April 17, 2026

My April 2026 image of M81/82 and NGC 3077 taken with the newly configured AP155 platform.

🔭 Project Summary

Target: M81 (Bode’s Galaxy), M82 (Cigar Galaxy), and NGC 3077

Capture Date: April 11, 2026

Constellation: Ursa Major • Distance: ≈ 11.5–12.5 million light-years

Type: Spiral Galaxy (M81) + Starburst Galaxy (M82) + Disturbed Companion Galaxy (NGC 3077)

Imaging Period: April 11, 2026 • Total Integration: 4 h 36 m (LRGB + Ha)

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

Telescope: Astro-Physics 155mm Starfire EDFS f/5.3

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

Mount: iOptron Tri-Pier with column extension on custom steel pier

Processing: PixInsight & Photoshop

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

Field Includes: M81, M82, NGC 3077

Table of Contents Show (Click on lines to navigate)

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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

BXT BlurXTerminator by RC-Astro

CC Cosmetic Correction

CT Curves Transformation Process

DBE Dynamic Background Extraction Process

ET Exponential Transformation

HDRMT HDR MultiScale Transform

HDRC HDR Composition

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

Summary:

M81 / M82 / NGC 3077 HaLRGB Processing Flow

Sequential summary of the AP155 first-light workflow, organized around the actual dependency chain rather than parallel lanes.

1. Linear Setup

1. Blink / Cull Subs Review lights and reject weak or questionable frames

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2. WBPP Calibrate • register • integrate • autocrop • CosmeticCorrection enabled

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3. Load Master Images L • R • G • B • Ha

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4. Build Linear RGB ChannelCombination from R + G + B

Linear RGB Branch

5. Prepare Linear RGB DBE → SPCC → BXT → NXT

6. Split RGB into Components SXT creates starless RGB and saves RGB stars for later

Saved Star Branch

Saved RGB Stars Held aside for final recombination

2. Luminance Processing

7. Prepare Linear L DBE → BXT → NXT → SXT

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8. Stretch L STF → HT

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9. Refine L GAME masks → CT → HDRMT → LHE

3. H-alpha Processing for Red-Channel Enhancement

10. Prepare Ha DBE → BXT → SXT

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11. Stretch Ha STF → HT

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12. Build Ha Mask Use HT + DynamicPaintBrush for targeted application

4. RGB Processing and HaRGB Build

13. Process Starless RGB Stretch → masks → CT → HDRMT → ColorSaturation → NXT

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14. Inject Ha into Red PixelMath on masked red channel • 50/50 Ha/Red blend

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15. Build Starless HaRGB Recombine channels into the final starless HaRGB image

5. Final Assembly

16. Add L to HaRGB LRGBCombination to merge luminance structure with color

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17. Add Stars Back ScreenStars using the saved RGB stars

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18. Final Photoshop Polish Crop • tonal polish • color refinement • watermark • exports

Processing this Image

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

1. Blink

I screened all subs and cal frames with Blink.

L: 47 frames, some satellite trail, but no frames removed.

Red: 23 frames - 2 removed for tracking errors - some of the very early frames.

Green: 23 frames- 1 removed for tracking errors - one of the very early frames.

Blue: 23 frames, 0 removed

Ha: 24 frames - 3 removed for tracking issues - again, these were early frames.

Darks: All looked OK

Flats: All looked OK

Dark Flats: All looked OK

2. WBPP 2.9.1

All frames were loaded into WBPP:

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
I chose NOT to use Drizzle processing.
WBPP run in 44:22 - no errors

3. Load Master Images and Create Color Images

Load all master images and rename them.
- Master Ha -300-seconds
- Master LRGB-90-seconds
Using ChannelCombination, create the Master RGB color image

Master RGB 90-second image (click to enlarge)

4. Initial Processing of Linear L Data

Run DBE for the L linear image. Use subtraction for the correction method. Choose a sampling plan that avoids the main galaxies and bright stars. Enhance sampling points in areas with greater fall-off. (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.
Run the PSFImage script to measure star sizes. X = 1.96 Y= 1.81. 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 a third more than the measured star sizes. See the BXT Panel Snapshot below.
Run NXT V3; refer to the parameters in the snapshot below.
Run SXT - no need to save the L stars, as we will not be using them.

Before BXT

BXT Correct Only

BXT Full

After NXT V3

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

Master L Starless Image (click to enlarge)

5. Initial Processing of Linear Ha Data

Run DBE for the Ha linear image. Use subtraction for the correction method. Choose a sampling plan that avoids the main galaxies and bright stars. Enhance sampling points in areas with greater fall-off. (see below)
Run the PSFImage script to measure star sizes. X = 1.95, Y 1.83. This will influence the values used in BXT.
Run BXT Correct Only
Run Full BXT using the parameters in the screen snapshot below.
Run NXT V3; refer to the parameters in the snapshot below.
Run SXT - no need to save the Ha stars, as we will not be using them.

Before BXT

BXT Correct Only

BXT Full

After NXT V3

HA Before BXT, After BXT Fix Only, After BXT Full, After NXT V3

Master Ha Starless image (click to enlarge)

6. Process the RGB Masters

Run DBE using Subtractive correction
Select a background preview and run SPCC on the image
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 the PSFImage script to measure star sizes. X = 2.57 Y= 2.2. 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 a third more than the measured star sizes. See the BXT Panel Snapshot below.
Run NXT - see the params used in screenshot below
Run SXT and save Star images.

Master RGB 90-second before SPCC and the SPCC Panel (click to enlarge)

Before BXT

BXT Correct Only

Full BXT

After NXT V3

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

7. Go Nonlinear

Using the STF->HT Method, convert the linear L and Ha images to nonlinear. Remember that we did a LinearFit of the Ha to the L image, so use the STF when doing this.

Using the STF->HT Method, take the linear RGB image and make it nonlinear.
Using Seti Astro Star Stretch, take the RGB Star image and apply nonlinear stretching. Lately, I have been using three levels of star stretching and then deciding later which one works best in the image. Below you can see the various parameters used in three Star Stretch panels and the resulting 3-star images created. (See Panel snapshot below for parameters used).

8. Process the Nonlinear L Starless Image

Use GAME to create masks for the Large and Small galaxies
Use CT to darken the background sky a bit
With the Large Galaxy Mask applied, use HDRMT with 8 layers, and check “To Lightness” and “Lightness Mask.”
With the Small Galaxy Mask applied, use HDRMT with 6 layers, and check “To Lightness” and “Lightness Mask.”
With the Small Galaxy Mask applied, run LHE with a scale of 42, a contrast limit of 2.0, an amount of 0.6, and an 8-bit histogram. This is designed to enhance small-scale structures.

After LHE - Small Scale (click to enlarge)

9. Process the Nonlinear Ha Starless Image

Use CT to darken the outside and darken the core a bit.
Apply LHE with a scale of 64, a contrast limit of 2.0, an amount of 0.20, and an 8-bit histogram. This will enhance smaller structures.

10. Process the RGB Image

Let's create some masks that we will be using with this image:
- Using the ColourMask process, create a WarmMask with the params in the snapshot below.
  - Use CT to boost it.
  - Use Bill Blanshan’s Blur Script to smooth it
- Using Range_Selection with parameters of a Range from 0.05 to 0.52, Fuzziness of 0.12, and a smooth of 20
  - Use the Dynamic PaintBrush to clean up the mask.
Apply CT to adjust color and tone scale
Apply a second CT to boost color saturation even more
Using the Large Galaxy Mask, run HDRMT with levels=7 and “To Lightness” and “Lightness Mask” checked.
Using the Small Galaxy Mask, run HDRMT with levels=7 and “To Lightness” and “Lightness Mask” checked.
Apply CT with the Small Galaxy Mask
Apply CT with the Warm Mask
Using the Range Mask, apply the ColorSaturation Process to enhance blues and suppress purples.
Apply CT
Applt NXT ( see params below)
Remove subtle magenta tones
- Invert the Image
- Apply SCNR with green at 1.0
- Invert the image.

11. Combine the Red and Ha images, and Process

Extract the 3 layers from the nonlinear RGB image, and secure the starting red image for use.
The next step is to create a mask to apply to the Red image so that the Ha contribution only goes where we want it to.
- Make a copy of the Ha image.
- Use HT to drop out the background
- Use the Dynamic PaintBrush to remove small areas in the background
- This results in the Ha_Mask.
Apply the Mask to the extracted red image.
Set up PixelMath to blend the HA and Red image.s See the equation set up in PixelMath Below.
With the Ha_Mask applied to the Red image, I dragged the PixelMath bottom triangle onto the Red image. I tried different blend rates:
- 10% Ha - 90% Red
- 25% Ha - 75% Red
- 50% Ha - 50% Red
- I chose the 50/50 mix as having the best look.
I then used the ChannelCombination tool to create a new RGB image from the RHa image and the previously extracted Green and Blue images.
Adjust with CT
Now it’s time to fold in the L image using the LRGBCombination tool - see the tool panel snapshot below to see the parameters used.
The image is now ready for polishing. These days, I export the starless image into Photoshop.
- There, I use the Raw Camera Filter to adjust global curves and color mix
- I use the lasso with a 100-pixel feater, select each galaxy, and tweak with the clarifier, texture, and Color Mix tools
- The image is then imported back into PixInsight so I can add the stars.

The extracted Red, Green, and Blue Images. We will work with the Red image.

LHaRGB image. This is now ready for polishing in Photoshop.

12. Process and Add the Stars Back In

I used the ScreenStars Script ot create three images with the LHaRGB image and the three star soze variation images.
Using the ScreenStars Script, add stars back into our RGB starless image.

Example of the ScreenStars script used to fold the stars back in, creating the final image.

Here are the three resulting images seen side-by-side. I choose the last one with the larger stars. (Click to enlarge)

Stars now added - Image ready for Photoshop Polishing!

16. Export the Image to Photoshop for Polishing

Save the image as a TIFF 16-bit unsigned and move to Photoshop
Do a slight crop to trim some from the top and left edge.
Make final global adjustments with Clarify, Curves, and the Color Mixer - slight tweaks, really.
Added Watermarks

Export Clear, Watermarked, and Web-sized JPEGs.

The Final Image!

Back to M81/82 and NGC 3077 Project Page

Alternatively, you can use the back arrow to return to the B33.NGC 2024 main page, or you can use the menu at the top of the page to continue your navigation.

Thanks,

Pat

First Light on the AP155 Platform - M81/82 and NGC 3077: April 2026 Image Processing Walkthrough

🔭 Project Summary

Special Note

Abbreviations Used

Summary:

M81 / M82 / NGC 3077 HaLRGB Processing Flow

Processing this Image

1. Blink

2. WBPP 2.9.1

3. Load Master Images and Create Color Images

4. Initial Processing of Linear L Data

5. Initial Processing of Linear Ha Data

6. Process the RGB Masters

7. Go Nonlinear

8. Process the Nonlinear L Starless Image

9. Process the Nonlinear Ha Starless Image

10. Process the RGB Image

11. Combine the Red and Ha images, and Process

12. Process and Add the Stars Back In

16. Export the Image to Photoshop for Polishing

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