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Brown Dust - A few pointers

patrickgilliland
19 Nov, 2015 15:27
How do you get brown dust in dark nebula images?
I have been asked this question a few times (Including today by Matt Herbik) and as there is no magic to it thought I would share a few pointers and this forum seemed like the ideal location.

The key is the RGB data and ensuring it is well calibrated.
With the calibrated, cosmetic corrected and ABE/DBE frames then.
Process your RGB separate to Lum data.
When processing and object including where brown ensure images are aligned before you merge - linerfit or similar.
I then combine using channelcombination.
I then run SCNR green at about .5-.7 to shift slightly in the red area of the colour spectrum.  At this point I will apply colourcalibration and background neutralisation.  However if one of them is to aggressive I will omit purely from visual inspection.  I will then manually review the RGB histogram and adjust.
NB: I often prefer aggregated previews for calibration than one isolated one, but on occasions running with no previews works very well.  Experiment and you will find the right result.
At this point I would then run a DBE with normalise selected to ensure gradients have been corrected.
I then use the colour saturation tool to boost the colours (lots of small adjustments)- you can run on entire image then selected areas using various techniques such as range and star masks.
I will typically boost the colours just below what I think is the maximum acceptable - you can always add more colour after lum combination.
Once saturation is adjusted I would check colourcal and background neutralisation again finally finishing with a manual review/adjustment of the histogram.
There is no hard and fast method of when to run each tool - watch the data and work with it.  If something is not as desired undo and try something else.

I then would merge with LRGBcombo using processed lum frame.  I would then repeat colour process again at start of LRGB processing and if required towards end of LRGB full processing.

Remember also lost of little tweaks often provide more control and 'effect' than one massive one, it will  offer more control and provide a more natural adjustment.

If you follow these rules as an outline you should find your dust will be browner - in fact sometimes it will be too brown and desaturation can be required.

Hope that helps - of course there is always more detail than this but as a guide I think this should help.

Paddy
Edited 19 Nov, 2015 15:28
mattherbik
19 Nov, 2015 17:51
Thanks Paddy. I will give it a try on my next image with dust lanes as I previously said all mine seem to appear black or dark areas not colorful (brown)who knows still may be due to my being new to this thing. Lots to learn! Wish you all clear skies.
Edited 19 Nov, 2015 17:51
northisup2
20 Nov, 2015 15:01
Thanks for this information Paddy . I  have just started doing some  RGB images   from my backyard red zone   smile   hopefully I can get some decent results .
                                                                                 John
patrickgilliland
20 Nov, 2015 15:08
John Leader
Thanks for this information Paddy
Welcome - see how it goes and ping over any queries etc

Paddy
uranus7
21 Nov, 2015 19:34
Thank you Paddy for the useful  tips. I'll use them  for sure, the next future.    smile

Gabriel
patrickgilliland
21 Nov, 2015 19:39
Welcome Gabriel, hope it is useful. Paddy
chrischarlesjax
23 Nov, 2015 13:50
What do you mean by ABE/DBE? LOL, sorry. smile
Edited 23 Nov, 2015 13:51
patrickgilliland
23 Nov, 2015 13:54
(A)utomatic or (D)ynamic background extraction.
jcbeyer
28 Jul, 2016 20:19
Thank you for the information Paddy.  I had not seen this post but will use it in the future.  I recently reprocessed an image of the Orion nebula I had taken December 2015 being the first DSO image I had ever acquired.  The reprocessing was in part inspired by the posting of your winter mosaic that I had another try at the data.   I was amazed at the visual information I was able to pull out and using your mosaic as a visual template was able to bring more of the brown dust out that I had completely missed on the first try at processing.  Your mosaic is a striking piece of technical work and truly a piece of art!  Best regards, Joe
Edited 28 Jul, 2016 20:20
 
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