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2022-09-02: APP 2.0.0-beta4 has been released !

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windows 2.0.0-beta4

macOS x86_64 2.0.0-beta4

macOS arm64 M1 2.0.0-beta4

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Problems with integrating Ha/OIII to RGB

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(@juergenn)
White Dwarf Customer
Joined: 1 year ago
Posts: 25
Topic starter  

No problem. Its not an critical issue for me (since I have a workaround), but would be nice to know the root cause for this behaviour.


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(@mabula-admin)
Quasar Admin
Joined: 5 years ago
Posts: 3228
 

Hi @juergenn,

I just had a look at your data and tried to combine the R,G,B, Ha, O3 stacks with the RGB Combine tool. The weird result that you get with the drizzled data has to do with normalization of your data in the tool, especially multiplicative normalization does not work well. Simply set the normalize option to add-scale or none, since you already normalized the 5 stacks yourself 😉

This is what the RGBHOO formula shosw with add-scale normalization:

RGBHOO normalize add scale

Which looks fine to me.

I think the normalize in the tool is not working well because of the drizzled data, especially the O3 shows clear drizzle artefacts indicating that you use too small drizzle droplets for the data that you were combining. Drizzle needs a lot of subs and under-sampled data to work nicely.

So I suspect that creating the O3 and Ha stacks using drizzle with larger droplets would work okay as well.

Mabula


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(@mabula-admin)
Quasar Admin
Joined: 5 years ago
Posts: 3228
 

Hi @juergenn,

I have made a nice custom RGBHOO formula for your data 😉

RGBHOO custom normalize add scale

Then you want to fix the gradients afterwards witht the Remove Light Pollution Tool:

RemoveLightPollution 1
RemoveLightPollution 2
RemoveLightPollution 3

And then maybe some HSL selective color, to make red more red and Cyan+Blue more Blue 😉

HSL SelectiveColor

Cheers,

Mabula


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(@juergenn)
White Dwarf Customer
Joined: 1 year ago
Posts: 25
Topic starter  

Hi Mabula,

thank you for your help. It was the first time I used drizzle, so maybe I have to look in more detaile into it.

And these are really my data? It looks really great! 😀 I will have another try on my M16 data and see what I get out of it. At the moment I put the narrow band filter data aside, so put them together with the RGB is a work for the next weeks around full moon 😉

 

One additional question: is it necessary to re-stack and produce new Ha and OIII stacks or is it possible to "re-normalize" the existing stacks? As far as I understood I have to restack due to the drizzle problem, right?

 

Edit: I just saw that there is in the combineRGB tool a possibility to normalize! I didnt realized that until now 🤪 


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