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Title: How Do Space Pictures Get So Pretty?
Source:
Slate
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Published: Sep 9, 2009
Author: Daniel Engber
Post Date: 2009-09-14 15:57:56 by Prefrontal Vortex
Keywords: None
Views: 324
Comments: 7
By Daniel Engber A picture taken by the Spitzer Space Telescope was released on Monday; the image, which depicts the birth of 100,000 stars in a far-away gas cloud, shows a splotchy shape in light red, set against a background of speckled blue-white stars and olive mist. How do these photographs get to be so pretty? Teams of specialists on the ground gussy them up for public consumption. Here's how it works: Telescopes like the Spitzer and the Hubble take black-and-white pictures using different filters to capture particular wavelengths of light. (The image released this week is a composite created from four shots of the same thing.) Then these pictures are sent back to Earth via the Deep Space Network, a set of large antennae set up around the world. For the Hubble telescope, the image files can be up to 70MB in size, with a resolution of 16.7 megapixels. Data is downloaded from the telescope at a speed comparable to that of a good Internet connection. Once the images are on the ground, scientists can look at them in the FITS ("Flexible Image Transport System") file format, a standard protocol used among astronomers. For analysis, most scientists use the data in this form—as grey-scale images representing light at different wavelengths. To create an image suitable for public viewing, the scientists send the FITS files over to a public outreach team. Specialists on the team—who tend to be astronomers with graduate degrees and a passion for graphics and photography—begin the process of converting the information into the images sent out in press releases. First, they put the image into a file format appropriate for media. That means that the data from the FITS files, which show a range of about 65,000 shades of grey, must be squeezed into a standard JPEG or TIFF file, with only 256 shades. This process is counterintuitively called "stretching" the data and must be done carefully to preserve important features and enhance details in the finished product. Then each grey-scale image is assigned a color. In reality, each shot already represents a color—the wavelength of light captured by the filter when that picture was taken. But in some cases the images represent colors that we wouldn't be able to see. (The Spitzer, for example, registers the infrared spectrum.) To create a composite image that has the full range of colors seen by the human eye, an astronomer picks one image and makes it red, picks another and makes it blue, and completes the set by coloring a third image green. When he overlays the three images, one on top of the other, they produce a full-color picture. (Televisions and computer monitors create color in the same way.) Sometimes the team assigns new colors even when the original pictures were taken in the visible spectrum. An object that would in real life comprise several indistinguishable shades of red might be represented to the public as the composite of three pictures in red, green, and blue. As a general rule, professional "visualizers" try to assign red to the image showing the longest wavelengths of light and blue to the one showing the shortest. (This parallels the relationship among the colors in the visible spectrum.) Finally, the colorized images are cropped, rotated to the most dramatic orientation, and cleaned of instrument errors and other unsightly blemishes. Most of this work is done in Photoshop, using a freely downloaded plug-in that allows users to convert from the FITS format. (The original telescope images are also available, so you can create your own color gas cloud picture at home.) Space pictures weren't always so pretty. David Malin, a scientist at a telescope facility in Australia, did the pioneering work in color visualization more than 20 years ago. He figured out how to use black-and-white photographic film and color filters to create full-color visualizations. The modern master of the field is Zoltan Levay, who works on images sent down from the Hubble.
Poster Comment: Worse than a Playboy centerfold.
How Do Space Pictures Get So Pretty?
Photoshop, of course.
Posted Wednesday, Sept. 9, 2009, at 4:56 PM ET
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#1. To: Prefrontal Vortex (#0)
Yeah but sure pretty to look at. Astronomy Picture of the Day Archive Once again, you miss the point. How is the view of uranus with your head up your ass?
http://kaygriggs.blogspot.com/ On freedom4um.com, Alex Jones is more dangerous than Henry Kissinger. May you live in interesting times.
Oh gee, I'm sorry. I forgot to personally attack you on this thread. You know I do that on thread after thread after thread.
Pointing out that you have your head up your ass isn't a personal attack. It is just being honest.
http://kaygriggs.blogspot.com/ On freedom4um.com, Alex Jones is more dangerous than Henry Kissinger. May you live in interesting times.
No. We use false colorization all the time to produce a better visual product. Basically every camera you use does the same thing; RGB filtering over a monochromatic CCD or MOS array. This in no way negates the "science" of said image. This is especially true for images outside of the very narrow band of EM our eyes have adapted to receive.
Ah! An honest merchant.
Anti-racism is code for white genocide. The call of "equality," is a siren song that can only mean the destruction of all that we cherish as being human. -- Murray Rothbard It is perfectly legitimate to assume that the races are different in their cognitive abilities and in their willpower and accordingly are unequally suited for the task of setting up societies, and that the better races are characterized in particular by their special ability to strengthen social bonds. -- Ludwig von Mises The photos are also long exposures. -------Worse than a Playboy centerfold.
"If, from the more wretched parts of the old world, we look at those which are in an advanced stage of improvement, we still find the greedy hand of government thrusting itself into every corner and crevice of industry, and grasping the spoil of the multitude. Invention is continually exercised, to furnish new pretenses for revenues and taxation. It watches prosperity as its prey and permits none to escape without tribute." --Thomas Paine, Rights of Man, 1791
#2. To: farmfriend (#1)
Yeah but sure pretty to look at.
#3. To: Clitora (#2)
Once again, you miss the point. How is the view of uranus with your head up your ass?
"If, from the more wretched parts of the old world, we look at those which are in an advanced stage of improvement, we still find the greedy hand of government thrusting itself into every corner and crevice of industry, and grasping the spoil of the multitude. Invention is continually exercised, to furnish new pretenses for revenues and taxation. It watches prosperity as its prey and permits none to escape without tribute." --Thomas Paine, Rights of Man, 1791
#4. To: farmfriend (#3)
#5. To: Prefrontal Vortex (#0)
Worse than a Playboy centerfold.
#6. To: Dr_Tron (#5)
a better visual product
#7. To: Prefrontal Vortex (#0)
In reality, not only would you not see the colors, you would not see much at all but a faint haze.
If you look at the Orion Nebula or Andromeda Galaxy with a telescope all you see it a gray hazy fluf.
However some things, like the Pleiades star cluster, look great in any telescope.
"Somewhere, something incredible is waiting to be known."
-Carl Sagan.
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