June 7, 2020

Astro-Image Processing: How Far is Too Far?

NOT a fake…

Image credit: Dave Dickinson

Alright. We’re going to touch on a hot button issue in astrophotography on this week’s soapbox rant. After years of watching the discussion come ’round, we’re going to add our two cents. When it comes to post-processing, how far is too far? When is an image no longer an accurate rendition of reality?

First, a confession. We’re a casual dabbler in the field of astrophotography. We do occasional wide field shots with the DSLR mounted on a portable tripod, and we have some background with planetary imaging with homemade converted webcams. Don’t worry, we won’t go very far into the arcane art of wavelets, historograms, or fields, flat and dark. We are in awe of those who painstakingly create awesome vistas of difficult targets. Hey, in astronomy and the universe, we can all afford to ‘level-up.’

And overall, we think that the ready availability of DSLRs capable of astrophotography is a great thing. Just about anybody can do basic star trail imaging, right out of the box. While some say it lowers the bar for entry, we like to say hey, great, another neophyte is won over to the wonders of the night sky.

The problem comes when we’re tempted to push belief, all in the name of an amazing image. If it looks too good to be true, it probably is. This came to a head recently, when ‘ISS Saturn transit-gate‘ exposed the image as a fraud. Yes, we’ll admit that we hit the re-tweet button too. Our gut reaction was ‘wow, that’s a very improbable capture…’ but the creator explained in great and accurate detail how it could be done, and we thought ‘OK, improbable… but not impossible…’

Of course, there are images routinely shared that are flagrant fakes. These are easily dismissed. And at the other end of the spectrum, some would accuse NASA of executing a ‘cover-up’ by using any image processing at all. False color is kind of a misleading term, and pushing an image to highlight a real scientific phenomenon is certainly fair game. None of us have X-ray vision (sorry, Superman) and the universe operates far beyond the sliver of visible light we’re all familiar with.

And is it a fair representation to show faint aurora in vibrant splashy color from a time exposure? It’s kind of a rite of passage in astronomy, that moment when we first find the Andromeda galaxy or the Orion nebula and realize that the real universe is actually a very gray place, far removed from vibrant Hubble pics or magazine images.

You see a pattern here, and its all about disclosure. Stacking images, processing and frame aligning are all a way to get at elusive detail that’s actually there. Evolution gave our MK-1 eyeballs just water and jelly to work with, a pretty cruddy optical configuration ill-equipped to see the delicate wonder of the universe.

If you’ve compiled a mosaic to depict a concept or idea, say so. Show off your failures as well as your successes. Good astrophotographers are open with their techniques and processes and are always willing to help beginners out. And we’ll let you in on another secret: please forgo the enormous logos and watermarks covering half the image. No one’s successfully copyrighted the Universe, and again, you’ll note the elite astrophotographers don’t do it.

And finally, don’t get discouraged. We’re never ashamed of sharing a back-of-the-camera smartphone shot, warts and all. We feel its important to share the process, and show folks all those steps (and sometimes missteps) in between.

And don’t forget: the Sky is waiting!


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