TheSkySearchers

This month we have a beautiful nebula which combines both refection and emission nebulae and is given to us by @KathyNS - Thanks Kathy!

I think this month will be a bit more of a challenge for some of us. Kathys own words when she gave us the data were "It is not bad data, but it is not necessarily an easy process". Kathys' original post is here so you can see what we have;

viewtopic.php?f=66&t=18831&p=156796&hil ... 59#p156644

The data came from a 8" Orion imaging newt and an Atik 383L+ and we have Ha, L and individual RGB's - note that the RGB's are binned 2X2, Ha and Lum 1x1. If anyone is unsure about combining channels then just post here telling us what software you are using and I'm sure someone will give you pointers.

For PCC it will solve at 800mm FL and 5.4 micron pixel.

Kathy gave us .XISF files and I've converted to 32b FIT and 16b tiff for those not using Pixinsight. You can find all the files here;

https://1drv.ms/u/s!Alj6NhuYfZtW6kIPvZd ... A?e=CldYIc

You know the drill - Download what files you want and process in your software(s) of choice then post in this thread. The purpose of the APP Challenge is to share techniques so we can all learn and grow in our abilities so please describe your process steps and any special tricks you used to get your result. If you have been finding something difficult to do with this data - tell us and hopefully someone will be able to help.

Please consider submitting some data of your own for future challenges. Just send me PM and I'll take it from there.

Enjoy the challenge.

David

Well for once I'm first at getting the challenge posted.

As you know I'm purely OSC so these multichannel images are a real excursion for me. Thanks @KathyNS its great data but as you indicated, not the easiest to process either. I really struggled to get much colour in the reflection components and I'm not sure why.

In Pixinsight and using the .xisf files ;

Dynamic crop and ABE on all mono files
Deconvolution and EZ denoise on HA and Lum
blended the HA with R in Pixelmath (50:50)
Linear fit, Channel combine and PCC on RGB
HT on HA, Lum and RGB
LHE on HA & LUM Blended Ha and LUM in Pixelmath (70:30 I think) to make HLum (Various masks used but cant remember details )
CT on RGB for contrast and Satuation (slight over-sat)
Convolution on RGB
LRGB combine (HLUM as lum)
Some tweaks in HT/CT for contrast, LUM and SAT
Then into Photoshop for a selective High pass routine and save to jpeg.

All that resulting in;
I had a lot of trial an error in this one and I'm dissapointed I could not get more blue reflection but overall I think its come out OK.

C & C really appreciated - cant wait to see what others do with this.

Take care everyone.

Very nice, @Jockinireland. I like your version better than my own!

new region for me , you did a fine image , thx .

My try at this difficult image.

SPIE7 wrote: ↑Sat Oct 16, 2021 7:13 pm My try at this difficult image.

Not bad! What software did you use and what was your process?

The outer stars look rather green on my screen - any idea how that came about?

Pixinsight with some LR balance. I didnt notice the green until you mentioned it. I have recently started using EZ star reduction and it makes the black empty background look a little strange when you zoom in. But, I like the stars less obtrusive.

Thanks for the data Kathy and thanks for sorting the Challenge David.

Seems I'm just a simple OSC, PI beginner kind of bloke! I couldn't find a way of integrating all five files so I just used the RGBs.

I ran ConvertToRGBColour on the three RGB files and combined them with PixelMaths

Then I ran AutomaticBackgroundExtractor, DynamicCrop, ColourCalibration and BackgroundNeutralisation.

Then used CurvesTransformation to boost the Saturation. Ran SCNR then back in Curves to pull down the blue curve, to reduce the magenta, to increase the red.

There was a TVGDenoise in the mix but I undid it because it went berserk!


I've got the garage capturing pc indoors now with a new monitor and PI installed instead of working with the laptop. So I'll give this another go!

The posted image is not as good as the one on my screen because it's a Snipping Tool capture. I did a save as both .jpg and .png but they didn't work. I think it's because I haven't done a HistogramTransformation.

Regards

Graeme

Hi Graeme,

I don't know what converttorgbcolour is or does

Try this to get to a color image. Open Chanel combination process, put the r, g and b files into the appropriate cell and hit the little square at bottom of the window. (Or maybe the circle - I can never rember) The individual files are well enough balanced that the colours will be ok at that. Then do what you want, gradient removal, ez noise reduction, then use HT to stretch. Boost the saturation a bit with curves transformation.

Then open the lum file, do your gradient and noise reduction then stretch with HT. Once it's non linear, try either hdrmt or LHE to increase contrast.

Then open LRGBcombine, unchecked all the colours leave lum check. Browse to put your lim image in to the right box then drag the little triangle new instamd onto your rgb and you'll have your LRGB image in front of you.

Ah, so you add the Luminance after!

I tried ChannelCombination but it reported "No Compatible Images"!

I'll try it again tomorrow. I have to get up at 05:30 tomorrow to go on a DLR Substation Awareness course. I've only been doing it 40 years! I'm sure their substations are not too dissimilar to ours. Theirs are only 11kV ours are 33kV!

I had another go using the same technique only this time with the HistogramTransformation and the .png file saved ok. Tweaking the curves was fun trying to lift the blues.


The larger stars are blown out but I quite like it!


Regards

Graeme

Kathy ... Thank You for sharing your data on NGC 6559. I really liked your rendition. The subtle transition between the nebula and the dark sky is very aesthetically pleasing. Nice job ... it's a great image!

Here's my take on this nebula. All the processing was done in Photoshop except for a test try of the "deconvolution" technique found in Astroart. It was easy to use and I got good results ... I like it!

I'm not a big fan of using Ha data on a nebula that has a reflection component. The Ha tends to overwhelm the blue data. So, instead of the usual workflow for Ha data, I took the LRGB data and blended the Ha data in as "Luminosity" at 100%. The LRGB data is used as a color layer, only. I'm not sure how well this worked out, since I'm a somewhat color challenged individual. So, any C & C is welcomed ... especially on the star colors.

Additional details on the processing:

- RGB data combined in Photoshop
- Curves
- Levels to set background at 35
- several applications of the above
- noise reduction using the NIK collection for Photoshop.

For the L data
- same as the above
- application of Tone Mapping from the NIK Collection.
- selective noise reduction using the NIK

- RGB and L data combined

For the Ha data ...
- same as the L data
- star reduction Action

- Ha blended in to the LRGB as "Luminosity"

- HaLRGB image:

- selective noise reduction using NIK
- deconvolution using Astroart
- "Selective Color Adjustments" Action to boost overall color

Hi Sky, @Sky

I think thats great. You have got a lot of contrast and structure in the clouds left of centre. As you ask about the star colours, the magenta on some stars and the purple in the bright reflection parts is not really my taste - but the again I totally failed to get ANY colour in those parts so i cant really say much!.

I did a quick invert-SCNR (green removal)-invert to see how it would look (hope you dont mind!). It removes the magenta alright and makes the reflection more blue (which I like) but it tones down the red component a bit too (Which I dont like). That could always be boosted back up in selective colour though.
What do you think?

Jockinireland wrote: ↑Wed Oct 20, 2021 4:16 pm Hi Sky,

I did a quick invert-SCNR (green removal)-invert to see how it would look (hope you dont mind!). It removes the magenta alright and makes the reflection more blue (which I like) but it tones down the red component a bit too (Which I dont like). That could always be boosted back up in selective colour though.

David, just FYI, the link below is to a tutorial that shows how to remove magenta from just the stars without removing it from any of the nebula.

viewtopic.php?f=22&t=11551

Steve

Thanks @STEVE333 that will come in really handy.

Jockinireland wrote: ↑Wed Oct 20, 2021 4:16 pm I did a quick invert-SCNR (green removal)-invert to see how it would look (hope you dont mind!). It removes the magenta alright and makes the reflection more blue (which I like) but it tones down the red component a bit too (Which I dont like). That could always be boosted back up in selective colour though.

What do you think?

Yes .. the stars do look a lot better. Thanks for posting the re-do.

Now, all I have to do is figure out how to duplicate this technique using Photoshop.

Sky wrote: ↑Thu Oct 21, 2021 1:20 pm

Jockinireland wrote: ↑Wed Oct 20, 2021 4:16 pm I did a quick invert-SCNR (green removal)-invert to see how it would look (hope you dont mind!). It removes the magenta alright and makes the reflection more blue (which I like) but it tones down the red component a bit too (Which I dont like). That could always be boosted back up in selective colour though.

What do you think?

Yes .. the stars do look a lot better. Thanks for posting the re-do.

Now, all I have to do is figure out how to duplicate this technique using Photoshop.

If you have the HLVG plug -in for Photoshop then its simply Image-adjustment-invert - run HLVG - image-adjustment-invert - gets pretty close to the same result.same result.

If you dont have HLVG then sorry - I've no idea.

Jockinireland wrote: ↑Thu Oct 21, 2021 2:56 pm

Sky wrote: ↑Thu Oct 21, 2021 1:20 pm

Jockinireland wrote: ↑Wed Oct 20, 2021 4:16 pm I did a quick invert-SCNR (green removal)-invert to see how it would look (hope you dont mind!). It removes the magenta alright and makes the reflection more blue (which I like) but it tones down the red component a bit too (Which I dont like). That could always be boosted back up in selective colour though.

What do you think?

Yes .. the stars do look a lot better. Thanks for posting the re-do.

Now, all I have to do is figure out how to duplicate this technique using Photoshop.

If you have the HLVG plug -in for Photoshop then its simply Image-adjustment-invert - run HLVG - image-adjustment-invert - gets pretty close to the same result.same result.

If you dont have HLVG then sorry - I've no idea.

I gave it a try and it does a pretty good job at taming those off colored stars. This workflow is definitely going into my bag of image processing "tips and tricks".

Thanks for the suggestion ...

I processed this as an Ha HaRGB image. did not manage to get the blues that other people have got though might have another try at it.

Processed in photshop, didn't use the luminance as could not find much data in it, so added Ha to RGB and then added a 2nd layer of ha as a luminance layer. fiddled with colours, and slight use of star reduction.

Carole

I wasn't very happy with my above process too much red top right) so re-did it.

Similar processing except the Ha blend in layers was different.

Aside from the last one, I see enormous gradients introduced that I doubt are real, and that I don't see in Kathy's image.