Sky Backround with L-Extreme Narrowband

[firebrand18]

Hello team,

Looking for advice/direction. I use the L-Enhance and now L-Extreme on emission nebulae with QHY168C OSC cooled from Bortle 8 and love the performance.

Working on Eastern Veil currently and used the Compose process in StarTools v1.8.512 for HOO Bi-Color image.

In Color, for now, left RGB sliders as-is and boosted contrast; attached are HOO Duoband 100R,50G+50B,50G+50B and H(H+O)O Duoband 100R,50R+25G+25B,50G+50B Matrix options.

Question: how do I make the sky background a neutral black as normally seen in images posted without changing the RGB sliders too much and skewing the actual object color (OIII in the Veil's case)? Can easily turn everything Ha red but then lose the bi-color.

If I go into the Filter module afterwards and use 'Reject" I can push back the blue/brown sky hue but also hits the subject color so not optimal.

Can a selective mask be used to mask out the Veil and stars, invert, and have Filter operate only on the sky background? Clunky approach and also not sure it is 'Documentary' which I always adhere to.

As I have many such targets imaged and doing a re-process with the new 1.8.512 Alpha, anxious to understand best practices to achieve a great result.

Suggestions/input welcome.

Cheers,

Nick

[Mike in Rancho]

I have occasionally used Filter Reject before, but really it has to be done carefully and with caution. Sort of a "break glass only in case of emergency" kind of thing. Reject, Heal, and selective desaturation (Color) I pretty much limit to things like uncorrected or overcorrected dust motes. Oh and Wild Pixels.

You can see my West Veil in the gallery a little bit ago, which was with an L'eNhance. We may have different starting points but I can probably put up a log into that thread if interested.

Veil can be tricky. If you want to post up the stack some of us can take a crack at your background sky and see what all techniques everyone comes up with.

But just looking at your images, I think it's going to be several things to get there -- the right Wipe, the right AutoDev, Contrast possibly with stomping down the shadow dynamic range, SS, Denoise, and if still necessary at the end, a post-tracking FilmDev gamma adjustment (reduction).

It's all a balancing act of course, to try to pull out as much nice detail as the data permits, without having a messy (PI-style) outer space.

[firebrand18]

Fully agree with Reject and Heal; getting into a very grey area; love how you snuck in the "WP" again from previous thread

The jpg's I attached were quick default run-throughs in ST without getting into the heavy tweaks as you mention, just to show a baseline.

Yes, would love to see your Veil log process if you can post.

Would appreciate others taking a crack at the Veil and Sadr region images I just captured. First time uploading FITS stack files (189Mb); how do I go about doing so?

[firebrand18]

Re-processed with aggressive Wipe and narrower AutoDev ROI plus other finer tweaks and no "shady" stuff; very different as expected.

Would be very keen if you or others take a crack to see how each person processes; not sure where to post the huge FITS files.

[firebrand18]

You really can learn a ton with this great community forum; Mike, tried your post-tracking Dev Gamma, boosted a bit on the re-processed version and got this; can play endlessly to tweak images and the feedback and tips help alot:

[Mike in Rancho]

Nice.

The big stacks, often FITS files, are typically linked into the forum rather than posted. The upload is done to Google Drive, or Dropbox, or MS OneDrive, stuff like that, and then set up as a public share. Then post the URL here. I use Google Drive when I need or want to provide a stack, or a bunch of big subs, anything of the sort.

Each time I do it, which isn't even once per month generally, I just erase the old stuff and upload the new. Google gives you 15GB free, and I don't come close to that, but still. It'll break the links if anyone goes into an old post and tries to download, but...the post is usually obsolete by then anyway.

[firebrand18]

Makes sense; figured it would be dropbox or Google drive. Been doing lots of testing out with some of your suggestions and getting good results; every time you approach processing an image, old or new, you learn a bit more and get little bit better, and the new 1.8xxx is really making a difference, Can't wait for Ivo's next release; he mentioned a revamped HDR module.

Let me know if you can post one of your logs as would be great to review someone else's process and see how they approach things.

Cheers.

[Mike in Rancho]

Sorry, been fighting my "new" PC tower getting everything the way I want, so processing and internet took a bit of a back burner. Still working on things...

As an early test of how it runs ST1.8GPU though, I ran through my Veil data quickly. Probably too quickly. The log is almost all defaults, so I'm not sure it's even worth posting. That said, I think it might have turned out better than when I did it a month ago and spent more time fiddling with the settings!

Not much to it. This was L'eNhance data, so similar. Composed as bicolor from DSLR. Wipe was just a bump in Dark Anomaly. AutoDev was intentionally no ROI, knowing the background would be overstretched and I would back it off later. I skipped Contrast as I didn't like the way things shifted for this particular image. HDR and Sharp were full defaults, and Deconv was synthetic. I believe I made a couple changes to the deringing parameters, and in mask I expanded the mask around the handful of bright stars (to aid in the deringing).

Color - just entered full mask, no need for star sampling with bicolor. Selected bicolor then the HOO matrix. Adjusted saturation sliders where I wanted, and put highlight repair on 10. Throughout, I was trying different levels of red channel reduce, and then settled on the balance I wanted. SS defaults, Denoise took default grain but upped scale 5 and brought scale correlation way down. For the end, to back off the overstretched sky and produce the darker outer space look that I prefer, I used FilmDev to drop the gamma (can be balanced with a pedestal from skyglow, but I didn't), fairly aggressively in this case. Then I cropped some junk off the top. I think it might look darker and better with a light border around it, but ST's border is a pretty dark gray.

Anyway not bad I guess for a quick test, might be cleaner if I spent more time on it. And the computer didn't crash either!

Code: Select all

-----------------------------------------------------------
StarTools 1.8.512alpha
Fri Sep 24 17:16:47 2021
-----------------------------------------------------------
Loading red channel data
File loaded in LRGB module [D:\PRE-PROCESSING\NGC6960\NGC6960 FS LE 7-28-21\Veil k2-5 9hr and opt dark.fts].
Loading green channel data
File loaded in LRGB module [D:\PRE-PROCESSING\NGC6960\NGC6960 FS LE 7-28-21\Veil k2-5 9hr and opt dark.fts].
Loading blue channel data
File loaded in LRGB module [D:\PRE-PROCESSING\NGC6960\NGC6960 FS LE 7-28-21\Veil k2-5 9hr and opt dark.fts].
--- Compose
Parameter [Luminance, Color] set to [L + Synthetic L From R(2xG)B, R(GB)(GB) (Bi-Color from OSC/DSLR)]
Parameter [Color Ch. Interpolation] set to [On]
Parameter [NB Accents Type] set to [Ha/S-II from NB filter]
Parameter [Lum Total Exposure] set to [Not set]
Parameter [Blue Total Exposure] set to [1h00m (60m) (3600s)]
Parameter [Green Total Exposure] set to [1h00m (60m) (3600s)]
Parameter [Red Total Exposure] set to [1h00m (60m) (3600s)]
Image size is 5882 x 3830
Type of Data: Linear, was not Bayered, or was Bayered + white balanced
--- 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 [5882 pixels (-0)]
Parameter [RoI Y2] set to [3830 pixels (-0)]
Parameter [Detector Gamma] set to [1.00]
Parameter [Shadow Linearity] set to [50 %]
--- Bin
Parameter [Scale] set to [scale 50.00% / +2.00 bits / +1.00x SNR improvement]
Image size is 2941 x 1915
--- Crop
Parameter [X1] set to [15 pixels]
Parameter [Y1] set to [15 pixels]
Parameter [X2] set to [2926 pixels (-15)]
Parameter [Y2] set to [1900 pixels (-15)]
Image size is 2911 x 1885
--- 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 [5 pixels]
Parameter [Gradient Falloff] set to [0 %]
Parameter [Synth. Bias Edge Area] set to [10 %]
Parameter [Gradient Aggressiveness] set to [75 %]
Parameter [Correlation Filtering] set to [Off]
Redoing stretch of linear data
--- Auto Develop
Parameter [Ignore Fine Detail <] set to [3.8 pixels]
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 [2911 pixels (-0)]
Parameter [RoI Y2] set to [1885 pixels (-0)]
Parameter [Detector Gamma] set to [1.00]
Parameter [Shadow Linearity] set to [50 %]
--- HDR
Parameter [Small Detail Precision] set to [Max]
Parameter [Channels] set to [Brightness Only]
Parameter [Algorithm] set to [Reveal All]
Parameter [Dark/Bright Response] set to [1.00]
Parameter [Detail Size Range] set to [1000 pixels]
Parameter [Strength] set to [1.2]
--- Wavelet Sharpen
Parameter [Structure Size] set to [Large]
Mask used (BASE64 PNG encoded)
--- SNR-aware Wavelet Sharpening
Parameter [Protection] set to [Shadow/Highlights]
Parameter [Scale 1] set to [100 %]
Parameter [Scale 2] set to [100 %]
Parameter [Scale 3] set to [100 %]
Parameter [Scale 4] set to [100 %]
Parameter [Scale 5] set to [100 %]
Parameter [Mask Fuzz] set to [4 pixels]
Parameter [Amount] set to [300 %]
Parameter [High SNR Size Bias] set to [85 %]
Parameter [Low SNR Size Bias] set to [0 %]
Parameter [Dark/Light Enhance] set to [50% / 50%]
Mask used (BASE64 PNG encoded)
--- Spatially Variant PSF Deconvolution
Parameter [PSF Resampling] set to [None]
Parameter [Synthetic PSF Model] set to [Moffat Beta=4.765 (Trujillo) (Atmosphere)]
Parameter [Sampled PSF Area] set to [15x15]
Parameter [Synthetic PSF Radius] set to [1.5 pixels]
Parameter [Synthetic Iterations] set to [10x]
Parameter [Spatial Error] set to [1.00]
Parameter [Deringing Fuzz] set to [25.0 pixels]
Parameter [Deringing Detect] set to [65 %]
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 [0.80]
--- Color
Parameter [Bias Slider Mode] set to [Sliders Reduce Color Bias]
Parameter [Style] set to [Artistic, Not Detail Aware]
Parameter [LRGB Method Emulation] set to [RGB Ratio, CIELab Luminance Retention]
Parameter [Matrix] set to [HOO Duoband 100R,50G+50B,50G+50B]
Parameter [Dark Saturation] set to [7.1]
Parameter [Bright Saturation] set to [7.4]
Parameter [Saturation Amount] set to [258 %]
Parameter [Blue Bias Reduce] set to [1.00]
Parameter [Green Bias Reduce] set to [1.00]
Parameter [Red Bias Reduce] set to [1.26]
Parameter [Mask Fuzz] set to [1.0 pixels]
Parameter [Cap Green] set to [0 %]
Parameter [Highlight Repair] set to [10 pixels]
--- Super Structure
Parameter [Detail Preservation] set to [Linear Brightness Mask Darken]
Parameter [Compositing Algorithm] set to [Multiply, Gamma Correct]
Parameter [Brightness, Color] set to [Process Both]
Parameter [Brightness Retention] set to [Local Median]
Parameter [Mask Fuzz] set to [1.0 pixels]
Parameter [Airy Disk Radius] set to [50 %]
Parameter [Gamma] set to [0.75]
Parameter [Detail Preservation Radius] set to [20.0 pixels]
Parameter [Saturation] set to [50 %]
Parameter [Strength] set to [100 %]
--- Unified De-Noise
Parameter [Grain Size] set to [6.0 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 [75 %]
Parameter [Equalized Grain] set to [0 %]
Parameter [Scale Correlation] set to [12 %]
Parameter [Color Detail Loss] set to [50 %]
Parameter [Brightness Detail Loss] set to [50 %]
Parameter [Grain Dispersion] set to [6.0 pixels]
--- Photographic Film Development Emulation
Parameter [White Calibration] set to [Use Stars]
Parameter [Gamma] set to [0.50]
Parameter [Skyglow] set to [0 %]
Parameter [Digital Development] set to [Off]
Parameter [Blue Luminance Contrib.] set to [100 %]
Parameter [Green Luminance Contrib.] set to [100 %]
Parameter [Red Luminance Contrib.] set to [100 %]
Parameter [Dark Anomaly Headroom] set to [5 %]
Parameter [Dark Anomaly Filter] set to [6.0 pixels]
--- Crop
Parameter [X1] set to [0 pixels]
Parameter [Y1] set to [54 pixels]
Parameter [X2] set to [2911 pixels (-0)]
Parameter [Y2] set to [1885 pixels (-0)]
Image size is 2911 x 1831
File saved [D:\POST-PROCESSING\NGC6960 Sept 2021 proc\West Veil first image i7 Envy.tiff].

West Veil first image i7 Envy.jpg (469.95 KiB) Viewed 5161 times

[firebrand18]

Thanks for posting the log and process steps; nice job on the Veil, looks great. I had the L-Enhance and used it extensively then traded-in for L-Extreme.

I find not all subjects are treated the same in StarTools; some benefit from Contrast, HDR, Sharp, Decon, SS, others not so much. I switch back-and-forth between Wipe and Autodev until happy with the result (laying the "foundation"), then switch between Autodev and Color skipping everything in between initially until satisfied with how the color may end up looking, then go back and dive into the detail enhancement.

I like your Dev gamma/skyglow suggestion after final denoise. Can make a nice final touch on throttling sky background, enhancing shadow detail, toning down brightness, etc.

Here is an example of Gamma Cygni (Sadr) region I imaged last week with L-Extreme (4hrs); same work flow for both except v1 has no HDR, Sharp or Decon, whereas v2 has the full treatment; I like both but find v1 has a nice soft feel to it. So many variations you can get into.

Cheers.

[happy-kat]

i just had a play with the jpg and to correct the sky background (I did not use wipe as I did not have the linear data) I used superstructure and Isolate, then I used colour module and reduced brightness saturation and then picked legacy, I repeated this nodule three times and this sorted the blueness of the bottom third of the image. Then shrink with classic and then noise reduction. Lastly filmdev only to lift the sky glow by 1 to push the histogram peak right a nudge. It is is not perfect as I suspect a judicious use of a mask would have preserved the nebula colour.

NGC 6992 2021-07-23-09-03 240s 1x1 10 50 -5C 6h40m v2 2.jpg (106.82 KiB) Viewed 5120 times