Why do NASA use freaking filters all the time when they take pictures?

Question

ty dave nice point

Answer 1

Taking images in space is not for the purpose of making a pretty picture.  Its purpose is for scientific investigation.  Filers are used to capture specific wavelengths of light to allow for detailed measurement.  

Answer 2

The point of NASA satellites and robots are not to take pretty pictures.  That's just a bonus.  The point is to get scientific information about the things you're taking pictures of.  The filters can tell us a lot of information - the filter which a star is brightest in can tell us it's approximate size, temperature, age, and even what it's made of in some cases.  That's why we use filters - for the science.

Answer 3

I'm having a Deja Vu moment.

Your 10 megapixel camera does not take red, green and blue colors at each of those points. It only takes red, green or blue. The other two colors are interpolated from neighbors that happen to be those colors.  This does not work for science.

In particular, you can't then use a hydrogen alpha filter, or a sulfur 2 filter, or a methane filter to learn something interesting.  You'd be stuck with whatever tiny little filters are in your camera.

Amateur astrophographers mostly use black and white cameras with filters too.  At the high end, they use three or four telescopes at the same time, each with it's own filter.

Answer 4

Instead of sending a balky and expensive color camera to deep space, sometimes the Nasa folks send a black and white camera, with red, blue and green filters they can select at will.  When a scence is photographed through each one of the filters and then the three images combined, a true color image is produced. Or is it red, blue, and yellow?  Anyway, each of the filters produces a side effect...because each one yields an image of a specific wavelength (more specifically, a wavelength is taken away) certain properties of a material or object can be discerned.

Another reason filters are used is simply to reduce glare or reflections.  In outer space shadows are not diffuse like they are here on Earth because there is no atmosphere to diffuse them.  Filters are used to reduce the effect of the resulting glare and high contrast between light and dark.

Answer 5

I think it's just to remove unwanted light from viewing all the stars/galaxies etc... just to make the picture nicer.

Answer 6

David A is on the right track.

Scientific photography combines images taken at several different wavelengths.  So a space camera is a simple black and white camera with an arrangement of filters at all different wavelengths, including many non-visible wavelengths.  Filters have different bandwidths too; some admit only very narrow bands of light, corresponding to specific wavelengths that are of interest to planetary scientists.

To get a true or near-true color image, you combine photographs taken with red, green, and blue filters and allow each channel to drive a standard RGB display.

But most of the actual science is done algorithmically in the computer.  You take several frames at several wavelengths, including the non-visible ones, and produce an intensity map that makes each pixel value depend on formulas that combine the values of that pixel in each wavelength.  So an image algorithm might say, "color brightly the pixels that radiate strongly in this particular blue, but not in the infrared."  This is a crude form of computational spectrometry that allows scientists to identify minerals and things in images.