The Real Reason why Spirit Only Sees Red 273
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."
Why b/w & filter? (Score:5, Interesting)
Re:prepare the servers for a nytimes-dotting... (Score:5, Interesting)
But they mention that "As Mars buffs have pointed out in recent weeks on Web sites like Slashdot.org" , i wonder if they read Slashdot because they like it or just to see why an ungodly amount of refferer logs says: slashdot.org
Why don't they release the RGB too? (Score:2, Interesting)
Blue? Infrared? (Score:2, Interesting)
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."
If it's a *blue* pigment, why does it emit a *longer* (i.e. infrared) wavelength?
Re:Why don't they... (Score:5, Interesting)
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).
Re:Why don't they... (Score:4, Interesting)
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.
before shooting comments off the hip about IR (Score:2, Interesting)
most of the digital cameras on the market dont have countermeasures to prevent IR exposures, so feel free to experiment with various infrared-transmitting, deep red and light red filters.
from my non-scientific experience, ultraviolet photos of rocks is more interesting than infrared.
But what is this thing? (Score:5, Interesting)
Re:before shooting comments off the hip about IR (Score:4, Interesting)
Re:But what is this thing? (Score:1, Interesting)
Much better images here: www.rense.com [rense.com]
I know Rense is a bit of a tin-foil hat site, but NASA have been strangely silent on this.
The original NASA picture is at: marsrovers.jpl.nasa.gov [large file] [nasa.gov]
Even the mainstream press are (deliberately?) ignoring it.
I don't think it's debris from the lander.
I've often wondered (Score:3, Interesting)
Re:Why b/w & filter? (Score:1, Interesting)
Imagine NASA wants to see a spectra composed of red, green, blue, two kinds of infrared and two kinds of ultraviolet light. So that makes 7 "pixels-per-pixel" meaning you get 1/7 of the resolution. Not very good from a scientific point of view.
color problems on ordinary digital cameras (Score:3, Interesting)
As a hobby and as income, I make borosilicate lampwork beads and sell them on ebay. This requires me to take digital pictures of my beads, which I do with a Nikon Coolpix 885.
Every once in a while I run into a color combination that simply cannot be photographed correctly. One bead set I have looks brown/butterscotch/caramel to the eye, but when photographed using that particular camera, some of the brown features in the bead come out electric red.
Re:Why not just give NEW pictures! (Score:3, Interesting)
JPL says (Score:3, Interesting)
Re:I've often wondered (Score:5, Interesting)
Interestingly the work of Claude Monet demonstrates this. Starting with his early work which is clear and in the normal colour range, then he develops cataracts and his work is more undefined swirls of colour, often dark and dim. Then he has cataract surgery and the new work is bright and vibrant, but with a deep purple/blue hue to many things because of the now increased presence of UV light in his vision.
Re:Why not just give NEW pictures! (Score:3, Interesting)
Spirit-pano-rgb-compose.jpg [sunsite.dk]
Re:Why b/w & filter? (Score:3, Interesting)
On a slightly related note, a Russian photographer named Sergei Mikhailovich Prokudin-Gorskii pioneered this technique of obtaining color images using colored filters and monochromatic film in the early 1900's. He actually built his own camera with three vertically-oriented lenses, each with a red, green or blue filter. The camera took the three pictures at the same time, but some interesting distortions come through because of the slight differences in paralax.
http://www.loc.gov/exhibits/empire/ [loc.gov]This was mentioned here on /. some time ago, but if you haven't seen his photos, they are definitely worth checking out.
Umm... (Score:3, Interesting)
But a comparison of the Mars Pathfinder images against the MER images shows that the colors in the MER images are too red. In the MPF images the rocks aren't all the same color.
It's pretty obvious that NASA's been doing a lot of Photoshopping on these images. While some Photoshop'ing is necessary (to merge the 3 grayscale images and to eliminate the seams in the panoramic images), I think they're overdoing it this time. I can't find the link right now, but there's one image in particular where it's blatantly obvious that they've replaced the sky with a single, solid color (you can see jaggies along the horizon in the high-resolution version).
I'm not trying to be all conspiracy theorist or anything. I certainly don't think they're faking the landings, nor do I think the Martian sky is bright blue as some have suggested.
Re:Why not just give NEW pictures! (Score:5, Interesting)
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.
And you are right. (Score:2, Interesting)
I have it on pretty good authority that it is part of the airbag.
Just wait for more images from MER-B (Opportunity). You're about to see some really cool stuff in the next few days. No Martian crabs or bunnies, I'm afraid, but still some awesome stuff.
Pancam Details/Specs (Score:3, Interesting)
- Info (src: Athena) [cornell.edu]
- Tech Briefing (PDF 52 KB) [cornell.edu]
- Info (src: Planetary Society) [planetary.org]
- Info (src: NASA) [nasa.gov]
- Info (src: Caves of Mars) [highmars.org].
- Filter Specs [ominous-valve.com]
(showing approximate color swatches in browser).
--For news, status, updates, scientific info, images, video, and more, check out:
(AXCH) 2004 Mars Exploration Rovers - News, Status, Technical Info, History [axonchisel.net].
Re:Why b/w & filter? (Score:3, Interesting)
IR filters are easy to obtain. But if you want decent exposure times, you'll need to remove the hot mirror first, and replace it with plain glass. Most people don't want to do that to their digital cameras. But since I'm an idiot, I've done exactly that. You can see the results here [soupisgoodfood.net]. The lack of IR blocking filter means I can take IR pics without a tripod in good light.
IR is interesting. I have quite a few black cloths that come out bright white, while other black cloths still come out black.
Dust? (Score:3, Interesting)
Hm. I'm no meteorologist, but I wasn't seeing any evidence of a dusty atmosphere in any of those rover images. --Details at distance seemed as clear as near objects. There's WAY more crap in Earth's much more robust atmosphere, and we get plenty of white light.
-FL