Slashdot Mirror
The Real Reason why Spirit Only Sees Red
use_compress writes To produce a color photograph, the rover's panoramic camera takes three black-and-white images of a scene, once with a red filter, once with a green filter and once with a blue filter. Each is then tinted with the color of the filter, and the three are combined into a color image.
In assembling the Spirit photographs, however, the scientists used an image taken with an infrared filter, not the red filter (NYTimes, Free Registration Required). Some blue pigments like the cobalt in the rover color chip also emit this longer-wavelength light, which is not visible to the human eye."
The reason being that the science gets better results using th e IR filter than if the red filter were used... At the moment, despite great public interest, the science is more important... that IS what it's there for....
Simon
Physicists get Hadrons!
'Aha! So that's why they don't see little green men...' - at last, the dream of aliens living on Mars is alive again.
How the Red Planet Came Down With the Pink Blues
They mention slashdot.org by name.
Could this be some sort of revenge?
Can anyone explain why 3 separate B/W images are taken? If it is because of bandwidth... 3 grayscale images weights (more or less) like one color image ... so why B/W and filters?
------- The last Sig. got fired.
It's a good job the pictures aren't coming back with a blue tint, or lynch mobs would be turning up at NASA HQ.
If I seem short sighted, it is because I stand on the shoulders of midgets
On the panoramic picture: We goofed. It should not have been that red.
The other photographs are taken with the infa-red instead of visible red filter. Iron dominated the visible red spectrum. To allow a better analysis of the compounds found infa-red light is used instead.
<joke>No conspiracy here. Move on.</joke>
the_crowbarHave you read the Moderator Guidelines
Reminds me of the Gameboy Camera Color Project: http://www.ruleofthirds.com/gameboy/
They release all the individual raw pictures on the mars rovers website. You are free to composite them yourself.
The engineers are focusing on the filters that return good science.
ALL data IS actually released.
/. stories), but several people have taken the raw data and composed their own versions of the colour photos.
:)
Cant remember links from the top of my head(Search older
AFAIR the things is a bit more complicated though - the cameras have 7 different filters, which have quite a bit of overlap, and doesnt peak at frequencies of light that directly could be used in an RGB image - so some fiddling is requered.
And TBH - I think its perfectly fine NASA doesn't focus on producing "correct" images if it doesn't mean better science!
The human eye's color vision is a poor scientific instrument. It can be easily fooled.
Mea navis aericumbens anguillis abundat
Quite possibly because it wouldn't survive the conditions on Mars. Or on the way there. Try deep-freezing your digital camera, then put it in a vacuum chamber, then in a really dusty sandbox, and finally subject it to a potentially lethal (for a human) dose of radiation, and see if it still works. Oh, and don't forget simulating the landing; heat it, vibrate it, and toss it on the ground.
Disclaimer: I wasn't there. I don't know exactly how the poor thing was treated. I'm not a member of the PETC (People for the Ethical Treatment of Cameras).
This signature is not in the public domain.
Since nobody else has yet, the registration free partner link: http://www.nytimes.com/2004/02/10/science/space/10 COLO.html?ex=1076994000&en=a6c9abc6b269678b&ei=506 2&partner=SL4SHD0T
because that 4 megapixel camera from comp usa is a total piece of crap compared to the 1 megapixel B&W camera on the rover.
I have a old 2 megapixel digital camera that will beat the Best 4-6 megapixel consumer camera you can buy today. because of optics and the design of the CCD. (mine is a TRUE 2 megapixel whereas almost ALL camera's today sold as a 4 megapixel are really a 1.3 megapixel camera as you need 3 pixels for each photographed pixel.. (I.E. one for red,green and blue.)) plus the resolution of each color captured is vastly different, green usually being the best resolution while blue suffer's the most..
Nasa is not about to send the really low grade crap that is available to the cunsumer to another planet. they sent the real deal.
I suggest you actually learn about digital photography and why consumer grade "cameras" are utter junk.
Do not look at laser with remaining good eye.
A material can emit light at various wavelengths, and at wavelengths quite different than that which it reflects, which is what you most commonly see in the visible range. It's quite possible for something to reflect blue light and emit light at wavelengths longer than the visible range.
I'd imagine because the blue colour corresponds to an electron transition in the d-orbital whereas the IR corresponds to a different transition or more likely to a change in mode of molecular vibration.
One of the few things I remember from my chemistry degree was that many pigments are far brighter in the UV region since the "normal" colour corresponds to a forbidden transition - i.e. one that involves a change of spin as well as change of orbital.
I do hope that wasn't a rhetorical question...
Boring Old Fart (40, married, 3 kids...er no...make that 49, married, 3 grown up kids...it's been a long time)
My site was one of the past ones featured on Slashdot.
Unfortunately, all data isn't released. There is not radiometric data or pointing data for pictures, spectrometer data, etc.
And NASA puts a hold on images they plan to use later for press conferences-- e.g. the individual PanCam pictures of the parachute and backshell weren't released. This goes directly against the promises they made pre-mission.
The martian crab http://homepage.mac.com/thomasmcgee/ I know, I know, go ahead, mod me off topic. The truth is out there. Would anyone like to start a petition that requests NASA to try to get one more photo of this thing before they drive away?
I don't know if my camera has a cheap filter or no filter at all, but it is more sensitive to infared than the naked eye. The easiest way to see this is to point a remote control at the camera, hold down a button and snap a picture. In the picture you can see the little bulb in the remote all lit up, even though it is invisble to the naked eye.
I read the internet for the articles.
I've often wondered exactly how rigid the "400-700nm is visible" rule applies. We know that some animals can see infra-red and ultra-violet. But just how well-defined is the wavelength range for human beings? I mean, our bodies are different shapes and sizes, our voices have different pitches, our ears have varying ranges, some of us are allergic to certain substances that others are not ..... but has anyone ever investigated the phenomenon of what wavelengths humans can see? Is it a person-to-person variable, or is it constant for everyone? Can some people see IR, red and green, for instance, instead of red, green and blue? Or green, blue and UV, for that matter ..... and what would it look like?
Je fume. Tu fumes. Nous fûmes!
When you take a look at what this old-tech can really do, it's quite astounding.
The Library of Congress has an exhibition of pre-WWI (that's World War I) *color* photos of Russia shot using the exact same process. Since this was a while before any practical color photo printing processes the photographer built a "magic lantern" for "optical color projections."
Props to Bolo Boffin for the link.
Read this and this. These are from the NASA Rover site and they explain it all.
- - - - - - - - - - -
I am a programmer. I am paid to produce syntax not grammar. Deal with it.
I would guess (based on my experience with other NASA data archives) that the full scientific data are not being released until they've been calibrated, at which point they'll probably end up in the Planetary Data System It's also possible that the Principle Investigators (who are affiliated with Cornell, not NASA) have exclusive use of the data for some period of time. Scientists are often very reluctant to share data until they're happy with it. Whether this is good public policy (since the data was all paid for by the US public) or good science is open to debate, but it's certainly not a conspiracy.
In the case of the more dramatic images, Public Affairs is almost certainly embargoing the images so the press release will (in theory) have more impact. If you really want the data you can always try a Freedom of Information Act request.
Prokudin-Gorskii travelled Russia taking color photos about a hundred years ago, a time when there was no color films. He used to take 3 pictures, one after another, each one with a different filter. He then projected the three together to get a color picture. Similar to Spirit but in a very, very old fashion.
so, i threw this one together the other day, is it anywhere close do you guys reckon?
Spirit-pano-rgb-compose.jpg
Software Freedom Day!.
Pioneer 10 and 11, which both flew past Jupiter in the mid 70's, used only a red and blue-green filter IIRC. They used these two colors to approximate full-color images based on earth-bound images. I don't remember anybody fussing about it back then. A disclaimer of sorts was usually in the more technical articles, but many articles said nothing about it.
Table-ized A.I.
If you use an infrared filter like the L2 filter on Sprit's Pancam, you get data that represents only things which reflect or emit light in that particular region of the spectrum. Anything that emits light ONLY in the red will be absent from the data set. It is possible for something that appears as a fairly monochromatic red to be entirely invisible. How can you use Photoshop to put back something that is invisible? You cannot.
You can adjust an individual colour in the image using a reference image taken with the appropriate filters, and that colour will then appear correct. Other colours, however, will remain distorted.
Worse, you cannot possibly know the emission/reflectivity spectrum of things on Mars, so any image you produce that appears to show the sundial colour chips correctly may distort terribly the Mars components of the image. It is not really very interesting to see a colour corrected photo of the sundial, is it? We could have achieved that without sending the rover all the way to Mars.
Nope, using a relatively narrow-band-pass infrared filter like the L2 simply leaves out information about the red part of the spectrum, and extrapolation only goes so far in recreating that data. Non-linear data - discontinuities within the missing portion of the spectrum - are simply gone, never to be retrieved.
Also, NASA is lying. Perhaps 'lying' is too strong a word, but they are either deceiving us or they are operating under a serious misconception.
"We just made a mistake," said Dr. James F. Bell III, the lead scientist for the camera. "It's really just a mess-up." Well, NASA claims to be releasing the raw data from Spirit on its web site, but the raw data does not contain any image sets for the panoramas taken with the L4, L5, L6 filters. They have almost never used the L4 filter.
So either the "mess up" is that they have forgotten to use the L4 filter from day one (unlikely, since each photograph taken presents another opportunity to switch to the L4) or that they have L4 images but they are not releasing them, in which case they really are not releasing the raw data.
The argument about the L2 being better for science is bogus. There's no way that NASA scientists are doing serious mineral analysis with a pretty, stitched-together wide view panorama. That's just rubbish. they would be looking at detail images, and possibly comparing between detail-level images. The panoramas are strictly for public consumption, and maybe office posters at JPL.
It's probably not a conspiracy, but it is a mystery.