Original Post - 12-28-2021:

Best subs from one night of data.  I used the NINA image exposure calculator as a test and made darks to match up with them.  This is why the exposure lengths are strange.  Probably going to stick with regular 30, 60, 90, etc, exposure levels in the future.

Update - 01-16-2023:

Reworked this data set as I was never happy with the first version and wanted to use new process software/modules on it. Fewer subs were filtered out during this revision.  I still need to add Ha subs for some hydrogen highlights in a future version.

I moved the BlurXTerminator step right after SPCC per recommendations for v1.1.1 and also used AI v2.  This is the first time I have enabled the mouseover function in Astrobin for the preview as I wanted people to see the cropped (zoomed) version without having to look for it.

Target Workflow (L,R,G,B subs):

ASIFitsView (Blink Equivalent)
- Review all subs and remove visually bad frames (none this time)

WBPP
- Cosmetic Correction Applied
- Pedestal added to avoid clipping in later processes = 800DN
- Set Local Normalization (Automatic)
- Check Image Integration
- Do not do Drizzle Integration as subs still to be weeded out in next step

Subframe Selector
- Sort by FWHM, PSF Signal Weight, and Star Count individually to weed out subs that stray far below median values

Drizzle Integration
- Use Normalization Files

Dynamic Crop
- Trimmed quite a bit as GT81 is not really built for galaxies and no use processing more data.

Linear Fit
- use Statistics to find the lowest channel Median value for reference sub = B

LRGB Combination
- Uncheck L channel and load R, G, B
- Uncheck Chrominance Noise Reduction

DBE - RGB and L separately
- Apply Subtraction with Tolerance 2.0, Smoothing Factor = 0.65

Image Solver Script
- Search and set target from database = NGC2403

Spectrophotometric Color Calibration
- White Ref = Average Spiral Galaxy
- QE Curve = Ideal QE Curve
- Set ZWO R, G, B filters
- Make very small background preview
- Set Background Neutralization->Region of Interest->From Preview->Select the background preview

BlurXTerminator - RGB and L separately
- Run PSFImage script and get average of the FWHMx and FWHMy values - RGB = 2.65, L = 2.94
- Turn off Auto PSF and set to corresponding numbers
- Sharpen Nonstellar = 0.7
- Check "Correct First" for RGB image

Bill Blanshan SCNR
- Amount = 0.60

NoiseXTerminator - RGB and L
- Turn on 24-bit STF lookup tables
- Apply with Defaults

StarXTerminator
- Check 'Generate Star Image' and 'Unscreen Stars' for RGB
- Remove stars from RGB image and save as RGB_Starless and RGB_Stars
- Remove stars from L image using default settings and save as L_Starless

Generalized Hyperbolic Stretch on RGB_Starless, RGB_Stars, and L_Starless
- Multiple iterations to zero in and finalize with Linear at end

Histogram Transformation on L_Starless
- Darken Background without clipping

LRGB Combination
Apply L_Starless to RGB_Starless

Extract CIE Luminance from RGB_Starless
- for use in later steps
- save as RGB_Starless_L

Curves Transformation
- Apply RGB_Starless_L as mask to RGB_Starless and protect background
- Adjust contrast and colors to taste
- Use Bill Blanshan cyan color mask to enhance blue of galaxy spiral

Exponential Transformation
- With RGB_Starless_L mask applied and background protected
- Apply with 0.5 amount

Curves Transformation
- Apply RGB_Starless_L as mask to RGB_Starless and protect background
- Adjust saturation
- Invert mask and adjust background saturation

Range Mask
- Limit to very center core of galaxy
- Apply to RGB_Starless with background protected
- Adjust colors (R,G) to bring out glow

Local Histogram Equalization
- Apply RGB_Starless_L as mask
- Large structures - KR = 150, CL = 1.3, Amount = 1.0, 12-bit
- Small structures - KR = 50, CL = 1.3, Amount = 1.0, 8-bit

Pixel Math to Re-add Stars
- Formula = ~((~RGB_Starless)*(~RGB_Stars))

Histogram Transformation
- Darken Background

NoiseXTerminator
- Denoise = 0.70, Detail = 0.30

Dynamic Crop
- Final Crop of the zoomed in version

Gimp
- Rescale the zoomed/cropped version to be same scale as the version 3 uncropped (for mouseover function in Astrobin)

Astrobin
- Upload zoomed/cropped version B
- Upload version 3 as final
- Set mouseover on final to be version B