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PixInsight => Image Processing Challenges => Topic started by: dhb2206 on 2019 February 11 09:40:40

Title: M42 and M43 Additional Process? #2
Post by: dhb2206 on 2019 February 11 09:40:40
Hmm, first post seems to have developed a fault - probably my attempt at adding a JPEG to it, so I'll give it a slot in dropbox (https://www.dropbox.com/s/mo8b9q25gg4eux3/2019-02-10-101.jpg?dl=0).

As winter is upon us in the northern hemisphere Orion is a decent target. I've been building subs for a couple of months (i.e. about 4 nights as the weather hasn't been playing ball), all with a 300mm lens attached to a Canon DSLR riding on a Skywatcher Star Tracker. There are 282 1 minute light subs at F5.6 and ISO 1600 making up the integrated image, no darks, no flats and no bias. I'd guess about 25% of these are really good quality. Anyway, I've gotten to the end of a post processing run from a drizzled integration of a square 3500 x 3500 preview and would appreciate any tips on where I may have digressed or whether there is more that could be done to improve the image.

My run consisted of:

DBE - default sample generation at a tolerance of 2, samples shunted to avoid stars and deleted where there is obvious nebulosity, reined back to 0.85 for normalised subtraction
MLT (Multiscale Linear Transform) for noise on layers 1 to 4 - 3 iterations at 0.5 application and thresholds: 4, 3, 2 and 1 masked by an inverse of a lightness abstract with applied STF stretch
Morphological Transformation - Erosion of 1 on a 7 structure applied to a star mask generated from the lightness mask
Histogram Transform on highlights to even out blown out R, G and B values (following a masked stretch and pink stars!)
Masked stretch on default values with a background preview active
MLT for noise stepped back on thresholds to 3, 2, 1, 0.5 masked by lightness extract auto clipped for shadows and highlights
ACDNR on defaults
Histogram Transform to reset black point with minimal clipping
Curves Transform - tiny tweak of RGB for contrast and a reasonable saturation increase
HDRMT (HDR Multiscale Transform) at 9 layers to lightness on a mask revealing just the core of M42

I'm pretty chuffed with the result though the jpeg doesn't do it justice (if I can get it to attach).....

I've stuck the files in a dropbox in case anyone fancies a play, but be aware, the files are large (575MB each)!

Base drizzle image is here: https://www.dropbox.com/s/vrcamdn8pqjwyn3/190210%20Drizzle.zip?dl=0
Post processed image is here: https://www.dropbox.com/s/kfdhzzhoqd9m54s/190210%20Drizzle%20Post%20Plus.zip?dl=0
Title: Re: M42 and M43 Additional Process? #2
Post by: Alejandro Tombolini on 2019 May 12 18:26:39
Hi dhb2206, congrats for your image!

I made a try with the integrated image you shared and you can find the processing steps here (http://pixinsight.com.ar/en/info/processing-examples/50/m42.html).

Regarding your steps you can perform BackgroundNeutralization at the same time that you do PhotometricColorCalibration
For saturated stars (pink stars), if you have the chance would be good to have shorter exposures times and perform and HDR composition. 

Saludos, Alejandro.
Title: Re: M42 and M43 Additional Process? #2
Post by: wimvb on 2019 May 14 10:21:17
Thanks for the process walk through, Alejandro. Great addition to your resources web site.
Title: Re: M42 and M43 Additional Process? #2
Post by: dhb2206 on 2019 June 30 06:51:01
Thanks Alejandro, been off-piste for a while. I'll give that a bash!