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Hubble image processing?

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#1 kyle528

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Posted 22 May 2019 - 06:48 PM

My step into astrophotography and the recent Hubble legacy field got me interested in just how the Hubble images are processed, who processes them, what kind of software is involved etc... However, all that my search has come up with is that the images are mono, many times mosaics, and a touch about assigning colors to channels. This is all very basic information to anyone who is familiar with astrophotography. I would like to read more about the more complex things we deal with in our post processing such as noise, color balance, things of that nature, things that an AP'er might be more interested in rather than someone who may know nothing about astrophotography fundamentals and may simply be wondering whether or not the images from Hubble are taken in color, or with a consumer camera etc... If anyone knows anything about this subject, or can point me to some good reading material please share!

 

Kyle



#2 OldManSky

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Posted 22 May 2019 - 06:55 PM

Did you come across this site in your searches?

 

http://hubblesite.or...age_processors/



#3 kyle528

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Posted 22 May 2019 - 07:23 PM

Did you come across this site in your searches?

 

http://hubblesite.or...age_processors/

Interesting, thank you!



#4 Berny

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Posted 22 May 2019 - 07:35 PM

Great link, thank you.



#5 ngc7319_20

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Posted 22 May 2019 - 08:40 PM

Virtually all Hubble science is done on monochromatic images, though often taken through multiple filters.  That is why your search mostly comes up with stuff about mono images.  Guys like Zolt Levay in the PR department will take these mono images and process them into the wonderful color images you often see.  They are primarily used for press releases, etc. "Color balance" etc. is left to the PR guys.  The link OldManSky gives is what you want.


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#6 TOMDEY

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Posted 22 May 2019 - 08:46 PM

I worked photogrammetry/astrometry/geodesy for decades, where planes and satellites image earth and space. Around 90% of the effort involves ~boring~ quantitative stuff like pinpointing the locations/coordinates of events, features of interest on the earth, planets, moons, celestial sphere etc. --- as accurately as possible in space and time. The kinda stuff that has utilitarian links, like your Garmin telling you to turn left exactly here and your plane to avoid the one below you, Mars lander to touch down exactly there. For the observational astrophysics, the image data and display renditions are generally not pretty... but are very very quantitative.

 

The stuff processed for Press Releases --- greatest value is wowing the public with celestial fireworks. The most colorful, contrasty, brilliant, dynamic renditions carry the show. Nothing wrong with that, nothing at all! After all, it is our tax dollars that fund these programs, and we want to be entertained first... and maybe even educated.

 

We here, on Cloudy Nights, are much more interested in the science than is the ~general public~ but still want to make our pictures as pretty as possible.

 

Closely Related:

Occasional threads here, discussing whether it makes sense to save or purge the huge amount of ~raw data~ that went into producing that one final image. The scientific answer is to save all the original data. But, as 99% of us can attest... 99% of the data never gets revisited.

 

I know that doesn't answer your question... but that's what the scientists deal with. Those doing serious quantitative work would request the best-calibrated data that NASA has to offer, and take it from there. The term used to be "Ground Truth" --- for astronomy it probably is something like "Space Truth" ?   Tom



#7 Alex McConahay

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Posted 22 May 2019 - 09:00 PM

One of the interesting things about Hubble data is that each pixel on each camera has a precise history. The scientists know exactly the characteristics of how it reacts to each spectrum, how it is hotter or colder than it should be, and all that. It's really detailed. For every single pixel in every single camera. 

 

Alex



#8 fewayne

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Posted 23 May 2019 - 06:26 PM

There's a very accomplished astrophotographer who hangs out at Digital Photography Review's astro forums, he has recently had to give up field astro work due to health issues but he's going through the Hubble catalog and doing his own processing on their data. Fun guy to talk to, just beautiful work. He'd be an interesting chat if you were thinking about exploring by doing.




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