understanding this

The feeling is mutual. Here are the colors the Mars Express "sees":

Panchromatic (nm) 675±90 -Nadir, 2 stereo, 2 photometric
Near-IR (nm) 970±45
Red (nm) 750±20
Green (nm) 530±45
Blue (nm) 440±45

ESA

Here are the colors the Mars Rovers "see":

Left camera:
Empty slot (sharpest)
L1 750 nm (Near IR/ Red Stereo L)
L2 670 nm (Deep red - Geology)
L3 600 nm (CCD Pickup Red)
L4 530 nm (CCD Pickup Green)
L5 480 nm (CCD Pickup Blue)
L6 430 nm high pass (UV/ Blue Stereo L)
L7 440 nm + Solar Neutral Density

Right camera:
R1 430 nm high-pass (Near UV/ Blue Stereo R)
R2 750 nm (Near IR/ Red Stereo R)
R3 800 nm (Near IR - Geology)
R4 860 nm (IR - Geology)
R5 900 nm (IR - Geology)
R6 930 nm (Far IR - Geology)
R7 980 nm low pass (Far IR - Geology)
R8 880 nm + Solar Neutral Density

Pancam

This is what the human eye sees:
[atsimg]http://files.abovetopsecret.com/images/member/592022d04fde.jpg[/atsimg]

Now which set of sensors most closely reproduces what the human eye sees? If you said "Mars Express," you would be correct. The color images the ESA probe sends back are similar to the ones you would see on your television. These are not "true colors," they are images constructed by combining black and white images taken at different wavelengths. Most digital imaging works this way.

The NASA probe is sensitive to "colors" the human eye cannot see and is "blind" in some areas that humans can see. The designers of the probe were more interested in the regions we cannot see than the ones we can; they yield more important data for purely scientific purposes.

What color is the Martian sky? As you yourself have pointed out, Earth's sky is blue due to Rayleigh scattering, which scatters longer wavelengths the larger the particles (or molecules). Knowing the exact composition of the Martian atmosphere, we can calculate the scattering using the equations shown here. There is not enough coffee in the world for me to tackle those with a pocket calculator on a Sunday morning to settle something on ATS, so let's look at this less rigorously.

The Earth's atmosphere is mostly nitrogen, which consists of two nitrogen atoms "stuck together." A nitrogen atom has a radius of about 65 picometers (pm), which means a single molecule of N2 would be about 260pm across. The Martian atmosphere is mostly carbon dioxide, CO2. A carbon atom has a radius of 70 pm and an oxygen atom has a radius of 60 pm. (Here's the source for that.) From some angles, the CO2 molecule would have the same width as an N2 molecule, whereas from others it would have about 30% more surface area exposed. Based on this, I would suspect that the Martian atmosphere scatters a bit more red than the Earth's atmosphere.

Given that Mars' atmosphere is much thinner than Earth's, I would expect that it would be dark purple-blue overhead with a permanent reddish tinge around the horizon where the light passes through more of the atmosphere. Think twilight in Los Angeles.

So why, then, do NASA's pictures look the way they do? As ArMap has explained, the process used in creating the photos is additive, There is some light at every frequency. The blue filters used by the Rovers are at 430 nm and 480 nm. The human eye is most sensitive at 440 nm. The Rover is "playing" F and G together, rather than F#. Consequently, all the different colors start to add together to make white, favoring red because the IR filters tilt the sum in that direction.

So what is NASA "hiding?" Nothing. You can (and have) access all the raw images in their original format, which specifies which filter each one was taken with. You can then combine any image with any other image, assigning color values at your own discretion. You can generate any number of false color images in this way. The images we see in magazines and on the internet were created arbitrarily to approximate what the human eye would see. It is more of an art than a science, and NASA provides you with the materials to try it with. If you don't mind playing F and G together when you need an F#.

Those of you with 3D glasses i like to suggest this 3D film:

Its full HD 1080P in Stereo 3D footage of Mars. Some beautiful shots!

reply to post by zorgon


I really hate this planet.

As I said once in some thread, Phoenix had a good system to show the real colours (I sometimes use "real colours" ) in its robotic arm camera. It had three LEDs with precisely known wavelengths and filters that corresponded to those wavelengths, so using the images from that camera we get a view of how the Martian soil looks.

Unfortunately, the LEDs were only limited to a short range and they could not be used to illuminate the ground, only the soil on the scoop.





In the second image we can see that the photo was overexposed, but the colours are the same.

The following image is also from Phoenix, but from a different camera, and we can see that the colours are not that different.



Now that we know that the soil on the scoop shows the colours as closest to reality as possible, we can use that data to adjust the colours on the other photo, something I will leave for someone else to do.

is that rover still trucking across mars these days? i can't get a car with more that 40 mpg but that thing has be zooming around mars for years now.

reply to post by PonyoSon


Buy an electric car with solar panels.

Spirit is stuck, wheel caught. In the news, recently.....

Originally posted by zorgon

Originally posted by thesneakiod
Nice. Why though do NASA portray mars as a red planet?

Dunno

Same reason NASA colors Venus in a bright 'lava orange'?

The older viking images were correct... so why the change to 'NASA red'

edit on 18-11-2010 by zorgon because: No way am I filling this out

Zorgon, please forgive my ignorance on technical details in this subject.

I notice that that the Martian sky is blue in these two images..... is that normal?

I can't say I've noticed it any of the images from the last 15 years.

Edit: Check that Zorgon, I think the answer to this question is posted by DJW and ArMap higher up on this page.

Originally posted by ArMaP

You forgot to mention..
A) that you have said in the past that you believe the sky on Mars is blue. Gonna make me search for that?

B) you forgot to mention it was cloudy in that Phoenix picture. They also took some 'video'. That is why it looks grey

Originally posted by DJW001
Given that Mars' atmosphere is much thinner than Earth's, I would expect that it would be dark purple-blue overhead with a permanent reddish tinge around the horizon where the light passes through more of the atmosphere. Think twilight in Los Angeles.

Dark purple-blue Now that is interesting. I haven't seen any images that reflect that theory... hmmm

I like this better... color corrected



Images from the Hubble site

reply to post by ArMaP


AH yes here it is... when you created that colour image using the three filters...

You said... "PS: yes, that's a blue sky, before someone asks. "

From this thread 'Swamp Gas' on Mars? - The Green Fog
www.abovetopsecret.com...
From THIS post

Originally posted by ArMaP
OK, let's see if with some pictures I can explain better what I said before.

These are the photos used to create the colour version of that image.

For the red channel.


For the green channel, taken 143 seconds after.


For the blue channel, taken 135 seconds after the previous photo and 278 seconds after the first.


(All images are bigger than they appear here, click for full size)

In the first (red) photo there is nothing visible on that area where we can see the green dust (or whatever), but in the second photo (green) we can see what looks like a wide dust-devil. In the third photo we can see that the dust-devil has moved to the left, and looks fainter than in the previous photo, so it was probably loosing energy and disappearing at the time.

As anyone that knows how these RGB images are created knows, something that appears only in one of the images will appear in the final image as being of the colour for the channel in which the object was visible, so the joining of these three images should show a green dust-devil at the middle of the image and a fainter blue dust-devil to the left, and that is what we see.

This is the final result of using the above images to make a colour version.
(Click for full size)


Although faint, it's visible that there is a blue "mist" to the left of the green "swamp gas", as predicted by what was visible on the greyscale images.

That is why I think that this is really an image artefact and not a green dust, mist or gas, it's just the result of how these images are made.

PS: yes, that's a blue sky, before someone asks.

These are the radiometrically corrected images, they give much better looking results.

Nice picture from the Hubble wouldn't you say?

Originally posted by Krusty the Klown
I notice that that the Martian sky is blue in these two images..... is that normal?

I believe it is, yes.. on a clear day, not when a dust storm is active. In the second of the two Viking images you can even see a slight cloud cover.

I have many pictures of interesting clouds on Mars

September 11, 2008

An angry looking sky is captured in a movie clip consisting of 10 frames taken by the Surface Stereo Imager on NASA's Phoenix Mars Lander. The clip accelerates the motion. The images were take around 3 a.m. local solar time at the Phoenix site during Sol 95 (Aug. 30), the 95th Martian day since landing. The swirling clouds may be moving generally in a westward direction over the lander.

September 19, 2008

This sequence combines 32 images of clouds moving eastward across a Martian horizon. The Surface Stereo Imager on NASA's Phoenix Mars Lander took this set of images on Sept. 18, 2008, during early afternoon hours of the 113th Martian day of the mission. The view is toward the north. The actual elapsed time between the first image and the last image is nearly half an hour. The numbers inset at lower left are the elapsed time, in seconds, after the first image of the sequence. The particles in the clouds are water-ice, as in cirrus clouds on Earth.

www.thelivingmoon.com...


But that beautiful Hubble Telescope image "Spring Time on Mars" says it all I rest my case on that one, unless someone wants to tell me that Hubble LIES

reply to post by zorgon


From the discourse on this page it seems I am in way over my head here..

I think I have a little reading to do........