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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."
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.
If they wanted to take their revange they would have made it a link. Now, it is just text and most people don't like copy-pasting.
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
Slashdot Sig. version 0.1alpha. Use at your own risk.
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).
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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.
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!
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!.
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.