This is a collaboration project with Uwe Deuterman, who imaged the target for this dataset.  You can find his posting of this target along with his equipment used and acquisition details here:
Uwe Deuterman Sh2-170: https://astrob.in/nalx56/0/

Uwe and I have been exchanging ideas, information, and opinions on our individual Astrobin postings/projects for just over a year now.  It was he that finally "pushed" me over the edge into the dark side of monochrome imaging.  

Uwe imaged Sh2-170 a few weeks ago and posted his image.  With his posting, he expressed his dissatisfaction with the result compared to what he had in mind to achieve.  We exchanged some ideas and suggestions.  Those discussions carried over into a project I was having some issues with (IC63), but with the help of some suggestions from Russ Croman, had finally gotten something that I thought looked good.  During that extended discussion (across a couple of message threads), Uwe asked if I'd be interested in processing his Sh2-170 data myself to see what I could get out of it.  I accepted and hoped I could find a path to something that Uwe would find acceptable.  This image is that result;  my heartfelt thanks to Uwe for trusting me with his data!!!

This image began from a SHO/ForaxX palette at its foundation.

This nebula is dim (practically invisible outside Ha and O3), so there is some limit as to how much fainter detail can be pushed.  

The challenge with this dataset (and the target) is that only Ha and O3 are really a factor and there is no physical separation of the two emmission sources in the target - they completely overlay each other.  As a result, any of the standard palette applications result in what is effectively a monochrome image in something other than gray.

To test/experiment with my options/best path, I created versions in SHO, HSO, HOO, ForaxX SHO, ForaxX HOO using various PixelMath tools and/or scripts in PixInsight.  Once I had my test palettes/channel combinations created, I applied a dynamic crop to all of them, the RGB stars, and the Ha (as Lum) image so they would retain their registration with each other.  The crop is pretty substantial since I felt the nebula was key and the surrounding faint cloud was never going to be bright enough to matter without damaging the overall image.

I used the RGB channel extraction on each of these trial image/palette sets to assess what the resulting RGB channels looked like relative to each other.  I felt this was a critical step since those channels were my resource pool.  To give me the greatest flexibility, the three channels needed to be relatively close in "strength" - IMO.  The new ForaxX script tool in Pixinsight turned out to provide the 'best' of a balanced level of signal in the RGB channels. 

After making that determination, it was just a process of using progressive range masks to pull / push a specific portion of the palette in specific regions of the nebula to create some differentiation.  Some might have used GAME masks, but I prefer to use a Range Mask in this instance because it follows the natural brightness curves within the nebula as the mask is adjusted.  That prevents (IMO) imposing artificial gradients/transitions.  IMO - YMMV.

A combination of mask application and PI's Curves tool created the image posted here (I also added a modified version of the Ha image as a Lum layer using the LRGB combination tool in PI).

The dim dust/molecular cloud surrounding Sh2-170 can be seen in this image although it is very faint.
Revision B is posted that shows a slightly higher contrast image of the Nebula vs the background - the faint dust is not visible in that revision.

Please follow the link above to Uwe's original posting and subsequent new versions.  It is this sharing of ideas and suggestions that make Astrobin such a great experience and resource for new and experienced astrophotography enthusiasts, in my opinion!!!
Clayton Yendrey

From Wikipedia on Sh2-17):Sh2-170 is an emission nebula in the constellation Cassiopeia.It is located in the northwestern part of the constellation, about 5° north of the star Caph; The most suitable period for its observation in the evening sky falls between the months of August and January and is greatly facilitated for observers placed in the regions of the terrestrial northern hemisphere, where it is circumpolar up to the warm temperate regions.Sh2-170 is an H II region located on the Perseus Arm about 2300 parsecs (about 7500 light-years) away, near the edge of a large superbubble originating from the combined action of the stellar wind of the Cassiopeia OB5stellar association.