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Bubble Nebula processing: Siril vs APP differences in IFN representation

Aries Productions Astro Pixel Processor (APP) Siril Team Siril Processing
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Aquawind avatar
Aquawind avatar

I need to get over this basic issue I have processing in Siril vs APP and specifically narrowband processing. If you look at my latest image of the Bubble Nebula you will see the difference. The IFN is so different. I understand this can also be art but, I like to be more true representation well, closer to with my mediocre skills. What am I seeing? Can APP pick up that IFN or is it actually overdone in Siril? Is it good or kinda over stated? Is it IFN? LOL Good thing I can laugh at myself. I do use the scripts for stacking. I appreciate your time.

CS, Paul

Tony Gondola avatar
Tony Gondola avatar

I’m not sure what you’re asking exactly about the processing but I think most if not all of what you are calling IFN is dim Ha emission which is all over that area.

andrea tasselli avatar
andrea tasselli avatar
It seems quite improbable, given the no-filter usage, that you could go this deep in picking up Ha or SII, especially in areas basically devoid of such or much else in fact. IFN is an acronym for Integrated Flux Nebula and refers to scattered light from interstellar dust by the combined light of the galaxy and I can see no sign of it in your image.
Aquawind avatar
Aquawind avatar

Ok, So with my Siril processing it’s picking up alot more dim Ha than my APP in this case. Thanks for clarifying what I am seeing. This would probably be obvious if shooting in mono. I have not separated my channels when processing with my OSC. I like APP and paid for it. I kinda feel like it’s leaving data on the table being I cannot duplicate the data Siril is picking up by default.

Thanks Tony

Aquawind avatar
Aquawind avatar

andrea tasselli · Oct 26, 2025, 06:27 PM

It seems quite improbable, given the no-filter usage, that you could go this deep in picking up Ha or SII, especially in areas basically devoid of such or much else in fact. IFN is an acronym for Integrated Flux Nebula and refers to scattered light from interstellar dust by the combined light of the galaxy and I can see no sign of it in your image.

Thank you! Now I know.

Matthew Singer avatar
Matthew Singer avatar

Your image is quite good, as are the others in your gallery!

At one point, I too was questioning the software I was using, so I processed a lot of my data using just about everything I could try: AstroImageJ, MaxIM DL, Siril, APP, and PixInsight - meaning the same datasets in all of those different apps.

In my case, I found that each app produced different results; none were better or worse, just different. I finally settled on an approach that works well for me.

Bear in mind, too, that there’s no single “true representation” of just about anything, including astronomical images. A lot depends on the meaning we attach to it and on how we relate to it.

There are conventional representations, where many people agree that something appears “as it should”: that’s a broader group opinion. If you want to appeal to that group/opinion specifically, you have your answer about whether your image is congruent with that by comparing your image with popular astronomical images of your subject.

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Aquawind avatar
Aquawind avatar

Matthew Singer · Oct 26, 2025, 06:58 PM

Your image is quite good, as are the others in your gallery!

At one point, I too was questioning the software I was using, so I processed a lot of my data using just about everything I could try: AstroImageJ, MaxIM DL, Siril, APP, and PixInsight - meaning the same datasets in all of those different apps.

In my case, I found that each app produced different results; none were better or worse, just different. I finally settled on an approach that works well for me.

Bear in mind, too, that there’s no single “true representation” of just about anything, including astronomical images. A lot depends on the meaning we attach to it and on how we relate to it.

There are conventional representations, where many people agree that something appears “as it should”: that’s a broader group opinion. If you want to appeal to that group/opinion specifically, you have your answer about whether your image is congruent with that by comparing your image with popular astronomical images of your subject.

Thank you Matthew! I do like both programs. I appreciate your added overview of my uncertainty.

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Habib Sekha avatar
Habib Sekha avatar

Hi Paul/Aquawind, I just looked at the histograms of your renditions. In the first one the green channel looks clipped and the red channel is either stretched too much or has been shifted to the right. It is IMHO very likely a processing thing (independent of the software used).

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andrea tasselli avatar
andrea tasselli avatar
andrea tasselli · Oct 26, 2025, 06:27 PM

It seems quite improbable, given the no-filter usage, that you could go this deep in picking up Ha or SII, especially in areas basically devoid of such or much else in fact. IFN is an acronym for Integrated Flux Nebula and refers to scattered light from interstellar dust by the combined light of the galaxy and I can see no sign of it in your image.

Thank you! Now I know.

You got the stars all wrong, I mean the locations, they are flipped horizontally. And that little yellowish crab-like object... is it a new discovery because I can't find anything like it in stock pictures.

Edit: the little yellow crab is actually GN 23.15.3, a small, dim reflection nebula which shouldn't really looking like it does nor be as prominent. Most of the wide field pics I looked at are in NB so they easily missed this one.
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Aquawind avatar
Aquawind avatar

Habib Sekha · Oct 26, 2025, 07:23 PM

Hi Paul/Aquawind, I just looked at the histograms of your renditions. In the first one the green channel looks clipped and the red channel is either stretched too much or has been shifted to the right. It is IMHO very likely a processing thing (independent of the software used).

That sounds right. Thank you!

Aquawind avatar
Aquawind avatar

andrea tasselli · Oct 26, 2025, 07:28 PM

You got the stars all wrong, I mean the locations, they are flipped horizontally.

Wow you are correct. Somehow the stars got flipped on both or the nebula on the original? Wow I really appreciate you jumping in Andrea! When in Siril I plate solve the image before applying SPCC and it can flip the image. I rarely rotate my images and especially when not already combined. Back to my mediocre processing and understanding. The unsolved crab like feature was just another reason to question what I was seeing.

Thank you!

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Tony Gondola avatar
Tony Gondola avatar

This is something that can really catch you out. I don’t know if the PI guys have this issue but it can certainly happen in the Siril world. If there are bright stars in the frame you can usually catch this problem when you recombine because the diffraction spikes or halos don’t line up but in fields where that are no really bright marker stars, it can be easy to recombine incorrectly. When I first look at a new data set I’ll always do a quick stack and stretch to get an idea of what I have. I always keep that as a reference image just to prevent the flip thing from happening.

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Aquawind avatar
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Tony Gondola · Oct 26, 2025, 08:02 PM

This is something that can really catch you out. I don’t know if the PI guys have this issue but it can certainly happen in the Siril world. If there are bright stars in the frame you can usually catch this problem when you recombine because the diffraction spikes or halos don’t line up but in fields where that are no really bright marker stars, it can be easy to recombine incorrectly. When I first look at a new data set I’ll always do a quick stack and stretch to get an idea of what I have. I always keep that as a reference image just to prevent the flip thing from happening.

Yeah this is part of the problem with using multiple programs and formats as you can get a bit lost going back and forth for multiple renditions. Humbling thread for sure. Sometimes we learn the hard way. Thank you!