Help needed with horsehead and flame neublas

[Moonstruck]

Hello,
I imaged the horsehead and flame nebulas together in one frame, and could use some advice on how to reduce the brightness of Alnitak and some of the surrounding stars. I tried adjusting most modules (including dimsmall and isolate in the superstructure module) and can't figure out how to do this. I set the ROI around the horsehead nebula, which resulted in the attached image. I also tried using no ROI, but either way the brightness of Alnitak is overpowering! Any suggestions? Or would you keep it as-is? I included links to my processed image and rough stack if you can assist.

Thanks!

Raw stack:
https://drive.google.com/file/d/1tNx1oe ... sp=sharing

Processed image:
https://drive.google.com/file/d/1xX_6Nf ... sp=sharing

[almcl]

Hi Moonstruck

Thanks for letting us have a play with your data. Alnitak does present some challenges round the Horsehead and Flame nebs, doesn't it?

I have had a play with your stack and produced the image below. Pretty sure much better is possible, but see what you think?

If it's of interest, I can post the log file section.

Alnitak+HH.jpg (139.95 KiB) Viewed 4234 times

[Moonstruck]

Hi almcl,
Thanks for processing the stack! Yes your Alnitak and surrounding stars look much better than mine. Can you attach your log file? I'm interested in learning what you did!

John

[almcl]

OK, John, here we go.

I've taken the mask details out to keep the size down. Probably the only bit worth mentioning is the mask used in the filter module. This was a circle large enough to cover most of Alnitak's glow with just a small centre circle removed and then a few presses of the button - I may have slightly overdone this as there's a noticeably dimmer circle round it.

Anything that doesn't make sense, do say?

-----------------------------------------------------------
StarTools 1.8.527MR2
Thu Nov 10 13:55:50 2022
-----------------------------------------------------------
File loaded [C:\Users\Al\Favorites\Downloads\Autosave.fits].
Image size is 3104 x 2822
---
Type of Data: Linear and was Bayered, but not whitebalanced
--- Auto Develop

Default parameters

--- Crop
Parameter [X1] set to [77 pixels]
Parameter [Y1] set to [51 pixels]
Parameter [X2] set to [2955 pixels (-149)]
Parameter [Y2] set to [2604 pixels (-218)]
Image size is 2878 x 2553
--- Rotate
Parameter [Angle] set to [180.0]
--- 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 [7 pixels]
Parameter [Gradient Falloff] set to [0 %]
Parameter [Synth. Bias Edge Area] set to [100 %]
Parameter [Gradient Aggressiveness] set to [92 %]
Parameter [Correlation Filtering] set to [Off]
--- Bin
Parameter [Scale] set to [scale 50.00% / +2.00 bits / +1.00x SNR improvement]
Image size is 1439 x 1276
Redoing stretch of linear data
--- Auto Develop
Parameter [Ignore Fine Detail <] set to [2.6 pixels]
Parameter [Outside RoI Influence] set to [9 %]
Parameter [RoI X1] set to [358 pixels]
Parameter [RoI Y1] set to [324 pixels]
Parameter [RoI X2] set to [570 pixels (-869)]
Parameter [RoI Y2] set to [519 pixels (-757)]
Parameter [Detector Gamma] set to [1.47]
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 [Medium]
Parameter [Gamma Shadow (Lift)] set to [1.14]
Parameter [Gamma Highlight (Tame)] set to [3.99]
Parameter [Gamma Smoothen] set to [20.0 pixels]
Parameter [Context Size] set to [50x50 pixels (3.47% image W, 3.92% image H)]
Parameter [Shadows Detail Boost] set to [0 %]
Parameter [Highlights Detail Boost] set to [0 %]

--- Wavelet Sharpen
default settings

PSF samples used (11 PSF sample locations, BASE64 encoded)

VFMAAAsAnwX8BCoE8gRGBBEEWQWoAvoE0gEfBAkAHQQGAc0DKAFMA+YB1ACUAqkAEQHZAAEB

--- Spatially Variant PSF Deconvolution
Parameter [PSF Resampling] set to [None]
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 [20.0 pixels]
Parameter [Deringing Detect] set to [50 %]
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]
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 [2.0]
Parameter [Bright Saturation] set to [Full]
Parameter [Saturation Amount] set to [200 %]
Parameter [Blue Bias Reduce] set to [1.18]
Parameter [Green Bias Reduce] set to [1.22]
Parameter [Red Bias Reduce] set to [1.00]
Parameter [Mask Fuzz] set to [1.0 pixels]
Parameter [Cap Green] set to [0 %]
Parameter [Highlight Repair] set to [Off]
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 [Off]
Parameter [Un-glow Strength] set to [Off]
Parameter [Un-glow Kernel] set to [Off]
Mask used (BASE64 PNG encoded)

--- Filter
Parameter [Filter Mode] set to [Reject]
Parameter [Sampling Method] set to [Single Pixel]
Parameter [Filter Width] set to [5]
Parameter [Mask Fuzz] set to [31.0 pixels]
Mask used (BASE64 PNG encoded)

--- Super Structure (Dim Small @ 100%):
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 [8.0 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 [50 %]
Parameter [Color Detail Loss] set to [50 %]
Parameter [Brightness Detail Loss] set to [50 %]
Parameter [Grain Dispersion] set to [8.0 pixels]
File saved [E:\Astronomy\questions for startools\Alnitak+HH.jpg].

[Moonstruck]

Thanks for the log, I appreciate it!

[Mike in Rancho]

Gave it a bit of a try, John. Not sure how well I did.

Not too easy a target, even beyond Alnitak, in broadband. There's a bit of dusty stuff around here, which you may just be picking up on, but sort of lower SNR so trouble for me to keep from getting choppy.

As well as purple. So I kept the star sampled channel settings (after excluding Alnitak) but changed up to RGB ratio, which helped a bit in that regard. For saturation I upped the dark and lowered the bright, to take some emphasis away from the killer star there.

Also before ST I ran this through DSS again just for the RGB alignment, to try to help out with the color dispersion.

For taming Alnitak, which maybe I really didn't?, I just used a ROI and big IFD. Tough balance here, keeping that star under control, but not wanting to be too dark, yet also not wanting to raise the level of outer choppiness. Fairly normal otherwise. No SS, just DN after Color.

I did fiddle with the gamma a bit at the end to try to get the overall look/contrast where I wanted, and because the pixels were 100% blown I did at a mild layer blur to the core of Alnitak as the last step. Still pretty crazy bright though.

The wattage could probably be turned down here a little bit more, though that might start losing some definition in the lower portions of the horsey.

MS Autosave001 RGB Aligned ST8 1D.jpg (438.23 KiB) Viewed 4173 times

[Moonstruck]

Thanks Mike. Your version looks a lot better than mine and you seemed to find the right balance. Seems like this is a tough target and there is no way to completely get around Alnitak's dazzling brightness, aside from completely covering it up/eliminating it from the picture, but I don't want to do that as that would detract too much from reality. I'm not sure I want to fiddle with it any more though. I think the next time I image this I'm going to decrease the exposure time to maybe 30 sec to try to tame Alnitak a little more, but not sure if that would also decrease the nebulosity of the flame and horsehead too much? I guess it will take some trial and error. Thanks for the tips. Hope your planetary imaging is going well these days.