SH2-88 - A Tulip-Like Nebula in Vulpecula: Image Processing Walkthrough

Written By Patrick A. Cosgrove

September 27, 2026

My Image of the SH2-88 region.

This page is the mage Processing Walkthrough page for the SH2-88 2026 Imaging Project

🔭 Project Summary

Target: SH2-88 — Sharpless 88 / LBN 139 / LBN 061.50+00.29 / [TP72] 67

Capture Dates: September 6, 11, and 14, 2026

Constellation: Vulpecula • Distance: ≈ 7,500–7,800 light-years

Type: H II emission complex containing diffuse, compact, and ultracompact star-forming regions

Imaging Period: September 6–14, 2026 • Total Integration: 12 h 22 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: William Optics 132 mm f/7 FLT APO Refractor with P-FLAT7A 0.8× reducer/flattener

Camera: ZWO ASI2600MM-Pro (−15 °C; Gain 100 narrowband, Gain 0 RGB)

Mount: iOptron CEM60 on custom steel pier

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

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

Acquisition Notes: Ha: 48 × 300 s; OIII: 47 × 300 s; SII: 49 × 300 s; R: 14 × 30 s; G: 15 × 30 s; B: 15 × 30 s. All frames were captured bin 1×1 at −15 °C; total integration is 12 h 22 m 00 s after culling bad or questionable subs.

Image Note: This SHO narrowband image with RGB stars frames the SH2-88 complex in Vulpecula. The field includes the large diffuse nebula SH2-88A, the compact cometary H II region SH2-88B1, and the deeply embedded ultracompact H II region SH2-88B2—three distinct stages of massive-star formation visible within one remarkable region.

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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 CurvesTransformation Process

    DBE DynamicBackgroundExtraction Process

    ET Exponential Transformation

    HT HistogramTransformation Process

    NXT NoiseXTerminator by RC-Astro

    MLT MultiscaleLinearTransform Process

    PI PixInsight

    PS Photoshop

    SCNR Subtractive Chromatic Noise Reduction Process

    ‍ SFS SubframeSelector

    SPCC SpectroPhotometric Color Calibration

    STF ScreenTransferFunction

    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

    SH2-88 SHO + RGB Stars Processing Flow

    Sequential summary of the actual SH2-88 workflow, following the published SH2-88 image-processing walkthrough: frame review, WBPP 3.01 integration, SHO and RGB master construction, separate linear processing, prototype RGB-star stretching, masked nonlinear SHO work, star recombination, and final Photoshop output.

    1. Blink Review and Frame Culling
    1. Review All Lights Inspected the Ha, OIII, SII, R, G, and B frames for clouds, tracking problems, aircraft, and other defects.
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    2. Review Narrowband Data No Ha, OIII, or SII frames were removed. The channels showed limited signal outside the main nebular structures.
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    3. Review RGB Data No Red or Green frames were removed. One Blue frame was rejected because of clouds.
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    4. Check Calibration Frames Darks, dark-flats, and flats all appeared suitable for calibration and integration.
    2. WBPP 3.01 Calibration and Integration
    5. Load WBPP Data Reset WBPP, loaded the light, flat, and dark frames, and selected the output directory.
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    6. Configure WBPP Selected maximum quality, automatic reference images, automatic pedestal, Cosmetic Correction for all lights, and autocrop.
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    7. Set Exposure Tolerances Set the dark- and light-frame exposure tolerances to 0 so calibration matched each exposure group precisely.
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    8. Run Integration WBPP completed in 37 minutes, 51 seconds with no errors.
    3. Master Image Construction
    9. Load Master Frames Loaded and renamed the integrated Ha, OIII, SII, R, G, and B master images.
    →
    10. Build the SHO Master Used ChannelCombination to create the SHO color image from the three narrowband masters.
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    11. Build the RGB Master Used ChannelCombination to create the RGB image that would supply the natural-color stars.
    4. Initial Linear SHO Processing
    12. DynamicBackgroundExtraction Applied DBE to the linear SHO image using a sampling plan that avoided the principal nebular structures.
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    13. BXT Correct Only Ran BlurXTerminator in correct-only mode to clean up the corner stars; little correction was needed with the WO132 data.
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    14. Determine BXT Settings PFSImage was unavailable after the PixInsight 1.9.5 upgrade, so the appropriate star settings were determined through iterative testing.
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    15. Full BXT Applied the final BlurXTerminator settings selected from the iterative comparisons.
    16. NXT V3 Applied NoiseXTerminator V3 to clean the linear SHO master.
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    17. Remove Narrowband Stars Ran StarXTerminator and discarded the SHO stars because RGB stars would be used in the final image.
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    18. NarrowbandNormalization Applied NarrowbandNormalization to the starless SHO image using the project-specific settings shown in the walkthrough.
    5. Linear RGB-Star Processing
    19. RGB DBE Applied DBE with subtraction, placing samples in background areas that avoided the visible nebulosity.
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    20. BXT Correct Only Ran BlurXTerminator in correct-only mode to clean up the RGB corner stars.
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    21. SPCC Used a background preview and ran SPCC with the Ideal reference curve and the ZWO R, G, and B filter curves.
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    22. Determine RGB BXT Settings With PFSImage unavailable, the full RGB BXT settings were selected through iterative visual testing.
    23. Full RGB BXT Applied the selected full BlurXTerminator settings to refine the RGB star field.
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    24. RGB NXT V3 Applied NoiseXTerminator V3 to the linear RGB image.
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    25. Extract RGB Stars Ran StarXTerminator, retained the RGB star image, and discarded the RGB starless result.
    6. Stretch the RGB Stars
    26. Use the Prototype Tool Used the prototype star-stretch utility developed during this project to take the RGB stars nonlinear.
    →
    27. Create Three Star Versions Created smaller, medium, and larger star fields with the Star Presence control set to 25, 50, and 75.
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    28. Preserve Star Color Left the color-saturation setting unchanged while varying only the stars’ presence and apparent size.
    7. Take the Starless SHO Image Nonlinear
    29. STF to Histogram Used the STF→HistogramTransformation method to stretch the starless SHO image into the nonlinear state.
    8. Construct the Nonlinear Processing Masks
    30. Create the WarmMask Used ColourMask with Start Hue 331, End Hue 72, and Blur 5; then strengthened the result with CurvesTransformation.
    →
    31. Create the CoolMask Used ColourMask with Start Hue 169, End Hue 270, and Blur 5; then strengthened the result with CurvesTransformation.
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    32. Create the Initial RangeMask Used RangeSelection at 0.5–1.0 with Blur 5 to isolate the two bright compact features, then cleaned the mask with CloneStamp.
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    33. Create RangeMask2 Created a second range mask that isolated only the highest-exposure areas for controlled sharpening.
    9. Nonlinear SHO Color, Tone, and Detail
    34. Establish the Base Image Used CurvesTransformation to establish the initial tone scale and color saturation.
    →
    35. Control Green and Magenta Applied SCNR Green at 0.85, inverted the image, repeated SCNR Green at 0.85, and inverted back.
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    36. Refine Warm and Cool Regions Applied separate CurvesTransformation color and saturation adjustments through the WarmMask and CoolMask.
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    37. Protect the Bright Features Applied CurvesTransformation through the inverted RangeMask to adjust the broader tone scale while protecting the brightest nebular structures.
    38. Astro Color Mixer Used Astro Color Mixer to fine-tune the warm and cool color positions.
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    39. ACE and NXT Applied light Clarity and Dehaze with Astro Contrast Enhancer, followed by NoiseXTerminator cleanup.
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    40. Targeted Photoshop Work Used feathered lasso selections in Photoshop for localized color and tone-scale adjustments.
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    41. Final CT and MLT Applied a final CurvesTransformation adjustment, then used MLT sharpening through RangeMask2 on the brighter detail regions.
    10. Add the RGB Stars Back In
    42. ScreenStars Tests Used ScreenStars to combine each of the three RGB-star versions with the processed starless SHO image.
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    43. Compare Star Presence The smallest stars became lost in the complex field, while the largest version made the brighter stars too prominent.
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    44. Build the Final Star Version Created Star Version 4 with StarStretch, splitting the difference between Versions 2 and 3 without introducing the halos seen in an earlier test.
    11. Photoshop Polish and Final Output
    45. Light Final Polish Kept the final Photoshop work restrained and slightly reduced the orange and blue saturation.
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    46. Refine the Composition Cropped the upper and left sides slightly to place greater emphasis on the main SH2-88 nebula.
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    47. Prepare Publication Files Saved the processed image as a 16-bit unsigned TIFF and added the project watermark.
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    48. Export Final Versions Exported clear, watermarked, and web-sized JPEG files for publication and sharing.

    Processing this Image

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

    1. Blink

    • Ha

      • No frame removed

    • OIII

      • No frames removed - very little signal seen.

    • SII

      • No frames removed - some weak signal

    • Red

      • No frames removed

    • Green

      • No frames removed

    • Blue

      • 1 frame removed - Clouds

    • 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 37:51. No errors.

    WBPP Calibration View

    WBPP Post Calibration View

    WBPP Pipeline View

    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

    Master Ha, OIII, and SII Images

     

    Master SHO image.

     

    Master R, G, and B images

     

    Master RGB color image.

     

    4. Initial Process of Linear SHO data

    • DBE was run on the SHO image - see details in images 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.

    • I just upgraded to Pixinsight 1.9.5 and for some reason my PFSImage script is no longer showing. So I usually use it at this point to extract star sizes for my BXT runs. This time I will go without and just try to iteratively determine what I need.

    • Run Full BXT - I experimented and came up with what you see below. See the BXT Panel Snapshot below.

    • Run NXT V3 - see params from snapshot below.

    • Run SXT and remove stars - we are not going to use the narrowband stars, so no need to save them.

    • Run NarrowbandNormalization (see screenshot below for parameters used).

    SHO DBE Sampling Plan (click to enlarge)

    SHO DBE before image. (click to enlarge)

    SHO After DBE (click to enlarge)

    SHO DBE Background (click to enlarge)

    BXT Settings Used. (click to enlarge)

    NXT Panel used. (click to enlarge)

    Master SHO comparison: before BXT, after correct-only BXT, after full BXT and after NXT

    Master SHO Image (click to enlarge)

    NarrowbandNormalization Parameters used.

    After SXT (click to enlarge)

    SHO Starless Image after Narrowband Normalization.

    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,

    • I just upgraded to Pixinsight 1.9.5 and for some reason my PFSImage script is no longer showing. So I usually use it at this point to extract star sizes for my BXT runs. This time I will go without and just try to iteratively determine what I need.

    • Run Full BXT -Final params determined by iterative testing. See the BXT Panel Snapshot below.

    • Run NXT V3 - see params from snapshot below.

    • Run SXT and don’t save the RGB starless image - we are not going to use that one.

    Master RGB DBE Sampling Plan (click to enlarge)

    Before DBE (click to enlarge)

    Master RGB after DBE (click to enlarge)

    Master RGB Background subtracted (click to enlarge)

    Params used for BXT

    NXT Params used.

     

    SPCC Panel settings. (click to enlarge)

    SPCC Regression Results.

    After SPCC (click to enlarge)

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

    Final Master RGB image - Before Star Removal.

    Master RGB Star image after SXT.

    6. Take RGB Stars Nonlinear

    • This section represents a HUGE change for me. I have been building my own utility to handle star stretching, and it was far enough along that I wanted to use the prototype for this image. This new tool not only gives you control over how your stars are stretched, but it also allows you to inspect stars and compare stretch settings to get the effect you want.

    • I will show a few screenshots of the prototype below. But what I did here primarily was create three versions of the stretched star image - with stars that are smaller, medium-sized, and larger. The tool automatically creates a good stretch, then provides sliders to adjust Star Presence and color saturation. For this project, I left color saturation alone and used the star presence slider (which goes from 0 to 100) at values of 25, 50, and 75.

    Overall screenshot of the prototype tool. (click to enlarge)

    he Star Inspector provides several ways to evaluate a star. Here, the horizontal intensity profile is displayed. (click to enlarge)

    You can also see a 3D profile of the star that can be freely rotated. (click to enlarge)

    The individual red, green and blue intensity profiles can also be inspected. (click to enlarge)

    Nonlinear stars at the 25 Star Presence setting.

    Nonlinear stars at the 50 Star Presence setting (the default)

    And finally - at the Star Presence setting of 75

    7. Take the Starless SHO Image Nonlinear

    • Apply the STF-derived stretch to create the initial nonlinear SHO image using the STF→HT method

    Nonlinear SHO image

    8. Process the Nonlinear SHO Starless Image

    • Create the WarmMask

      • Use the ColourMask Process with StartHue 331 and an end hue of 72, with a blur of 5

      • Apply CT to boost the mask

    • Create the CoolMask

      • Use the ColourMask Process with Start Hue 169 and an end hue of 270, with a blur of 5

      • Apply CT to boost the mask

    • Apply CT to set the basic tone scale and color saturation

    • Create the Initial RangeMask

      • Use RangeSelect to isolate the two bright features to the bottom left of the main nebula. Use a low range of 0.5, a high range of 1.0, and a blur of 5.

      • Use Clone Stamp to clean up the mask

    • Create RangeMask2 to isolate the higher-exposure areas.

    • Apply SCNR Green at 0.85 to reduce green in the image.

    • Invert the image (make magenta regions look green)

    • Apply SCNR Green with a value of 0.85 to reduce the amount of green in the image.

    • Invert the Image

    • Apply the Warm Mask

      • Apply CT for color and saturation

    • Apply the CoolMask

      • Apply CT for color and saturation

    • Apply the Inverse of the RangeMask

      • Apply CT. Adjust the tone scale for the whole image, leaving the bright nebula areas alone.

    • Use Astro Color Mixer (ACM) to fine-tune color position.

    • Use Astro Contrast Enhancer (ACE ) to do some light Clarity and Dehaze

    • Apply NXT (see params).

    • Export Image to Photoshop - I wanted to work on specific areas with the lasso tool

    • Apply CT

    • Apply MLT Sharpening to just the higher exposure areas using RangeMask2.

    Params used to create the initial WarmMask

    Params used to create the initial WarmMask

    Initial RangeMask (Click to enlarge)

    Create High Epxosure Range Mask

    Initial WarmMask (click to enlarge)

    WarmMask after CT Boost (click to enlarge)

    Initial CoolMask (click to enlarge)

    After CT boost. (click to enlarge)

     

    After CloneStamp Cleanup (click to enlarge)

     

    Initial SHO image(click to enlarge)

    Apply CT (Click to enlarge)

    Apply SCNR Green (click to enlarge).

    After SCNR Green at 0.85 (click to enlarge)

    CT with WarmMask (click to enlarge)

    After CT with inverted RangeMask (click to enlarge)

    After ACM (click to enlarge)

    After ACE(click to enlarge)

     

    After NXT (click to enlarge)

    FInal CT Tweak (click to enlarge)

    Invert the image (click to enlarge)

    Final Invert (click to enlarge)

    CT with CoolMask (click to enlarge)

    Use Astro Color Mixer to fine tune color. (click to enlarge)

     

    Use ACE to tweak contrast (click to enlarge)

     

    NXT Params used in the next step (click to enlarge)

    After PS use of lasso for selected color and tone scale boosts (click to enlarge)

     

    MLT sharpening Params used

     

    After Sharpen with RangeMask2 (click to enlarge)

    9. Add the Stars Back In

    • Using the ScreenStars Script, add stars back into our SHO starless image. Do this three times with each of the star images created

    • Pick the best one. I went with star image #2 because in #1, the stars were kind of lost, and in #3, the stars were starting to dominate too much. The middle option seems best.

    Stars #1: The smaller stars just don’t work here - they are lost in the complexity of the region.

    Stars #2: The middle-sized stars are not bad.

    Stars #3: The largest size. - this too looked good but I thought that the tare were perhaps too prominent.

    10. Export the Image to Photoshop for Polishing

    • Exported the combined image from PixInsight as a 16-bit unsigned TIFF

    • For the final image, I did little to no polishing.

    • I opened the TIFF in Photoshop

    • I backed off on the saturation of the orange nebula and a tiny bit on the blue. I like a lot of color, but I felt that perhaps I had gone a bit far.

    • Cropped the upper and left edges of the image

    • Added the watermark

    • Exported the final JPEG versions: Clear, Watermarked, and Web-sized image.

    11. The Final Image!

    The Final Image

    12. Final Comments

    Given how difficult our weather has been, I was happy to collect this data, even under less-than-ideal conditions.

    I was also pleased to image a target I had never encountered before, and I was fascinated by its resemblance to the Tulip Nebula.

    Using my prototype star-stretch tool improved the stars while also revealing areas that still need attention—a win-win.

    Back to the Main SH2-882026 Page

    Alternatively, you can use the back arrow to return to the Main SH2-88 Region page, or you can use the menu at the top of the page to continue your navigation.

    Thanks,

    Pat

    Patrick A. Cosgrove

    A retired technology geek leveraging his background and skills in Imaging Systems and Computers to pursue the challenging realm of Astrophotography. This has been a fascinating journey where Art and Technology confront the beauty and scale of a universe that boggles the mind…. It’s all about capturing ancient light - those whispering photons that have traveled long and far….

    https://cosgrovescosmos.com/
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    NGC 7129 - The Cosmic Rosebud - 2026 Image Processing Walkthrough.