Vdb-141 (Ghost Nebula) LRGB

[Rodd]

18 minutes ago, Barry-Wilson said:

I did miss your Cocoon and am looking now on AstroBin: it is an excellent image and a very good example of sympathetic processing with the result that the image doesn't look like it's been processed.

The Lum stack is stretched maybe a shade too far for my taste. One indication are the stars and another the loss of definition and contrast around the outer limits of the Ghost itself.  I use pixel values as a guide but do not use them as a 'target' nor as a 'limit'. Rather when I stretch an image my process is a strange amalgam of technical reference and . . . feel. If the stacked channel demands less of a stretch than the numbers would indicate, I stretch it a little less. If the channel needs more than an ideal pixel reading, I'll stretch it more.

I have used PixInsight's new colour calibration PCC tool a couple of times now, selecting a preview of a background too. I have found after using this in conjunction with the new Local Normalisation routine, that I have not needed to use DBE. I would never use ABE on an image; it is just too coarse in my experience.

The data is very good so I encourage you to give it another go.

HTH

Barry

Barry--I may have found part of the problem.  In the LRGB combination tool I had the saturation set at about .42 (.5 is in the middle and as you go down saturation goes up as you know).  That added chroma so it could not have helped.  Here is a quick attempt using the LRGB combination tool with the light and chroma set in the middle.  Looks like there are fewer chromatic gradients.  I did not need as much noise control as a result.  Better?  Olly may think the neholosity looks "clayish", and I probably concur, but I guess I can't have everything.  If I am right about it having fewer gradient, this will be a decent starting point.  I think the bacvkgroiund is better--but there might be some gradients in the nebula itself.  Hard to say--I have been looking at it too long!

[Rodd]

Here is why I think it looks like an Octopus instead of a Ghost

 

[Rodd]

So...to wrap up a long and twisted road, I have managed to improve the image I believe.  At least the background gradients are gone, and the smearing of the noise control is at a minimum . I used the new photometric color calibration tool--maybe that helped.  I was also more careful with my stretches. But the faint nebulosity is still  grainy.  Better?  I think so.. but still not what one would expect from 22 hours of exposure using a quality instrument.  For reference, I have included a splendid example of this target--its from Wikipedia.  Yes it was taken with a much lager instrument, but note how the background nebulosity is airy, thin, gaseous.  Space looks vacuous.  Mine is like clay.  Definitely not like super thin clouds of ionized hydrogen.  The ghost (or octopus) itself is passable.  But I am left wanting.  Maybe I  I should stick to narrow band. 

Mine

 

The real deal