3 images in progress

[Carles]

I tried processing the extracted Ha / Oiii as separate mono images then Compose - and I don't think it looked much, if any, different from the basic bicolor version I posted above. [oh wait - I didn't use Ha as L, just syn-L, will try again tomorrow]

As long as I had the separated channels, I used pixelmath in Siril the GHS, and wound up with:
Crescent_Siril_HOO_v1-nr_1600_700k.jpg

I *really* don't know what I am doing with GHS, but the Soap Bubble is distinctly visible with what I think is an appropriate "barely there" quality.

Anyway, as to ST - I would like to try opening the ST result in some equivalent of Lightroom to what Carles did with his Lion (is there an open-source equivalent? - can gimp approximate what you did in Lightroom?

Looks good !!
About lightroom, did very basic stuff that surely Gimp can do, i just not used to Gimp, but it is more complete i think than lightroom.

Would you mind sharing the stack so i can test it then share the workflow here if you like.
Could you show also both channels stretched?

Regards
Carles

[dx_ron]

Thanks! The Siril version is my favorite so far. Not just because I prefer the softer, deeper reds, but also because it shows much more fine detail in the Oiii shell than I have been able to recover in ST yet. I think I can see how to get rgb stars in with Siril, though I'd also need to somehow recreate whatever random nudging I did with GHS

Here are stacks

Original: https://www.dropbox.com/scl/fi/ruk7a2jf ... kis46&dl=0

Ha: https://www.dropbox.com/scl/fi/wogr6lhj ... 9r79j&dl=0

Oiii: https://www.dropbox.com/scl/fi/o1nr0lfw ... l821e&dl=0

[Carles]

Hi Ron,

Thank you for sharing your stack. How did you split Oiii and Halpha? Siril or Startools compose method?
Either way, i'm having it very difficult to make the soap nebula to stand out...even with 18h. Do you have many LED in your area?
The Oiii signal is sort of week and noisy. I have processed a friend's image with same sensor as yours (omegon version ) and L-extreme, I would have thought ALPT would be better at isolating Oiii so it is a bit confusing. I'll give it another go and try different stacking but so far didn't have a good result with it :/

Regards,

[dx_ron]

The channels were split in Siril. My backyard runs about 18.7 mag/arc-sec^2, so a challenging environment.

[Mike in Rancho]

The channels were split in Siril. My backyard runs about 18.7 mag/arc-sec^2, so a challenging environment.

Hi Ron, I was playing with those files last night myself. As I told Stefan, SVD really pops the Crescent detail on both mono extracts.

Do you know if the Siril OIII extract takes advantage of the 2xG weighting (about 1.4x IIRC) the way ST does?

[dx_ron]

I assume Siril is just a straight 1:1 channel extract (1+1, I guess?)

I played with a couple of hybrid approaches.

Mostly full HOO in ST, but loaded into Siril before setting colors:

Crescent_ST-stretch_Siril-colors-HOO.jpg (720.86 KiB) Viewed 16172 times

Didn't spend too much time on it in Siril - but it is interesting that it comes out with very ST-like colors. So maybe it is the ST stretching itself that gives the pink/salmon Ha rather than something in ST's color mapping.

Then I Restored the ST version to Linear/Wiped/Deconvolved and moved to Siril for (re-)stretching:

Crescent_SiT-linear_Siril-GHS_v1_1600_700k.jpg (730.88 KiB) Viewed 16172 times

Of course, me just mashing buttons in GHS doesn't help matters

[Mike in Rancho]

Your GHS versions really make the Crescent pop out. Looks cool. But, too much? I wonder if something similar could be done with ROI and/or IFD settings, with the softer nebula clouds but sharper Crescent. Or is that too artistic?

Also in both GHS - where are all the stars?

I like the more burgundy coloring of the prior GHS rendition, as that's something that seems difficult to achieve in an ST HOO. I didn't try optional matrix mapping (a la Martin) but when I have most of them seem fairly close to either HOO or H(H+O)O. Also have to be careful blending separate red and blue to avoid too much purple.

Closest I was able to get was this. I guess under the hood it's still pink and cyan, but with a little more red laced through it.

dxr Cr sep proc HOO ST9 2A 1280.jpg (686.82 KiB) Viewed 16141 times

That's separate mono processing of the Ha and OIII, then recomposed (But had to use RGB, RGB to get color out of in as non-linear. Not sure why, that seems to preclude doing some things). I could get similar but not identical results in a normal ST HOO workflow but fiddling with the three sat controls.

The big improvement was maybe that processed separately I could use NB preset in Wipe for the Ha, but 90% gradient for the OIII. Otherwise the OIII was making some blue fog for me.

But, the one larger star seemed to get stuck trying to decide if it was blue or red. Oops, that's not good.

[Carles]

Your GHS versions really make the Crescent pop out. Looks cool. But, too much? I wonder if something similar could be done with ROI and/or IFD settings, with the softer nebula clouds but sharper Crescent. Or is that too artistic?

Also in both GHS - where are all the stars?

I like the more burgundy coloring of the prior GHS rendition, as that's something that seems difficult to achieve in an ST HOO. I didn't try optional matrix mapping (a la Martin) but when I have most of them seem fairly close to either HOO or H(H+O)O. Also have to be careful blending separate red and blue to avoid too much purple.

Closest I was able to get was this. I guess under the hood it's still pink and cyan, but with a little more red laced through it.


dxr Cr sep proc HOO ST9 2A 1280.jpg


That's separate mono processing of the Ha and OIII, then recomposed (Gut had to use RGB, RGB to get color out of in as non-linear. Not sure why, that seems to preclude doing some things). I could get similar but not identical results in a normal ST HOO workflow but fiddling with the three sat controls.

The big improvement was maybe that processed separately I could use NB preset in Wipe for the Ha, but 90% gradient for the OIII. Otherwise the OIII was making some blue fog for me.

But, the one larger star seemed to get stuck trying to decide if it was blue or red. Oops, that's not good.

Umm yeah, I don't know why this works like it does, as in theory ST process "at the same time, but separately " , but for my Lion Neb Found it very hard to get those results with "normal" workflow or any other workflow that didn't involve processing it first then composing.

The issue I'm having with this is making a Mosaic, Oiii for some reason shows the seams a lot, but can't see much on Halpha (stitching in ASTAP, in raw then process in ST )

[Mike in Rancho]

Umm yeah, I don't know why this works like it does, as in theory ST process "at the same time, but separately " , but for my Lion Neb Found it very hard to get those results with "normal" workflow or any other workflow that didn't involve processing it first then composing.

The issue I'm having with this is making a Mosaic, Oiii for some reason shows the seams a lot, but can't see much on Halpha (stitching in ASTAP, in raw then process in ST )

One thing I have done a few times is to run my separate Wipes (either without an OptiDev, if I've already scoped out the situation beforehand, or if I use OptiDev I will revert to linear but Wiped) and save. Although only 16-bit tiff now, I can compose those.

You are right about mosaics, but from what I've seen all programs can have trouble with those. It just depends. Normalization would seem to be needed, and ASTAP has that option, but perhaps not enough or other things change. That also isn't necessarily going to make gradients match up at the seams even if the images are (globally) normalized for brightness.

There are several programs (I forget the names at the moment but could try to look them up) that are apparently very good at stitching post-processed tiles, but of course you have to have a discerning eye to be able to Wipe, OptiDev, and Color balance in a way that will match. And yes I can see that OIII would be the toughest part.

[Carles]

@Mike in Rancho Right, I have tried ICE for post processing images, with OK results. Although as you mention, processing of the different parts of the stitch needs to be stretched or processed more or less equal, and that is sometimes hard to do.

Other issue with Astap stitch is sometimes some dark artifacts it creates that Wipe don't like much, and depending on the dataset, even colour overlaping creates a bit weird stuff.

Not as bad, but when trying mosaic + preprocessed Halpha and Oiii, here comes the trouble, as the seams are very distinct on Oiii, and it makes it look weird.