To black sky or not to black sky.

[Mac]

Right here's to opening a heated debate about the background, or not.

Why do people object to very black backgrounds on images?

My personal view is as follows.

if you were to rise above the atmosphere there would be no diffraction of light caused by the atmosphere.
No sky glow caused by light pollution.

Our sun would just be a complete circle ok a bright circle but around the sun would be blackness

The only light would be from the stars / nebula in our own galaxy and then further galaxies, ect.

The space in between would be void of light and therefore black.

So why is there a huge dislike to the nice inky black backgrounds?

Mac.

[mickw]

I don't think the issue is with a black background, I think it's to do with forcing the intensity of black background to the detriment of any background nebulosity or other faint stuff

[Rocket Pooch]

There's no debate really, some areas of the sky AKA Cygnus are just not black because of all the stuff there, whereas parts of the Plough are quite black.

Also I really doubt any of space appart from Black Holes is actually black anyway, or else where does all the light go.

Oh yes and lets not discuss relavistic speeds from non relavistic galaxies travelling away from each other, or it will hurt....

[PhilB]

I guess that it also depends on what you're processing for. Pulling up detail in the main subject might well mean that secondary objects, like the background, end up with a misprocessed feel to them.

[RobertM]

misprocessed

Now that's an interesting imaging term...

[Fay]

Well, you can process the main subject without touching the background, but as long as the histogram is not clipped I think it is a personal preference     

[RobertM]

In other words it's all subjective which to some is misprocessed.  If we were to process them scientifically then the histogram would cover the whole range of values, there would be no stretching of the image and the world would be a duller place

I don't think there will be anything completely black out there until the universe has reached 0 kelvin.  What we have is variations of brightness all dependent on what's out there to reflect the light, granted most of it looks black because we haven't got any instrument that sensitive but it's there none the less.

Does anyone know that for the particular spot they're imaging the background should be black/milky/otherwise?

I don't mind inky black backgrounds but if the black point obscures some signal then surely it's set too high.

Robert

[PhilB]

It all rather depends on what you're tying to look at, specific features or a more general view showing as many aspects as possible. If you had an interest in a galaxy's dust lanes for example, you could adjust the image for the best possible view of these, even using false colour to tease out detail. Perhaps we should replace the term "misprocessed" with a more general but rather cumbersome  "not representative of the image as we're used to seeing it".

[MarkS]

All images contain background noise.  To obtain an inky black background, the black point has to be set above this level of noise (or heavy noise reduction applied).  However in areas of faint nebulosity, the signal itself barely rises above the noise level.  But in those areas, the brain actually does an excellent job of distinguishing between the faint nebula and the noisy background - it sees the nebulosity and "ignores" the noise - just like what happens when you look at a grainy photograph.  Grainy photographs have an artistic merit in their own right.  If the black level is set at a point where the noise disappears then some faint nebulosity disappears with it and the brain never gets a chance to "do its stuff" and some of the subjective pleasure of the appreciation of the "work of art" disappears with it.

I also don't like the heavy noise reduction that is applied by some astrophotographers - to my mind it results in a very "plastic" and artificial appearance.  Plenty of examples of this on APOD. 

Leave the noise in the iamge and let the brain decide!

Mark