Original post - 12-31-2021:

Quick shoot of my first star cluster with nebulosity.  Star masking could be better, but the star donuts do provide contrast to the nebulosity when in full screen view.  I decided I liked it this way and that I could do another version in the future if I ever care enough to come back to this data.  Otherwise, I feel like I need to adjust gain/exposure to tone down the star flaring and halos in a new data set before making another round of it.

This was the second target since I started using the new NINA advanced sequencer (highly recommended along with the plugin modules).

I also recently spent an evening tuning my focuser settings and adding offsets so I can shoot all filters one after another to average out the sky quality throughout the night.  Nice option since I was only shooting one night on this target.  Have backlash fully accounted for and getting awesome curves with 1.0 for R2 almost every time using L filter for all autofocus routines.

Update - 12-29-2022:

Coming back to this data with a year more experience and knowledge.  The first time I processed M45, I had little experience and no idea what the goal image should look like.  Needless to say, I cringe now at my previous attempts and finally decided to do this update.  I also dropped some of the lessor subs this time (around 40 fewer than the original integration)

One item of note is that the ASI1600MM Pro is susceptible to micro-lensing on very bright stars such as the ones here and Alnitak in the Horsehead Nebula.  I have taken some steps here to minimize the micro-lensing artifacts, though they are still showing.  The technique I used required merging of several masks and then clone stamp edits of the masks to limit adjustments to the affected areas.  The artifacts seemed most prevalent in the cyan mask.  Prob spent more time working on this than the rest of the processing combined.  New processes make this version way more compelling than my first attempt.

Latest process - 12-29-2022 (Pixinsight): 

Target Workflow:

Blink (I actually use ASIFitsView which is free and better IMO for this step)
- Review all subs and remove visually bad frames

WBPP
- w/ Interactive mode for Local Normalization
- Cosmetic Correction Applied
- Pedestal added to avoid clipping in later processes
- Drizzle Enabled
- Best Images reviewed and used to Generate Local Normalization Ref for each channel

Subframe Selector
- Sort by PSF Signal Weight and Star Count to weed out subs that are far from median values
- Note best reference image for each filter for use in Image Integration

Image Integration
- Use Normalization and Drizzle files

Drizzle Integration
- Use Normalization Files

Dynamic Crop

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

LRGB Combination
- Uncheck L channel and load R, G, B
- No Chrominance Noise Reduction

DBE
- combined RGB image

BlurXTerminator RGB and L images
- This target uses defaults
- PSF Image script and note average of FWHMx and FWHMy - RGB = 3.25, L = 5.94
- Uncheck Auto PSF and set value for each and Execute

Image Solver Script
- Search and set target from database for best result

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

Bill Blanshan SCNR
- Drag to image without modification

NoiseXTerminator
- Turn on 24-bit STF lookup tables
- Apply Defaults

StarXTerminator on RGB
- Check Generate Star Image
- Check Unscreen Stars
- Execute and save as RGB_Stars

StarXTerminator on L
- Reset to defaults
- Execute and save as L_Starless

Generalized Hyperbolic Stretch - RGB and L images
- Multiple iterations to zero in and finalize with Linear at end

Histogram Transformation on L
- Darken background

Curves Transformation
- Use L as mask
- Adjust contrast and colors to taste
LRGB Combination 
- Apply L_Starless as L to RGB_Starless

Exponential Transformation
- Apply L as mask to protect background
- Utilized defaults on first iteration, then Order = 0.5 on second iteration

Curves Transformation
- Adjust Saturation without masks

Pixel Math
- Re-add Stars using PixelMath = ~((~RGB_Starless)*(~RGB_Stars))

Histogram Transformation
- Darken Background by reducing head of curve up to clip point

Bill Blanshhan Star Reduction Method 3 Script
- Two iterations

Curves Transformation
- Special Range and Cyan combo mask with Clone Stamping to limit affected regions

NoiseXTerminator
- Turn on 24-bit STF lookup tables
- Denoise = 0.70, Detail = 0.30