How False Color Astronomy Works 28
StartsWithABang writes: When you look out at the nebulae in the night sky — especially if you're seeing them with your eye through a telescope for the first time — you might be in for a big surprise. These faint, fuzzy, extended objects are far dimmer, sparser and more cloud-like than almost anyone expects. Yet thanks to some incredible image processing, assigning colors to different wavelengths and adjusting the contrast, we can make out detailed structures beyond what even your aided eye could ever hope to perceive. Here's how the magic happens, and what it teaches us.
Colour My World (Score:1)
Really crappy article (Score:5, Informative)
I know I should've expected it given it's on medium, and it's been submitted to /. by its own author, but that's a really bad article. It's full of irrelevant details, stupid comparisons and misleading crap. I understand the concept of "science evangelism" but could you please do it without acting like a total buffoon?
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Next up; an article explaining how these flat, 2D picture are not a true representation of what three-dimensional galaxies really look like in reallity.
News for nerds? (Score:5, Informative)
They are more art than science, providing an illusion of reality.
Nope, they are coded with the relation color = abundance of atomic component. Colors are a stimulus, they do not exist outside of all of our brains. What is real is the wavelength, and that, for instance, the transition of an electron from the 3rd to 2nd layer of the structure of the Hydrogen atom will emit a photon at 656nm, which we call red.
One disadvantage of the FITS format is that raw images typically need to be manipulated to show anything.
Nothing to do with the FITS format. That's the same type of information all RAW formats have : unprocessed data, as close as possible to the signal coming from the sensor after quantization, with ideally no processing, offset or other adjustments performed.
It made for great imagery, but wasn’t a true representation of how Jupiter looks.
Our vision is also subjective, it permanently adapt to lightning and ambient color conditions. There is no such thing as a true image representation. Especially in the mentioned case (a magazine), where it is desirable to have an image which pops the eye rather than a blob of washed out colors.
So what's the news here?
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Also FITS may have ASCII headers, but it can also contain binary data.
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Its probably also worth noting that due to doppler redshifts the colors we see from space are usually not the real colors anyway. When it comes to "reality", our eyes don't see it, at least with space.
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Our vision is also subjective, it permanently adapt to lightning and ambient color conditions. There is no such thing as a true image representation. Especially in the mentioned case (a magazine), where it is desirable to have an image which pops the eye rather than a blob of washed out colors.
So what's the news here?
Are you saying that tourist photos of cities oversaturate the colors to make it look more impressive than it really is? Say it ain't so!
(To observe this effect if you live in a big city, just go look at tourist material for your own city... and then wonder if it's the same place you've been living all this time.)
Process with moderation. Inform the viewer. (Score:2, Interesting)
In the amateur astrophotography community some people image-process to death by using brush tools to selectively enhance specific features. An example: "Paint" a galaxy with a brush tool to make it stand out from the background. In my humble opinion, this is unacceptable. One other example: Wrong color balance in wide-field Milky Way shots, resulting in blue night skies. The night sky can't be blue for any aesthetic reason. At least, inform your viewers that your images are (heavy) processed.
Thierry Legault [astrophoto.fr]
Re: Process with moderation. Inform the viewer. (Score:3)
FROM THE OUTSIDE, IT'S BLUE.
(Yes, that needs to be in all caps.)
I'd like to see comparisons (Score:2)
While the images are certainly pretty, and also certainly scientifically useful, nonscientists generally expect to look at a color image and see what they'd see if they were looking at it out the window.
Instead of showing us "image" vs "enhanced image" of the crab nebula, I'd rather that they took some pictures of things we see regularly - a person, for example - and show us the results of the SAME image-processing on these familiar images, so we could judge if the 'enhancement' is trivial or substantially
If you want to know how it works, simple answer (Score:1)
It's done the same way as real colour is done: you assign a colour to a frequency of light and make the brightness of the colour depend on intensity.
Really. That's all your eye does too. And photographic emulsion or CCD cameras.
They respond with a certain efficiency to a range of light frequencies and overlap their resposes. The end result we call "red" "green" and "blue" by convention. Mixing the intensity then produces a colour impression.
No different here. Just the response curves are different and exten
You understand the merits of this (Score:2)
Mars pictures often three versions (Score:2)
2) "True color" processing to match the colors on a reference image painted on a probe wall. Took a while to confirm the Martian sky and sunsets are different colors than Earth counterparts.
3) "Enhanced color" contrast jacked up to reveal more details like cracks and nodules.
Enhanced images have always had a downside (Score:2)
The use of enhanced images, illustrations, artists' conceptions, and diagrams in science education cuts both ways.
Even when I was growing up (in the 1950s) my first impressions of astronomy were formed by illustrations of the solar system--shown from a point of view outside the system, with the orbits displayed as brightly colored, ellipses, and the planets on a scale a thousand times larger than the scale of the orbits.
Something like this helps the child understand what it is that astronomers discovered, a
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Even when I was growing up (in the 1950s) my first impressions of astronomy were formed by illustrations of the solar system--shown from a point of view outside the system, with the orbits displayed as brightly colored, ellipses ...
Now that would be cool; standing at a point where the ecliptic plane is right overhead, and seeing a bright red ribbon erupting from the ground, extending straight up as far as the eye can see. The eruption point would move at 1600 km/h and the ribbon itself would move up at 29 km/s. I'm so disappointed this doesn't happen :-)