IC 2944 - HO (+ RGB stars)

[codemonkey]

Pretty happy with how this one came out, starting to feel a bit more comfortable with this NB thing. I'm particularly happy with it given that it was shot under pretty poor seeing conditions.

Andy might be impressed, or at least not disappointed in me because I actually bothered to get RGB stars this time.

Big one here (https://www.astrobin.com/full/hgro9s).

[markas]

This is a spectacular image:thumbsup::thumbsup:


Mark

[codemonkey]

Thanks very much Mark :D

[topheart]

That's just stunning Lee!
I have a strong personal preference for RGB stars in NB images.
Tick!!

Well done!
Cheers,
Tim

[vlazg]

Absolutely awesome Lee, detail is great and the palette is a lot subtler than some we see but still very striking and much more pleasing to my eye.
Well done :thumbsup:

[gregbradley]

Stunning detail. So sharp, amazing.

I see you used 30 seconds for the RGB for the stars and you got nice colour. So perhaps this is a good strategy on regular broadband imaging to get good star colours.

Greg.

[Placidus]

Lee, the RGB stars are astonishingly good.

How, algorithmically, did you get rid of the NB stars? Did you produce a "starless" version and then add the RGB stars?

I'm yet to find an algorithm (such as "use bipolynomial regression on the Winzorised background to interpolate what's under the stars, starting at 0.73 FWHM from centre of star, with a 1.5 FWHM feather", as opposed to "use Bloggs's Photoshop Action" , or "Use Smythe's Pixinsight Process", that does it at all well.

Will understand if it is a secret.

Best,
Mike

[Geoff45]

That's one of the best pictures I've seen for quite a while. It has an ethereal dream-like quality. Nice varied colours and nicely muted.

[codemonkey]

Thanks very much Tim :) I like the nice small NB stars so I always resisted doing RGB stars, but now I've figured out how to get the best of both worlds so now I'm more likely to use them.



Thanks very much George :-) Yeah, this palette is very close to my first attempt at this image, which I think was either the first, or one of the first SHO images I ever did, so I guess that makes it a bit boring compared to some, but I like it.



Thanks very much Greg :-)

I might have gone longer on the RGB stars but for two things: I couldn't be bothered setting up per-event gain, so I shot these at the relatively high gain I use for NB and secondly, my dark library goes from 30s to 180s. Even at 30s with gain 111 I blew out quite a lot of stars.

I get lots of colour in my stars (often too much) by using Arcsinh in PixInsight to do the majority of the stretch.



haha, thanks Mike :-)

No real magic here on my part, I'm standing on the shoulders of giants. I used Starnet++ to remove the stars... I used the PixInsight plugin version, but you can also get a CLI version of it if you're inclined..

Starnet++ uses AI to remove the stars. Unfortunately the model was trained using a refractor (a Tak I believe?) so my stars don't fit the model all that well. It does a pretty amazing job even still, but leaves quite a lot of artifacts that I have to clean up... I did that using clone stamp.

From here I applied my one "trick" which I thought of recently. Pretty obvious in retrospect, I'm sure others have been doing this for ages and I'm just late to the party. Sounds more involved than it is, but...

* I extracted the starless H from the star-filled H; this leaves me with an image containing just the H stars
* I stretched the RGB colour image containing the stars to roughly approximate the size of the H stars (very roughly, not really important)
* I separated the RGB stars into channels a and b from the lab colour space
* I separated the fully processed starless NB image into L, a and b channels
* Using the H stars as a mask, I blend the a and b channels from the stars into the a and b channels from the NB image
* I then add the H stars to the L channel from the NB image
* I now recombine the Lab channels and have a NB image with stars the size of the H ones, but the colour of the RGB ones

Hope that makes sense (and helps!)



Wow Geoff, thanks for that, I really appreciate the kind words :D

[multiweb]

Very cool Lee. Poolroom material. :thumbsup::thumbsup::thumbsup:

[codemonkey]

Thanks again Marc :D

[Atmos]

Very nice Lee!

Your method of adding small RGB stars isn’t one I’ve tried before but one I’ve considered doing when I get back into mono imaging so it’s good to have it confirmed as a viable option :thumbsup:

A very good rendition of a dynamic object!

[Andy01]

Yep, great image - well done! :thumbsup:
Just my 2c worth but pink stars are darn ugly and white ones are boring! :lol:



Very interesting technique Lee - I'll have to try that one out myself! :thanx:

[Retrograde]

Very nice Lee!

Narrow-band images with RGB stars seem like the best of both worlds to me (despite the fact that I realise there's a huge amount of work being done in the background). Great result.

Cheers,
Pete

[multiweb]

So what are you going to put on the DEC of that monster mount you got? An observing chair? ;)

[CalvinKlein]

Lovely result Lee - and I've just put 2 & 2 together and linked your IIS and Facebook names :)

[codemonkey]

Thanks Colin :D Yeah, I think it's going to be my go-to method going forward, I like how it turned out. If only Starnet++ resulted in less artifacts... still pretty tedious trying to clean that up.



Fully agree that the pink ones are hideous. White ones don't bother me so much. There's another option though and that's to use the same NB data to try and simulate RGB colour... I did that in this image (https://www.astrobin.com/full/d7oal9/D/) and I think that can work pretty well too.




No probs mate, hope it's useful



Thanks very much Pete :D



haha. A distinct possibility. Amusingly I don't even know what I'm going to put on it. I didn't even intend to buy that mount... I woke up, started talking to my wife about something totally unrelated... I somehow turned the conversation to the Mesu I'd seen advertised and by the end of the conversation we'd agreed that I would buy the mount. I think I have a problem.

My vague plan was to eventually get something 12"+ but I knew I'd need a bigger mount for that and had made no real plans to get one for financial reasons. I'll probably build/buy a 12-16" newt.



Thanks Kelvin! :) You're not stalking me, are you? :rundog:

[multiweb]

nah... get a 25" obsession dobs and bolt it on top. :lol:

[codemonkey]

:lol: I was having a look around last night at various commercially available scopes in the 12"+ range and what I'd never really considered was how I'd actually go about getting one onto my mount. I have no intention of buying one, but the 16" GSO Truss RC are 37kg for example.

As I said, this wasn't really a plan other than I had a vague idea that I'd like something bigger eventually... now I think I'm gonna have to bulk up to be able to deal with such a scope :lol:

[Slawomir]

Great image Lee, awesome detail and colours - you have presented this popular target in a completely new light :thumbsup::thumbsup::thumbsup:

[Ryderscope]

Well done Lee and thanks for the discourse on adding RGB stars.

[LewisM]

That image has some lovely depth and 3D feel Lee. Love it.

[strongmanmike]

Awesome!

Mike

[codemonkey]

Thanks very much Suavi, glad you like it :D



No probs Rodney, hope people find it useful!



Thanks Lewis! Good to see you back buying up Tak's again ;-)



Thanks Mike! And for your comments on all my other images too... I'll just say thanks here for all of them so I don't bump up images I'm sure people are sick of looking at already :lol:

I actually had a 20x30" canvas printed of this one which just arrived yesterday. I've never really been happy with any of my astro prints but this one turned out exactly as I expected. Very happy with it. Makes me want to get some more!

[strongmanmike]

:lol:...clearly I have a man crush on your images :face: :lol:

Bet it looks amazing...please post a shot of it...or at least send me a look see :prey:

Previously Banished Mike :D

[codemonkey]

Finally got some hooks so the print went up today. Looks bigger in the flesh. Colour/contrast looks different in the photo but it turned out pretty close to what I see on my screen... fractionally less green/orange and more blue/yellow but that's what I expected.

[Nikolas]

That is gobsmackingly astounding!

[strongmanmike]

Looks awesome Lee :)

[Paul Haese]

That is very nice Lee. I like the detail the most. Nice smokey look to the image too.

[codemonkey]

Thanks Nik :D



Thanks Mike :) It's definitely my favourite print to date.



Thanks very much Paul, glad you like it :)