Baby steps around the Crescent

[JamesF]

Feels like it's been miserable weather since forever, so I've finally got things organised to do a bit of processing.  Well, organised to do a bit of learning about processing really.  When Photoshop-wrangling is required, I am only an egg.

So, this is a first pass at processing my data from the Crescent.  Something of a motley collection of files, with five hours of Ha, four hours 45 mins of OIII, three hours of luminance, one hour 45 minutes of each of red and green and an hour of blue, all as fifteen minute subs, using my Atik 314L+ and 80ED.  There was more blue, but it was awful so I threw it away, and in the end I didn't use the luminance data (which is what I captured first).  So, this is actually HaR for the red channel, OIIIG for the green and straight blue, reusing the HaR as luminance, totalling fourteen hours and 15 minutes integration time, scaled to 50%.

I'm not exactly unhappy with it, but not entirely happy either.

There's no sharpening and I think I need to get my head around that.  I did try some deconvolution, but I wasn't happy with the results.  I'm wondering if I should perhaps have combined the OIII data with the blue channel as well as the green.  I think there's more there than really shows up and perhaps that would make it stand out a little better.  At the moment I think the green shell looks like an artefact when I'm pretty sure it's genuine data.

It would be nice to have the stars a little better controlled, too.  Sharpening might help with that, I guess, but it's something else to work on.

James

[carastro]

Considering there was no Luminance that's come out pretty well.  You can always use the ha for a 2nd time as the luminance channel, it should hopefully sharpen it up a bit.  I#d also try as you suggested combining the Oiii with the blue channel.

I must admit if I had processed this I'd have done HOO with RGB just for the stars. 

Carole 

[Laurin Dave]

That’s good, and there’s nice detail in the Ha..  i’d do as you and Carole suggest and blend the Oiii into the blue channel as well using blend mode lighten ..  also I’d do this at 100% opacity and reduce the Oiii in green to 70% opacity .  This will give the Oiii shell a slightly bluer colour ..  allegedly more natural ..  you could also try combining the Oiii and Ha (again using blend mode lighten Oiii over the Ha) to use as a luminance layer..  then apply in stages using the opacity slider 

Dave

Edited December 15, 2019 by Laurin Dave

[lux eterna]

I agree the colours could be tweaked a bit, but besides that I see a very good picture with lots of detail. And not over-processed. I experimented with the jpg (hope you do not mind) :

I was aiming for replacing green with blue, and enhancing the red a little. So I copied the blue channel to a separate layer, and then the same thing with the green channel (on top). Then I changed blending mode of the top layer to "lighten", and produced a third (top) layer by pressing shift-ctrl-alt-e (called "stamp visible"). Copy & paste that "stamp visible" layer into the blue channel of the original image and delete the three temporary layers created as above.

Then I tweaked a bit with adjustment layers "selective colour" and "hue/saturation". Not saying this is better, but different, and in the end it´s up to personal taste.

BTW, what equipment did you use ?

Ragnar

 

[JamesF]

2 hours ago, carastro said:

Considering there was no Luminance that's come out pretty well.  You can always use the ha for a 2nd time as the luminance channel, it should hopefully sharpen it up a bit.  I#d also try as you suggested combining the Oiii with the blue channel.

I must admit if I had processed this I'd have done HOO with RGB just for the stars. 

Carole 

Thank you, Carole.  I'll experiment with using the narrowband data for the nebula and RGB for the stars once I've worked out how to do it

James

[JamesF]

1 hour ago, Laurin Dave said:

That’s good, and there’s nice detail in the Ha..  i’d do as you and Carole suggest and blend the Oiii into the blue channel as well using blend mode lighten ..  also I’d do this at 100% opacity and reduce the Oiii in green to 70% opacity .  This will give the Oiii shell a slightly bluer colour ..  allegedly more natural ..  you could also try combining the Oiii and Ha (again using blend mode lighten Oiii over the Ha) to use as a luminance layer..  then apply in stages using the opacity slider 

Dave

It's definitely looking like using the OIII for the blue channel is favourite

James

[JamesF]

56 minutes ago, lux eterna said:

I agree the colours could be tweaked a bit, but besides that I see a very good picture with lots of detail. And not over-processed. I experimented with the jpg (hope you do not mind) :

I don't mind at all.  I definitely think it looks better with the brighter blue.  I wonder if that's partially because we get used to seeing a green cast as a defect in images...

56 minutes ago, lux eterna said:

BTW, what equipment did you use ?

Skywatcher ED80, Atik 314L+ and Baader filters all on top of an NEQ6.

James

[JamesF]

I've had another crack at this and I think it's better in some respects, but I'm coming to the conclusion that I really have to get rid of the stars and process them and the nebulosity separately as trying to pull more out of the OIII to bring up the green/blue of the nebula just messes up the star colour.

Actually, I think I probably need to remove the stars and then mask off the nebula itself so I can just work on that and pull up the colour without messing up the surrounding Ha, but my Photoshop skills don't extend that far yet...

James

[Rusted]

?

Edited December 16, 2019 by Rusted

[JamesF]

The contrast looks much better in those and for me it confirms that the one I posted second is actually a better rendition of the data other than the star colours.

What did you do to change them?

James

[Rusted]

22 minutes ago, JamesF said:

The contrast looks much better in those and for me it confirms that the one I posted second is actually a better rendition of the data other than the star colours.

What did you do to change them?

James

Just a couple of clicks of contrast and a minus click of gamma.
One has an extra dollop of colour saturation to bring out the green.
All the work of free PhotoFiltre7. I've been using it for years on my landscape photos.
I could never afford Photoshop. Nor spare the brain cells to learn how to use it.
So I use PF7 on my solar and astro daubs too.

[Adreneline]

15 hours ago, JamesF said:

I've had another crack at this and I think it's better in some respects

Hi James,

I prefer the second version.

Hope you don't mind but I've had a crack at it as well. I did a little bit of noise reduction to try to reduce the coloured star rims and then bit more noise reduction to reduce noise overall in the image. I then had a fiddle with selective colour. I also reduced the star size across the image by a very small amount and tweaked the saturation a very small amount. (All in Photoshop).

As you say it is purely subjective.

Hope you don't mind

Adrian

[JamesF]

Looks very nice, Adrian.  I have no objection to people making changes to the image -- I know that I'm really not that good at driving photoshop and have a lot to learn.  It does make me feel as though fundamentally the data I have isn't at all bad, which is a positive.

James

[Adreneline]

2 hours ago, JamesF said:

It does make me feel as though fundamentally the data I have isn't at all bad, which is a positive.

I am sure the data is very good. Processing is such a challenge and there is no "one rules fits all" either. With data in short supply we have to make the most of what we've got.

I do like subtle colours though so your image works for me.

Adrian

[ollypenrice]

What I would do would be make a moderate RGB stretch, or an LRGB. If the L is proving difficult you don't have to add it at 100%, remember. I'd be looking for nice clean, properly coloured stars in this as the overwhelming priority. I wouldn't chase the nebulosity in this image.

I'd then make an HaRGB out of the above with Ha added to red in blend mode lighten. I'd brutally star reduce the Ha stars because I wouldn't want them in the final image and as long as they are less bright than the red stars they won't be, using 'lighten.'

Next I'd make two more images, the new HaRGB with OIII added fully to green, same technique as above, and another HaRGB with OIII to blue, ditto.

Then I'd make a three layer construction in Layers:

Top       HaRGB ( with OIII to blue)

Middle  HaRGB (with OIII to green)

Bottom  HaRGB

Now you have complete control in real time and don't have to guess how to distribute the OIII between green and blue. You can use the opacity sliders to balance the green-blue components of the OIII while aiming for that teal blue colour which is true of OIII. You can also decide how much of the total OIII you want in the final image.

Personally I would beware of Ha as luminance on this target because it will subdue the distinctive OIII outer shell.

The method I suggest here is, in reality, Carole's HOO with RGB stars but I think the method is more controllable, easier and will potentially allow a little of the colour subtlety of RGB nebulosity into the final image. An L layer might enhance this possibility by lifting some of the RGB nebula colour above the brightness of the added narrowband but one can't be certain.

Olly

PS Edit. When doing this I leave the RGB-only image open so I can use it as a colour reference for the narrowband-enhanced image.

Edited December 18, 2019 by ollypenrice

[JamesF]

Thanks for your comments, Olly.  Much appreciated.  Now I just have to work out what that all means in terms of how to do it in Photoshop   I think perhaps I need to take a few steps back and learn a bit more about how some of the elements of Photoshop work.

Still, what else are christmas holidays for?

James

[Rusted]

I think Olly's speaking the same language as Gina.

Try this:

Google Translate