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RGB Combine tool and pixel math question  

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(@mcbbcn)
Main Sequence Star Customer
Joined: 2 years ago
Posts: 42
July 24, 2019 22:59  

Hi Everyone and @mabula-admin,

I have an Ha image and a OSC image which I will split into 3 channels. I will want to blend the Ha signal with the R,G,B images using the RGB combine tool.

I would like to add:

80% of the Ha signal into the red channel

20%  of Ha signal into the blue channel

20% of the Ha signal into the green channel

How would I accomplish that using the RGB Combine tool?

Also, is there a way to decrease the signal for a specific color channel while blending it with the Ha signal? Example: Decrease Blue signal 5% while I add 20% of Ha signal.

Best,

Miquel

This topic was modified 5 months ago 6 times by mcbbcn
This topic was modified 4 months ago 2 times by Vincent Groenewold - Moderator

WO 80mm & Maksutov 150mm
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(@mcbbcn)
Main Sequence Star Customer
Joined: 2 years ago
Posts: 42
July 25, 2019 01:51  

Here is an screenshot trying to implement the above settings but I don't know if I'm doing it right. You will see my settings on the left and the right. Also notice how the edge of the Ha image is bleaching through. Is this normal given my settings?

https://photos.app.goo.gl/scuxoqpxWhBfecvR6

Best,

Miquel

This post was modified 5 months ago 2 times by mcbbcn

WO 80mm & Maksutov 150mm
QHY8L & QHY9M


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(@vincent-mod)
Quasar Moderator
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Posts: 1040
July 29, 2019 10:27  

That looks like you're doing it right yes. To have that edge there is because the frames don't line up and basically the data is different at these non overlapping places, giving different appearances.


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(@mcbbcn)
Main Sequence Star Customer
Joined: 2 years ago
Posts: 42
July 29, 2019 22:12  

Hi Vincent,

Thanks for the validation.

I used the below Ha integration and Color integration:

 
 
And my friend Neil was able to create from the above 2 images, the following image using Photoshop with the 80/20/20 blending for the channels.
 
Neil's image: ?dl=0
 
As you can see, in Neil's image, there is no edge and there is this beautiful 3D effect.
 
However, using APP (RGB Cobine, HSL,...), I have not been able to get anywhere near the result from Neil. In my processing, you can see the edge, I don't have near the level of saturation that he has, and it's pretty flattish (no 3D effect).
 
I was wondering if you could give it a try using my integrations above and see how close you can get to Neil's processing, and if you could share pointers, or workflow or steps, tips, that would be great, because I would like to be able to do the same level of processing using APP, but you let me know if it's possible.
 
Thanks for your help,
 
Miquel
 

WO 80mm & Maksutov 150mm
QHY8L & QHY9M


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(@vincent-mod)
Quasar Moderator
Joined: 2 years ago
Posts: 1040
July 30, 2019 10:25  

I'd be happy to give that a try, but then I need some of your calibration files and raw data frames. You can upload those to the following address: AstroPixelProcessor upload and login using appuser as name and password. Maybe make a directory first with your name on it.


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(@mcbbcn)
Main Sequence Star Customer
Joined: 2 years ago
Posts: 42
July 30, 2019 23:45  

Hi @vincent-mod

The Ha image and Color image were already calibrated and integrated using APP, so Neil produced the above processed image just with the Ha and Color images that I just attached above.  He did not use the raw frames, but I will be happy to give it a shot and see if I can upload everything in one location for you.

Thanks for giving it a try,

Miquel

This post was modified 5 months ago by mcbbcn

WO 80mm & Maksutov 150mm
QHY8L & QHY9M


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(@mcbbcn)
Main Sequence Star Customer
Joined: 2 years ago
Posts: 42

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(@vincent-mod)
Quasar Moderator
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July 31, 2019 11:49  

Thanks for the data! I will try to get it all downloaded and see if I can get something nice. I do have a busy schedule the coming week so it may be delayed a week unfortunately.


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(@vincent-mod)
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July 31, 2019 13:20  

ps. I think it's better to save the raw frames and not the fits done by SGP, or are these camera's doing fits themselves?


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(@vincent-mod)
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July 31, 2019 15:24  

So, in the end it turned out to be a bit difficult with the fits files, so I went back to the two integrations. This is my attempt at it. As you can see, mine has less blue. The problem with these type of questions is that it all comes down to personal preference. I like mine in the sense it's less harsh so to say and I trust the color calibration tool a bit more above my own taste. So to me, this data has a bit less color but to get that out requires a lot of (in my opinion) destructive stretching. More data (like luminance and shorter RGB exposures to get the star colors in the center of them) would allow you to do that in a nicer way, hence why I tend to not overdo it. But that's my opinion, you may very well still want another look, I however never pushed APP's settings too much so that will either require more experimentation or the use of something like Photoshop. I can see he used quite a bit of, probably, special tools and filters to get the blue around the stars a bit nicer. Maybe nice to know a little bit about his exact procedure?

combine RGB image mod lpc cbg SC St

 

This post was modified 4 months ago 3 times by Vincent Groenewold - Moderator

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(@mcbbcn)
Main Sequence Star Customer
Joined: 2 years ago
Posts: 42
July 31, 2019 20:08  

Hi @vincent-mod,

When I worked with my Canon 40D from Hutech, I get raw format, but when I worked with my temperature regulated CCD's, I get fits format. As far as I know, there is no loss of quality between what you would consider RAW in DSRL and FITS in CCD.

Best,

Miquel

 

WO 80mm & Maksutov 150mm
QHY8L & QHY9M


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(@mcbbcn)
Main Sequence Star Customer
Joined: 2 years ago
Posts: 42
July 31, 2019 20:18  

Hi @vincent-mod,

Thanks for giving my processing a try. I would interested to know how you got rid off the edge I was seeing on my processing.

I now have both of your images (Neil's image with Photoshop and your image with APP) in the same monitor, so there is no monitor calibration issues by having them in 2 different monitors.

You're correct, I see a noticeable lack of blue in processing and the blue stars, instead of having a nice blue halo around them, they seem to have a blue highlight between 4p-6pm.

What I like about your APP processing: I like your RED rendition and I like the fact, that it is less noisy.

What I like about Neil's APP processing: I like the color balance across all the spectrum and I like that he was able to achieve a higher level of contracts between the the more diffuse nebulose details and the most prominent nebulose details, which give his rendition a less flattish and more 3D effect.

As you said, and I totally believe that,  it's a question of taste.

Best,

Miquel

 

WO 80mm & Maksutov 150mm
QHY8L & QHY9M


(@vincent-mod)
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Joined: 2 years ago
Posts: 1040
July 31, 2019 22:13  
Posted by: @mcbbcn

You're correct, I see a noticeable lack of blue in processing and the blue stars, instead of having a nice blue halo around them, they seem to have a blue highlight between 4p-6pm.

Indeed, it seems to be part of your data, but somehow Neil used a post-processing feature that made it nicer all around. Would be nice to know how he did that.

What I like about your APP processing: I like your RED rendition and I like the fact, that it is less noisy.

What I like about Neil's APP processing: I like the color balance across all the spectrum and I like that he was able to achieve a higher level of contracts between the the more diffuse nebulose details and the most prominent nebulose details, which give his rendition a less flattish and more 3D effect.

Yes he definitely has brought out the colors, but again I would be interested to know if this was done using masks and features like that. In those aspects APP is still lacking, so for some special needs it's still nice to be able to use various software packages. This will be addressed though in future versions.

As to not having an edge, in this example I only replaced the red channel with the Ha data, maybe adding that signal to all channels causes an artefact?


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(@mcbbcn)
Main Sequence Star Customer
Joined: 2 years ago
Posts: 42
July 31, 2019 22:24  

Hi @vincent-mod,

I just contacted Neil and sent him the link to our post and if he has time, I asked him to drop by and see if he can share a few thoughts. I cross my fingers that he can do it, as having folks like you and him exchanging thoughts and ideas, it is a great opportunity for me and folks who don't know as much to learn from the experts.

Best,

Miquel

 

WO 80mm & Maksutov 150mm
QHY8L & QHY9M


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(@vincent-mod)
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Posts: 1040
July 31, 2019 22:29  

That would be great, I'm not considering myself an expert though. 🙂 When it comes to deep post-processing I lack a bit of knowledge, I always used PixInsight and got quite far with that, that still has some nice post processing tools I could use on your image to get closer. Just haven't the time at the moment unfortunately.


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(@mcbbcn)
Main Sequence Star Customer
Joined: 2 years ago
Posts: 42
July 31, 2019 22:34  

Hey @vincent-mod,

Well, when I look at my processing and your processing, I feel like you are more than an expert than I am. 🙂

I think Neil also has some pixinsight experience, but I don't remember. Anyway, it will be good if we can get his (and yours) bits of wisdom for people like me who are running behind people like and him with more experience. I appreciate again you giving it a shot, as I know these things take time. 😎 

 

 

WO 80mm & Maksutov 150mm
QHY8L & QHY9M


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(@neilh)
Molecular Cloud Customer
Joined: 4 months ago
Posts: 3
August 1, 2019 00:20  

I signed up for the 30 day trial to both check out the software and reply to the forum 🙂

I can tell you a few things about my processing of Miquel's picture.

1) It was fast. I didn't really spend more than maybe 10 or 15 minutes on it because I was just showing Miquel what was there. Although, generally speaking, I'm a lazy processor and don't tend to spend more than 20-30 minutes (or occasionally an hour tops) on any given image.

2) I did the initial steps in PixInsight:
- the alignment and cropping of the two images
- the initial stretches and noise reduction
- The saturation of the color image

3) I could have done the pixel math in PixInsight, but chose to do it in Photoshop. 80% of the Ha into the red channel, then 20% into the blue and green channels.
- This does leave the image a little on the green side, so I used the HLVG plugin to reduce the green channel a bit.

4) To make both the red and the blue pop a bit more, also in Photoshop, I used a "Selective Color" layer and pulled probably 60% the cyan out of the red and 60% of the yellow out of the blue. That makes the reds and the blues more prominent without actually increasing saturation which will add chromatic distortion and likely saturate colors you don't want saturated.

The process (the Ha blend and Selective Color) is walked through in detail in a presentation I did a few years back at the Oregon Star Party and linked in this journal entry here:
http://www.myastronomyjournal.com/journal.php?id=nheacock&jd=2011-08-31

I hope that helps.

-Neil


(@mcbbcn)
Main Sequence Star Customer
Joined: 2 years ago
Posts: 42
August 1, 2019 00:37  

Hi @neilh

It's nice to see you here and thank you for sharing the detail explanation of your processing. I look forward to hear the thoughts from Vincent and see if he thinks we can do any of these steps with APP.

Best,

Miquel

WO 80mm & Maksutov 150mm
QHY8L & QHY9M


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(@vincent-mod)
Quasar Moderator
Joined: 2 years ago
Posts: 1040
August 1, 2019 11:29  

Very nice of you Neil to drop by! First I'll reprocess this one with the 80-20-20 mix to see if I can get that to work nicely. Thanks again for the info!

10 min later: Ok, so that mixing did the trick in getting the blue better all around. The big star in front did still loose color after color calibration, overall calibration does look good so I'm wondering what to make of that. I did all steps in APP and I think I'm getting a bit closer to Neil's result. It is more noisy, but that simply a fact of life when you want to get that brownish stuff to get out as well, more data is the only remedy for that. Using APP's sharpening I think I got the details out of the nebula a bit better.

If you're happy with this result Miquel (and credits to Neil for the mixing idea) I can tell you the steps I took.
ps. right-click and open in a new tab gives you the full resolution

combine RGB image mod SC SC cbg csc St

 

This post was modified 4 months ago 3 times by Vincent Groenewold - Moderator

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(@mcbbcn)
Main Sequence Star Customer
Joined: 2 years ago
Posts: 42
August 1, 2019 19:51  

Hi @vincent-mod,

Thanks for giving it another shot. It is starting to have less of flattish look and the stars rendered nicer with full halos around them. Also, the blue is starting to pop-out a bit more. Overall, I like it.  Yes, please, share your workflow steps and thanks for your help,

Best,

Miquel

 

This post was modified 4 months ago by mcbbcn

WO 80mm & Maksutov 150mm
QHY8L & QHY9M


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