Help needed with M33 processing in PI

[CraigD1986]

Here's my first attempt at the Triangulum galaxy (M33) shot on 22nd September. I'm not particularly happy with this image and really struggled with the processing. This is exactly 3 hours of data (2 min subs) and stacked in DSS then processed in Pixinsight. I'm still on a trial version of PI so am a complete novice with it but I just couldn't extract any colour from the image without really boosting the saturation and therefore introducing loads of noise and gradient. I'm not sure where I'm going wrong with this.

I've also attached the DSS output for reference.

 

Skywatcher 72ED DS Pro
ZWO533MC Pro
Astronomic L3 filter
Star Adventurer
Guided via ASIAir Plus


Any advice is greatly appreciated. Thanks in advance. 

Autosave.tif

[wimvb]

Here's my attempt

 

• Dynamic Crop
• DBE
• Photometric Colour Calibration including background neutralisation
• Multiscale Median Transformation noise reduction och chrominance only (removes colour mottle)
• (cloned)
• arcsinh stretch
• star removal (M33_galaxy)
• contrast enhancement and colour saturation on M33_galaxy
• Histogram transformation on the cloned image (M33_stars)
• (cloned again)
• star removal on the second clone (M33_starless)
• combination of three images in PixInsight: M33_galaxy + M33_stars - M33_starless

 

I had to separate the image in its colour components and realign those components in order to remove the chromatic aberration and dispersion effects

Edited October 17, 2022 by wimvb

[ONIKKINEN]

Here is my try, with ASTAP, Siril and Photoshop:

First Binned 2x2 in ASTAP, then resampled a bit further to 80% in Siril as the stars are still a little bit big but i think binning 3x3 might be a bit too much. Then background extraction, Photometric colour calibration, Little bit of Asinh stretch to preserve colour for the subsequent stretches, SCNR green, Partial histogram transformation stretch and export to Photoshop.

In Photoshop created a starless layer with StarXterminator and subtracted that from the original to create a stars-only layer. Camera raw fringe tool for the stars-only layer to reduce chromatic aberration somewhat. Not sure what the best way to reduce CA in refractor images is since i dont image with one, but this one was simple and worked somewhat well for this purpose. Stretched the galaxy only layer further while leaving the stars as-is from the partial Siril stretches. Did some layer masked desaturation, denoise and sharpening to parts where applicable (denoise and desat for background, other way around for the galaxy). Recombined the stars with a simple screen function for the galaxy layer in front of the stars.

Now that i am looking at the image i am thinking maybe i left it a little bit too green, but i always get "colourblind" when processing and often change my mind the next day. But for testing the data it will do for now.