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Old 13-07-2022, 02:05 PM
Stephane
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The Cat's Paw NGC6334

Hi all,

I have attempted to process this image again, this time trying to draw out the oxygen in the "paws". I am not very experienced when it comes to processing colours and up until this point have rarely attempted to do so.

Advice would be most welcome. Hope you all enjoy. Bigger version here.

Stéphane
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Old 14-07-2022, 11:06 AM
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PKay (Peter)
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Hi Stephane

What you have done is pretty good.

It might help if you offered more info. ie: processing steps used

Also it pays to have a good look at tutorials on youtube.

Take heaps of notes and 'save off' each step so you can backtrack if needed.

I use the mantra after each step in processing: 'better of worse'.

Keep going
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Old 14-07-2022, 11:19 AM
Startrek (Martin)
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Stephane,

That’s a nice Cats Paw ( don’t why it’s called that ) colour look fine to me plus some good detail exposed as well
Stars look tight too
Obviously with the 2600MC with the L Extreme has its limitations when it comes to narrowband imaging but you have done really well exposing some Oiii. Some objects work better than others, this one is difficult
I’m sure in time OSC NB filters will improve further and processing techniques as well

Sorry can’t help you with processing techniques and settings etc… I don’t use PI

Well done !!

Martin
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Old 14-07-2022, 11:49 AM
Dave882 (David)
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That’s beautiful!! Well done!
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Old 14-07-2022, 03:26 PM
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Thanks for your comments Peter, Martin, and Dave.

Peter, here are the processes I used in Pixinsight:
- Dynamic crop
- DBE
- Deconvolution (Followed procedure from VisibleDark on YouTube)
- Stretch
- LocalHistEq applied twice at 64 & 256 with a stretched luminance mask at about 0.35ish amount.
- Starnet2
- Worked on stars a little (morphology, saturation, SCNR, invert+SCNR for magenta reduction)
- Next, I split the channels, combined B and G, stretched it to roughly match the red channel and renamed B. Next I combined 0.6*R+0.4*B for my green channel. I combined all these in LRGBcombination with R as my luminance.
- Worked on colour curves in the nebula. Bumped up the blue mid-tones overall, then used a yellow mask to work on the “orange” hydrogen, and a blue mask to work on the oxygen. Also tweaked other curves: RGB, luminance, saturation,…
- ColorCalibration. Then tweaked colours again a little.
- Combined stars with nebula
- NoiseXterminator at default settings
- Sharpened: Unsharp on a luminance clone, MLT on another luminance clone, then created a new luminance: 15% Unsharp + 15% MLT + 70% lum clone. Then used this as L in LRGB combination.

That’s pretty much it I think. I’d be very curious to receive an analysis on the processes I’m using, their order, and processes I am not using which could have benefited this image.
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Old 14-07-2022, 04:39 PM
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Nikolas (Nik)
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A little more saturation and that would be a stunner
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Old 14-07-2022, 04:47 PM
Stephane
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Quote:
Originally Posted by Nikolas View Post
A little more saturation and that would be a stunner
Nik, I was thinking intensely about increasing saturation a little, but was worried about overdoing it. I should have gone with my gut feeling!
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Old 14-07-2022, 10:33 PM
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PKay (Peter)
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Hi Stephane

As a general rule, I will always do a 'simple' process to use as a reference.
Any fancy processing after that either makes it better...or worse.

In order:

Crop out stacking artefacts.
Background extraction: ABE or DBE
Noise reduction: EZ Denoise Script (default settings). It is important to get rid of noise in the linear stage.
Stretch:
Apply Screen Transfer Function (SCF) using the default settings.
Open Histogram Transformation (HT) and select your image.
Drag the SCF triangle to the bottom of HT.

Apply HT (square button) and then reset it (bottom right).
Reset and close SCF, it has done it's job.
Your image is now non linear.

In HT look at the graph and zoom in. Move the curve to the left until clipping starts. A small amount of clipping is fine (maybe up to a few 1000 pixels).
Apply HT (square button) and reset.
Zoom the image (so you can see the noise)and work on the right side of the HT graph (pulling it down).
Pull the graph down a TINY amount and then apply (square button).
Do this until the noise is reduced (don't over do it).
Save it off.

Curves: I always give a hint of saturation.

That's it, that is your reference image.
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Old 14-07-2022, 10:36 PM
Stephane
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Thanks for the good advice Peter and for taking the time to write that. Much appreciated!
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Old 30-07-2022, 03:23 PM
Addos (Adam)
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real nice details and contrast there! and some very nice gradation between the colour channels!

i agree, give that saturation a little smash and you've got gold. having recently 'rediscovered' it myself, can also recommend a little touch of the 'c' ("vibrance") curve in conjunction with the saturation
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