Elephant's trunk nebula- processing suggestions needed

[Moonstruck]

I imaged the elephant's trunk nebula (IC1396), and need some suggestions on how to improve my processing in ST. My processed image is fairly faint and does not stand out compared to the surrounding stars. Any advice on how to make this nebula stand out more, and improve the coloration/brightness? I think it is a fairly dim target, so I'm not sure if I can do much more with it. I set the ROI tightly around the curl of the elephant's trunk- not sure if i should have done that, or isolated the entire trunk with the X and Y ROI sliders instead? I would like to keep the surrounding stars (not mask them). Hopefully I can keep the stars but increase the nebula's prominence. Any suggestions?

This has been my greatest challenge so far- I had a pretty tough time even finding this one, in spite of having clear skies!

Here are links to my raw file, and processed image. I took about 3.5 hrs of 60-sec subs, with a gain of about 120, using Sharpcap Pro. These were all taken un-guided. I took 20 darks, 20 flats and 20 dark flats. I have a Skywatcher Esprit 100 ED refractor, EQ6-R-Pro mount and ZWO asi 294 color camera.

Raw autosave file (DSS):
https://drive.google.com/file/d/18dr8CL ... sp=sharing

My processed image:
https://drive.google.com/file/d/1_eJQx2 ... sp=sharing

Thanks in advance.
John

[fmeireso]

Hmmm.

first of all i don't know this object very well. Also it seems that the full nebulae is out the FOV. But maybe you were concentrating on that part only.
Here is my go on it. Tweaked a bit the colors afterwards in GIMP. Used saturate in Superstructure module in order to get the trunk part red or more reddish.
I stretched it also further. Setting the ROi almost on the entire image. I never did that with any other image.....
Guess it needs also more integration time. The surroundings are a bit faint. I also used superstructure-isolate twice to reduce the very busy starfield.
No idea, what do you think?

Etrunk (Large).jpg (414.48 KiB) Viewed 4117 times

[Moonstruck]

Thanks for processing the image. Yours looks a lot better than mine!! Thanks also for the info on what you did. The nebula in yours is definitely more prominent. Yours has a lot of red in it. I have seen this nebula in a variety of colors from other images people have posted (blue, orange, brown, red and yellow) and I wonder which is most realistic. I know coloration is sometimes an artistic rather than scientific endeavor, but I wish there was some standard that showed the "correct" colors for each nebula. But I wonder if nebulas even show color to the human eye or if that is something that is created by our cameras/processing to make it visible to the human eye... there are a variety of thoughts on this.

To answer your question, yes I intentionally framed the image around the elephant's "trunk" rather than the surrounding nebula. My FOV with my ZWO asi 294 camera and Esprit 100 scope is such that I can't fit the whole thing in, so I had to choose what to show. And regarding integration time- I could only get this 3+ hours due to large trees in my yard. To get longer integration I would have to set up multiple nights and combine images... too much of a hassle for me. My mount is very heavy and a bit of a pain to set up

Thanks again. It will be interesting if others post their images (the colors they get, etc). I appreciate your help!

John

[Mike in Rancho]

Good job Freddy, better than mine I think. You got some good practice on your 7000+Pelican though.

John you pick some challenging targets, that's for sure, especially for broadband. But an impressive amount of red nebula showed up nonetheless.

I ran a fairly routine processing up to color, where I may have added a bit more dark saturation, and pulled back on the bright. That gave me some deeper reds but kept the big blue star from being...too big and blue I guess.

I ran a standard Shrink-Unglow, then one SS-Isolate but at gamma 60, and then because I still had sooo many little red stars everywhere, I got selectively artsy and ran another Shrink after automasking only only red.

Not quite as "natural" as Freddy's I think, and perhaps more looking like it almost came from a duoband filter.

As for realistic, one never knows! Unless they disclosed what they did, of course. Blues and oranges sound like narrowband, perhaps SHO, and there's nothing wrong (or fully art) with that. Narrowband is inherently a false color endeavor (and ST has powerful tools for displaying them) but the colors represent real emissions tied to particular wavelengths, which represent certain molecules. For unfiltered broadband, ST's star sampling is awfully good, but Ivo would be the color expert who could explain "reality" much better. Or, he might just say it's a "can of worms" and leave it at that.

I would think the human eye mostly incapable of capturing color from something as faint and diffuse as nebula. But I'd say the same goes for seeing the nebula at all in the first place. So we stretch stacked images captured by cameras in order to "see" what is actually there, and increase saturation in order to "see" the colors that are actually there. Maybe? But the cameras are just collecting photons, after they pass through colored filters, so they aren't creating the colors out of nothing.

Moonstruck ET ST8 1B.jpg (494.42 KiB) Viewed 4096 times

[fmeireso]

Thanks for processing the image. Yours looks a lot better than mine!! Thanks also for the info on what you did. The nebula in yours is definitely more prominent. Yours has a lot of red in it. I have seen this nebula in a variety of colors from other images people have posted (blue, orange, brown, red and yellow) and I wonder which is most realistic. I know coloration is sometimes an artistic rather than scientific endeavor, but I wish there was some standard that showed the "correct" colors for each nebula. But I wonder if nebulas even show color to the human eye or if that is something that is created by our cameras/processing to make it visible to the human eye... there are a variety of thoughts on this.

To answer your question, yes I intentionally framed the image around the elephant's "trunk" rather than the surrounding nebula. My FOV with my ZWO asi 294 camera and Esprit 100 scope is such that I can't fit the whole thing in, so I had to choose what to show. And regarding integration time- I could only get this 3+ hours due to large trees in my yard. To get longer integration I would have to set up multiple nights and combine images... too much of a hassle for me. My mount is very heavy and a bit of a pain to set up

Thanks again. It will be interesting if others post their images (the colors they get, etc). I appreciate your help!

John

John, i uploaded in dropbox the Startools logfile.
If you wish you can download and see all the things i have done. It contains also the mask codification,but that probably will not help much.
If used the color module twice. The second time with a starmask to color the stars separatly because they were very red/orange. I took that a bit back.

Maybe it will help you

https://www.dropbox.com/s/0d2y4im90ovaw ... k.txt?dl=0

[Moonstruck]

Mike- thanks as always for your detailed review and processing! Question- what did you use for your ROI? I just tightly framed the elephant’s trunk curl but maybe I should expand it to get more of the nebula?

[Moonstruck]

Thanks Freddy for the log file and all the other info. John

[Mike in Rancho]

Mike- thanks as always for your detailed review and processing! Question- what did you use for your ROI? I just tightly framed the elephant’s trunk curl but maybe I should expand it to get more of the nebula?

No ROI!

Here's a mask-redacted log, if of any help...

Code: Select all

-----------------------------------------------------------
StarTools 1.8.527MR2
Wed Jun 29 21:42:45 2022
-----------------------------------------------------------
File loaded [G:\ASTRO\2-ST FOLDER\moonstruck\elephants trunk\Autosave.fits].
Image size is 4144 x 2116
--- 
Type of Data: Linear and was Bayered, but not whitebalanced
--- Auto Develop
Parameter [Ignore Fine Detail <] set to [Off]
Parameter [Outside RoI Influence] set to [15 %]
Parameter [RoI X1] set to [0 pixels]
Parameter [RoI Y1] set to [0 pixels]
Parameter [RoI X2] set to [4144 pixels (-0)]
Parameter [RoI Y2] set to [2116 pixels (-0)]
Parameter [Detector Gamma] set to [1.00]
Parameter [Shadow Linearity] set to [50 %]
--- Crop
Parameter [X1] set to [41 pixels]
Parameter [Y1] set to [21 pixels]
Parameter [X2] set to [4103 pixels (-41)]
Parameter [Y2] set to [2095 pixels (-21)]
Image size is 4062 x 2074
--- Bin
Parameter [Scale] set to [scale 50.00% / +2.00 bits / +1.00x SNR improvement]
Image size is 2031 x 1037
--- Wipe
Parameter [Synthetic Dark/Bias] set to [Off]
Parameter [Gradient Edge Behavior] set to [Absorb 50%]
Parameter [Synthetic Flats] set to [Off]
Parameter [Sampling Precision] set to [256 x 256 pixels]
Parameter [Dark Anomaly Filter] set to [2 pixels]
Parameter [Gradient Falloff] set to [0 %]
Parameter [Synth. Bias Edge Area] set to [100 %]
Parameter [Gradient Aggressiveness] set to [85 %]
Parameter [Correlation Filtering] set to [Off]
Redoing stretch of linear data
--- Auto Develop
Parameter [Ignore Fine Detail <] set to [Off]
Parameter [Outside RoI Influence] set to [15 %]
Parameter [RoI X1] set to [0 pixels]
Parameter [RoI Y1] set to [0 pixels]
Parameter [RoI X2] set to [2031 pixels (-0)]
Parameter [RoI Y2] set to [1037 pixels (-0)]
Parameter [Detector Gamma] set to [1.00]
Parameter [Shadow Linearity] set to [50 %]
--- Contrast
Parameter [Expose Dark Areas] set to [Yes]
Parameter [Brightness Retention] set to [Off]
Parameter [Precision] set to [256 x 256 pixels]
Parameter [Shadow Detail Size] set to [10 pixels]
Parameter [Locality] set to [50 %]
Parameter [Shadow Dyn Range Alloc] set to [50 %]
--- HDR
Parameter [Signal Flow] set to [Tracked]
Parameter [Quality] set to [Low]
Parameter [Gamma Shadow (Lift)] set to [1.00]
Parameter [Gamma Highlight (Tame)] set to [1.25]
Parameter [Gamma Smoothen] set to [20.0 pixels]
Parameter [Context Size] set to [50x50 pixels (2.46% image W, 4.82% image H)]
Parameter [Shadows Detail Boost] set to [30 %]
Parameter [Highlights Detail Boost] set to [30 %]
Mask used (BASE64 PNG encoded)
PSF samples used (10 PSF sample locations, BASE64 encoded)
VFMAAAoA7wcNBJsGhwPxAvADCAAqAwgHywIuBvwBnwTpAWQDcALgAYYBDwQ1AfcFSAE=
--- Spatially Variant PSF Deconvolution
Parameter [PSF Resampling] set to [Intra-Iteration + Centroid Tracking Linear]
Parameter [Synthetic PSF Model] set to [Circle of Confusion (Optics Only)]
Parameter [Sampled PSF Area] set to [15x15]
Parameter [Synthetic PSF Radius] set to [1.5 pixels]
Parameter [Synthetic Iterations] set to [Off]
Parameter [Spatial Error] set to [1.00]
Parameter [Deringing Fuzz] set to [25.0 pixels]
Parameter [Deringing Detect] set to [75 %]
Parameter [Dyn. Range Extension] set to [1.00]
Parameter [Linearity Cutoff] set to [85 %]
Parameter [Sampled Iterations] set to [10x]
Parameter [Deringing Amount] set to [0.90]
Mask used (BASE64 PNG encoded)
--- Color
Parameter [Bias Slider Mode] set to [Sliders Reduce Color Bias]
Parameter [Style] set to [Scientific (Color Constancy)]
Parameter [LRGB Method Emulation] set to [Straight CIELab Luminance Retention]
Parameter [Matrix] set to [Identity (OFF)]
Parameter [Dark Saturation] set to [7.5]
Parameter [Bright Saturation] set to [3.5]
Parameter [Saturation Amount] set to [200 %]
Parameter [Blue Bias Reduce] set to [1.00]
Parameter [Green Bias Reduce] set to [1.53]
Parameter [Red Bias Reduce] set to [1.25]
Parameter [Mask Fuzz] set to [1.0 pixels]
Parameter [Cap Green] set to [100 %]
Parameter [Highlight Repair] set to [5 pixels]
Mask used (BASE64 PNG encoded)
--- Shrink
Parameter [Mode] set to [Tighten]
Parameter [Halo Extend] set to [1 pixels]
Parameter [Iterations] set to [5]
Parameter [Regularization] set to [0.85]
Parameter [Color Taming] set to [2 pixels]
Parameter [De-ringing] set to [1.5 pixels]
Parameter [Un-glow Strength] set to [35 %]
Parameter [Un-glow Kernel] set to [30.0 pixels]
--- Super Structure
Parameter [Detail Preservation] set to [Linear Brightness Mask]
Parameter [Compositing Algorithm] set to [Multiply, Gamma Correct]
Parameter [Brightness, Color] set to [Only Brightness]
Parameter [Brightness Retention] set to [Off]
Parameter [Mask Fuzz] set to [1.0 pixels]
Parameter [Airy Disk Radius] set to [60 %]
Parameter [Gamma] set to [0.60]
Parameter [Detail Preservation Radius] set to [20.0 pixels]
Parameter [Saturation] set to [100 %]
Parameter [Strength] set to [100 %]
Mask used (BASE64 PNG encoded)
--- Shrink
Parameter [Mode] set to [Tighten]
Parameter [Halo Extend] set to [1 pixels]
Parameter [Iterations] set to [10]
Parameter [Regularization] set to [0.85]
Parameter [Color Taming] set to [2 pixels]
Parameter [De-ringing] set to [1.5 pixels]
Parameter [Un-glow Strength] set to [Off]
Parameter [Un-glow Kernel] set to [Off]
--- Unified De-Noise
Parameter [Grain Size] set to [3.0 pixels]
Parameter [Walking Noise Size] set to [1.0 pixels]
Parameter [Walking Noise Angle] set to [0]
--- Unified De-Noise
Parameter [Scale 1] set to [99 %]
Parameter [Scale 2] set to [95 %]
Parameter [Scale 3] set to [95 %]
Parameter [Scale 4] set to [95 %]
Parameter [Scale 5] set to [50 %]
Parameter [Equalized Grain] set to [0 %]
Parameter [Scale Correlation] set to [25 %]
Parameter [Color Detail Loss] set to [50 %]
Parameter [Brightness Detail Loss] set to [50 %]
Parameter [Grain Dispersion] set to [6.0 pixels]
File saved [G:\ASTRO\2-ST FOLDER\moonstruck\elephants trunk\Moonstruck ET ST8 1B.tiff].