Aug 7, 2026

My Image of the Sadr region in the center of Cygnus

🔭 Project Summary

Target: The Sadr Region — IC 1318 / Sh2-108 / Gamma Cygni Nebula complex

Capture Dates: July 11, 12, 22, and 23, 2026

Constellation: Cygnus • Distance: ≈ 4,500–5,000 light-years for the nebular complex; Sadr ≈ 1,800 light-years

Type: Wide-field emission nebula complex with dark molecular clouds, bright nebulae, young stars, and open cluster NGC 6910

Imaging Period: July 11–23, 2026 • Total Integration: 12 h 46 m 00 s (SHO narrowband + RGB stars)

Filters: Ha · OIII · SII (Astronomik 36 mm 6 nm) + R · G · B (ZWO 36 mm LRGB Gen II)

Telescope: Askar FRA400 72 mm f/5.6 Quintuplet Air-Spaced Astrograph

Camera: ZWO ASI2600MM-Pro (−10 °C; Gain 100 narrowband, Gain 0 RGB)

Mount: ZWO AM5 on custom steel pier

Processing: PixInsight (SHO narrowband + RGB stars) & Photoshop

Location: Whispering Skies Observatory · Honeoye Falls, NY (USA)

Acquisition Notes: Ha: 44 × 300 s; OIII: 41 × 300 s; SII: 46 × 300 s; R: 37 × 60 s; G: 37 × 60 s; B: 37 × 60 s, all bin 1×1 at −10 °C; total 12 h 46 m 00 s after culling bad or questionable subs.

Image Note: This wide-field SHO narrowband image frames the Sadr / Gamma Cygni region, including IC 1318, Sh2-108, NGC 6910, Lynds bright and dark nebulae, and Barnard dark nebulae across the dense Cygnus Milky Way.

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Special Note

Welcome to the New Image Processing Page for this project! You got here by following a link in the main Image Project Report, and you can easily return to that by using the back button on your browser.

Abbreviations Used

ACM Astro Color Mixer Script

ACE Astro Contrast Enhancer Script

BXT BlurXTerminator by RC-Astro

CC Cosmetic Correction

CT Curves Transformation Process

DBE Dynamic Background Extraction Process

ET Exponential Transformation

HT Histogram Transformation

NXT NoiseXTerminator by RC-Astro

MLT Multiscale Linear Transform

PI PixInsight

PS Photoshop

SCNR Subtractive Chromatic Noise Reduction Process

‍ ‍SFS SubFrameSelector

SPCC SpectroPhotometric Color Calibration

STF Screen Transfer Function

STF->HT method – Drag the STF triangle to the base of HistogramTransformation, then apply it to the image to take it nonlinear.

SXT StarXTerminator by RC-Astro

WBPP Weighted Batch Preprocessing Script

Sadr Region SHO + RGB Stars Processing Flow

Sequential summary of the actual Sadr Region workflow, following the published processing walkthrough from Blink review and WBPP 3.01 integration through SHO/RGB master construction, linear correction, star separation, GHS stretching, masked SHO color and contrast work, RGB star recombination, and final Photoshop output.

1. Blink Review and Frame Culling

1. Review All Lights Inspected Ha, OIII, SII, R, G, and B frames; there were many satellite tracks, but they were easy to handle

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2. Cull Narrowband Frames Removed 10 Ha frames, 12 OIII frames, and 3 SII frames for focus, tracking, or clouds

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3. Keep RGB Frames No Red, Green, or Blue frames were removed after review

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4. Check Calibration Frames Darks, dark flats, and flats all looked suitable for processing

2. WBPP 3.01 Calibration and Integration

5. Load WBPP Data Reset WBPP, loaded all lights, flats, and darks, and selected the output directory

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6. Configure WBPP Used maximum quality, automatic reference image, automatic pedestal, cosmetic correction for all lights, and autocrop

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7. Set Exposure Tolerances Set dark and light exposure tolerances to 0 so calibration matched the exposure groups precisely

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8. Run Integration WBPP ran in about 1 hour 52 minutes; despite odd summary-screen errors, the master frames looked good

3. Master Image Setup

9. Load Master Frames Loaded and renamed the integrated Ha, OIII, SII, R, G, and B master images

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10. Build SHO Image Used ChannelCombination to create the master SHO color image from the narrowband masters

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11. Build RGB Image Used ChannelCombination to create the master RGB image for natural star color

4. Initial Linear SHO Processing

12. Skip DBE No obvious gradients were visible in the master SHO image, so DBE was not used on the SHO data

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13. BXT Correct Only Ran BlurXTerminator in correct-only mode to clean up corner stars; the FRA400 field was already very crisp

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14. Measure Stars Used the PFSImage script to measure star sizes: X = 2.49 and Y = 2.32

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15. Full BXT Ran full BlurXTerminator with enhanced values, roughly double the measured star sizes, to shrink and refine the star field

16. NXT V3 Applied NoiseXTerminator V3 to clean the linear SHO image before star removal

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17. SXT Star Removal Ran StarXTerminator on the SHO image and did not keep the SHO stars

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18. NarrowbandNormalization Ran NarrowbandNormalization on the SHO starless image using the project-specific settings shown in the walkthrough

5. Linear RGB Star Processing

19. DBE on RGB Ran DynamicBackgroundExtraction on the linear RGB image using subtraction and samples placed to avoid the nebulae

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20. BXT Correct Only Used BlurXTerminator correct-only to clean up the RGB corner stars

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21. SPCC Selected a background preview and ran SPCC with the Ideal curve and ZWO R, G, and B filter curves

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22. Measure RGB Stars Used PFSImage to measure RGB star sizes: X = 2.34 and Y = 2.19

23. Full BXT Ran full BlurXTerminator with enhanced star-shrinking values based on the measured RGB star sizes

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24. NXT V3 Applied NoiseXTerminator V3 to the cleaned and calibrated RGB image

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25. SXT for RGB Stars Ran StarXTerminator and kept the RGB star image for later recombination; the RGB starless image was not used

6. Take RGB Stars Nonlinear

26. Star Stretch Script Used Seti Astro Star Stretch to take the RGB star image nonlinear

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27. Star Version 1 Created a first star image using stretch 5.0 and color boost 1.6

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28. Star Version 2 Created a second, stronger star image using stretch 7.0 and color boost 1.79

7. Take the Starless SHO Image Nonlinear

29. GHS Stretch Used GeneralizedHyperbolicStretch to take the SHO starless image nonlinear

8. Mask Construction for Nonlinear SHO Work

30. Create WarmMask Used ColorMask from hue 328 to 68 with blur 5, then boosted the mask with CurvesTransformation

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31. Create CoolMask Used ColorMask from hue 162 to 259 with blur 5, then boosted the mask with CurvesTransformation

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32. Prepare Local Color Control Built the mask structure used for separate warm-region and cool-region color, saturation, and contrast work

9. Nonlinear SHO Color, Tone, and Contrast

33. Base CT Work Used CurvesTransformation to set the basic tone scale and color saturation

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34. SCNR Green Passes Applied SCNR Green at 0.9, inverted the image, applied SCNR Green at 0.9 again, then inverted back

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35. WarmMask Refinement Applied WarmMask, adjusted color and saturation with CT, then used LHE at 64 and 216 scales for fine and coarse structure

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36. CoolMask Refinement Applied CoolMask and used CT to tune the cool-color saturation and balance

37. Astro Color Mixer Used Astro Color Mixer for small saturation, per-color luminance, and slight color-rotation tweaks

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38. Final CT Pass Applied another CurvesTransformation pass for final tone scale and color tuning

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39. Astro Contrast Enhancer Tested ACE with Texture 100, Clarity 49/10, and Dehaze 0; then reduced Texture to 75 for a more natural result

10. Add RGB Stars Back In

40. ScreenStars Recombination Used the ScreenStars script to add RGB stars back into the processed SHO starless image

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41. Compare Star Versions Tested the available star versions against the SHO nebula image

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42. Select Final Stars Chose star image #1 because the heavier star version distracted from the nebulosity

11. Photoshop Polish and Final Output

43. Export TIFF Saved the PixInsight result as a 16-bit unsigned TIFF and moved it to Photoshop

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44. Add Watermarks Added the project watermark and presentation finishing touches

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45. Final JPEG Exports Exported clear, watermarked, and web-sized JPEG versions for publication and sharing

Processing this Image

(All Processing is done in PixInsight, with some final touches done in Photoshop)

1. Blink

General
- Lots of satellite tracks - easy to handle
Ha
- 10 frames removed - 6 for focus, 2 for tracking, 2 for clouds
OIII
- 12 frames removed, 6 for focus, 2 for tracking, 4 for clouds
SII
- 3 frames removed, 1 for tracking, 2 for clouds
Red
- No frames removed!
Green
- No frames removed!
Blue
- No frames removed!
Darks
- All looks OK
Dark Flats
- All looks OK
Flats
- All good

2. WBPP 3.01

Reset everything
Load all lights
Load all flats
Load all darks
Select - maximum quality
Reference Image - auto - the default
Select the output directory for the WBPP folder
Enable CC for all light frames
Pedestal value - auto
Darks - set exposure tolerance to 0
Lights - set exposure tolerance to 0
Lights - all set except for a linear defect
set for Autocrop
WBPP ran for 1:52. The summary screen was empty and displayed errors, but they did not appear to affect the output; the masters looked great.

3. Load Master Images and Create Color Images

Load all master images and rename them.
Using ChannelCombination, create the Master SHO and RGB color images

4. Initial Process of Linear SHO data

There were no obvious gradients in the Master SHO image, so I did not run DBE.
Run BXT - correct only. This cleans up the stars at the corners. Not much to do in this image as the scope is very crisp.
Run PFSImage script to measure star sizes. X = 2.49 Y = 2.32. This will influence the values used in BXT.
Run Full BXT - I am using an enhanced set of values to shrink stars more. These are about double the measured star sizes. See the BXT Panel Snapshot below.
Run NXT V3 - see params from snapshot below.
Run SXT and don’t save the SHO stars. I will be using RGB stars so there is no need to keep them.
Run NarrowbandNormalization (see screenshot below for parameters used)

Before BXT

BXT Correct Only

BXT Full

After NXT V3

Master SHO Before BXT Correct Only, After BXT Correct Only, After BXT Full, After NXT

After NBNormalization (click to enlarge)

5. Process the Linear RGB Data

Run DBE for the RGB linear image. Use subtraction for the correction method. Choose a sampling plan that avoids the nebulae (see below)
Run BXT - correct only. This cleans up the stars at the corners. Not much to do in this image as the scope is very crisp.
Select a preview rectangle that samples the background sky, and then set up and run SPCC.
- Use the Ideal curve
- Use ZWO R, G, & B filter curves,
Run the PFSImage script to measure star sizes. X = 2.34, Y = 2.19. This will influence the values used in BXT.
Run Full BXT - I am using an enhanced set of values to shrink stars more. These are about double the measured star sizes. See the BXT Panel Snapshot below.
Run NXT V3 - see params from snapshot below.
Run SXT and don’t save the RGB starless image.

Before BXT

BXT Correction Only

BXT Full

After NXT V3

Master RGB before BXT Correct Only, After BXT Correct Only, After BXT Full, After NXT V3

Final Master RGB image - Before Star Removal.

6. Take RGB Stars Nonlinear

Use Seti Astro Star Stretch Script to stretch Stars
I decided to create two versions of the nonlinear star image. I created two nonlinear star versions: one using the default stretch and one using a stronger stretch:
- Stars #1 used a stretch of 5.0 (the default) and a color boost of 1.6
- Stars # 2 used a stretch of 7.0 and a color boost of 1.79

Star Stretch Script panel and params used for stars #1

7. Take the Starless SHO Image Nonlinear

Use GHS to take the SHO starless image nonlinear - see screenshot below for params.

8. Process the Nonlinear SHO Starless Image

This is the big meaty step of this process. In this section, I will focus on getting Green/Magena under control, nailing the tone scale and color separation, doing masked warm/cool refinement, and then ACM/ACE polish.

Create the WarmMask
- Use the ColourMask Process with Star Hue 328 and an end hue of 68, with a blur of 5
- Apply CT to boost the mask
Create the CoolMask
- Use the ColourMask Process with Star Hue 162 and an end hue 259, with a blur of 5
- Apply CT to boost the mask
Apply CT to set the basic tone scale and color saturation
Apply SCNR Green with a value 0.9 to reduce the amount of green in the image.
Invert the image (make magenta regions look green)
Apply SCNR Green with a value 0.9 to reduce the amount of green in the image.
Invert the Image
Apply CT for Tone and Color.
Apply the Warm Mask
- Apply CT to adjust color and saturation
- Apply LHE with a factor of 64, contrast limit of 2.0, an amount of 0.4, and a histogram of 8 bits (This will bring up some finer detail)
- LHE with a factor of 216, contrast limit of 2.0, and an amount of 0.3, and a histogram of 8 bits (This will bring up some coarser detail)
Apply the CoolMask
- Apply CT and adjust cool-color saturations
At this point, colors are pretty close to what I want, but I am going to finalize them further using my Astro Color Mixer Tool. These were small tweaks to saturation, per-color luminance, and a few slight color rotations.
Now do a CT for tone scale and color tweaks.
Now I want to optimize contrast. I used my new Astro Contrast Enhancer tool for this.
- I pegged the texture at 100 - it seemed like this image could handle this much of an adjustment
- I added clarity at 49/10
- I did not think that Dehaze added much here and left that at zero.
I assessed the final image, and my sense was that the image looked very sharp - but perhaps TOO sharp. I was starting to see some artifacts. So I undid that and went back in and redid the adjustments by taking Texture down to 75 and leaving clarity alone. I think this really helped make the image look more natural.

Backing off ACE texture by 25% (click to enlarge)

9. Add the Stars Back In

Using the ScreenStars Script, add stars back into our SHO starless image. Do this two times with the two star images created
Pick the best one. I went with star image #2 because I think you need the heavier stars to standout in the rich nebulosity in the image.

The script used to add the images back in - with smaller stars.

The smaller stars just don’t work here - they are lost in the complexity of the region,.

The larger stars work much better - Final Image ready for rendering.

10. Export the Image to Photoshop for Polishing

Save the image as a 16-bit unsigned TIFF and move it to Photoshop
Added Watermarks

Export Clear, Watermarked, and web-sized JPEGs.

11. The Final Image!

11. Final Comments

I was happy with this process. ACM and ACE eliminated several manual steps, and both tools seemed to do their job well. This is the kind of image that it really pays off to zoom into and pan around - a lot of stuff going on in this region, and the image has very crisp details - especially of the dark dust!

Back to the Main Sadr Region 2026 Page

Alternatively, you can use the back arrow to return to the Main Sadr Region page, or you can use the menu at the top of the page to continue your navigation.

Thanks,

Pat

The Sadr Region of Cygnus 2026: Image Processing Walkthrough

🔭 Project Summary

Special Note

Abbreviations Used

Sadr Region SHO + RGB Stars Processing Flow

Processing this Image

1. Blink

General

Ha

Red

Green

Blue

Darks

Dark Flats

2. WBPP 3.01

3. Load Master Images and Create Color Images

4. Initial Process of Linear SHO data

5. Process the Linear RGB Data

6. Take RGB Stars Nonlinear

7. Take the Starless SHO Image Nonlinear

8. Process the Nonlinear SHO Starless Image

This is the big meaty step of this process. In this section, I will focus on getting Green/Magena under control, nailing the tone scale and color separation, doing masked warm/cool refinement, and then ACM/ACE polish.

9. Add the Stars Back In

10. Export the Image to Photoshop for Polishing

11. The Final Image!

11. Final Comments

Hickson 61 - The Box - 2026 Image Processing Walkthrough.