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Description: There were several things bothering me about the original version of this, not the least of which was the mottled appearance of the IFN from over stretching and over noise reducing it. I have only 12 hours and the IFN is exceptionally faint, so I tried to respect that more in this iteration.

I am also going through fits and starts with learning to use Pixinsight more, so I was working through a new flow from Rogello Bernal Andreo's book, "Mastering Pixinsight" using this data.

This is a "ground up" reprocess utilizing more PI than ever before, (for me), but after too much time in the deep end, I did swim back to my happy place in PS to finish up.

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Description: Softened some areas that felt over-contrasted to me and some minor touchup.

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H

Title: Complete Reintegration and Reprocess

Description: This reprocess was a saga for me!

First of all, because I am relying on weighting, rather than culling, subs during integration, this reprocess used 19 hours 58 minutes of total integration.

Galaxies can be challenge to process because their bright cores can overwhelm fainter detail.

To date I have been using Layers, Masks and different stretches in Photoshop to blend the reduced-brightness cores back into the image.

This reprocess is my first substantial foray into HDRMT. I used masks on each of the two galaxies and then FAFOed with HDRMT to get a good result. HDRMT is a great tool, but definitely a bit of a black box where lever flipping and slider sliding is your friend.

I also used BlurX with the Beta v2 AI since I was having some issues with reddish stars becoming pink/purple while applying BlurX. See this PI discussion here: https://pixinsight.com/forum/index.php?threads/blurxterminator-ai2-beta.20019/

I also experimented with using 1x CFA Drizzle Integration, as recommended by the Pixinsight developers for OSC data. I had far less than good results with that when compared to the regular VNG Debayer integration. (I still need to experiment with the separate channel processing too, which can help with chromatic aberration in stars. I don't have a lot of this, but I do have a little, even with my reflector and reducer/coma corrector.)

My results with CFA Drizzle yielded a much greener image at the STF (unlinked) stage. After DBE and SPCC, the CFA Drizzle image yielded some stars that had faint pink halos that were amplified dramatically by even the lowest level of BlurX.

I tried CFA Drizzle with NSG and a semi-manual calibration/integration process at both .7 and 1.0 Drop Shrink with similar results. I also did a completely WBPP with Local Normalization integration with CFA Drizzle at 1.0 Drop Shrink, and results were essentially the same.

By no means am I recommending that others not use 1x CFA Drizzle per PI Developer recommendation but, given my results with this experiment, I will only employ it if I experience issues similar to what they describe in the literature: (scroll down...) https://pixinsight.com/doc/docs/SPCC/SPCC.html

I welcome any insights as to why I was getting bad results with the 1x CFA Drizzle Integration.

Side note for newbs like me...CFA Drizzle uses your debayered images as references only, (essentially), and then uses data compiled in the processing of the debayered images into the drizzle files to finally integrate your calibrated (only) data into color data. It does not re-integrate your debayered images using some kind of drizzle magic. I was kinda stuck on how this works for a while and it didn't seem like anyone on the interwebs was being clear enough for me to get through my thick skull. It's in there now!

Throughout this processing, I used masks generated with the GAME Script. This is a great tool and you should have it in your arsenal...Google it.

I utilized the masks to minimize some posterization effects caused by using BlurX on a bright galaxy core on a Macintosh, (this is a thing apparently), to prevent overcooking some detail with Unsharp Mask, and to increase saturation on brighter images while keeping the background more neutral. Masks in PI are pretty clunky when compared to Photoshop, but still usable for me now that I've got my head around them.

On this image I only used Photoshop for some final refinements. I find the PS Camera Raw tool's Color Noise reduction to be really helpful as a final touch, and other tools in Camera Raw help to polish things nicely.

And, as usual, I did my best with the dust in the foreground.

Another shout-out to Adam Block's tutorials. I just upgraded to the "Horizons" courses because they get into some more detailed applications and I am finding that I need that on occasion. My head was spinning watching and re-watching his videos as I was processing this. His advice was especially helpful on HDRMT and a bit on Drizzling.

I think my processing has been pretty solid on this image and that the limiting factor is data quality, not that better processing couldn't be done by someone with better processing skills. I guess that's a good place be with processing.

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J

Title: Applied Russell Croman's Color Corrected HDRMT process

Description: As I mentioned in the previous version description, this has been my first foray into using HDRMT. I really like the detail this brought out, but it was lacking in color in the HDRMTed main galaxies. This was made clear by some folks who "called me out" at the Pixinsight for Beginners Facebook Page, which is so embarrassing! Doesn't everyone only want to "go live" with a perfect image? https://www.facebook.com/groups/418182585405588/posts/1295044244386080/?comment_id=1295509381006233&reply_comment_id=1295582617665576&notif_id=1673376896729878&notif_t=group_comment&ref=notif

So, upon further research, I found an Adam Block tutorial that pointed to a process that was outlined by none other than @Russell Croman in this post on the Pixinsight Forum https://pixinsight.com/forum/index.php?threads/color-corrected-hdrmt.15769/ .

Basically, by combining the hue and saturation HSI channels extracted before using HDRMT with the intensity channel extracted after HDRMT, you'll wind up preserving the color. Read his post at the Pixinsight Forum.

I had also lost some galaxies doing a second badly executed star reduction late in the processing of the last iteration, and I made a few other minor improvements. Also embarrassing.

My brain hurts from learning so much over the past few days...

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K

Description: Slightly darkened, selective color saturation on the galaxies to bring out Ha and OIII regions.

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Title: Preserving color while enhancing dynamic range

Description: It's been cloudy and/or Moon-y here, which has given me the opportunity to work on improving some PI skills and experimenting with different techniques.

As I have mentioned before, I am working on using the tools in Pixinsight to enhance dynamic range on bright galaxy cores, (most prevalent example), while not losing the hue and saturation/color.

Sometimes this requires using the technique mentioned above that Russell Croman posted about, remove Hue and Saturation channels (HSI Channel Extraction), apply HDRMT, remove Intensity (also HSI Channel Extraction), Combine HS, with after HDRMT I to adjust bright galaxy core but keep color.

On this image, the core of M82 wasn't bright enough to warrant that leading to the core of M82 being over-saturated. Lesson here is that this is a great technique, if warranted by a bright enough galaxy core.

Another lesson learned was the application of Generalized Hyperbolic Stretch to keep the cores more under control earlier, rather than just applying a stretch from Histogram Transformation. GHS is an interesting tool to me in that it is a "shortcut" of stuff I used to try to do with Curves in Photoshop.

I applied Saturation while masking the background, (a luminance mask), before stretching as well. This helped to give me more color to lose while stretching and seems to have worked well.

Another thing of note. I am pretty sure, (I would need to do more experiments to be sure), that applying SCNR green before using BlurXTerminator led to some color problems with the galaxy cores. My early process is DBE-SPCC-Mask brightest cores to prevent posterization-BlurX-SCNR...

This image was presenting some chromatic aberration issues with stars that I again addressed with targeted application of Color Saturation and then some subtle Convolution. I think from here on out I am going to use Separate RGB integration in WBPP to help mitigate any CA.

This image is challenging because of the huge difference in brightnesses between the galaxy cores and the IFN/Galactic Cirrus. The two galaxies themselves present unique challenges as well, requiring different processing tools to get a good result. That then requires careful application to get a balanced representation of the two. It has been a big learning curve reprocessing this while trying different tools and strategies.

The only thing I used Photoshop for on this processing is some Color Noise Reduction and a very slight saturation reduction.

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M

Title: 1x Drizzled OSC experiment

Description: This data is some of the most challenging I have shot. The drastic brightness difference between the galaxies and the galactic cirrus that I want to draw out presents various challenges. I should probably add another 20 hours to the integration which would probably help out with some noise issues. I keep revisiting it as a practice tool because of those challenges.

With this iteration I had started out wanting to finally understand the reasons for using 1x drizzle on OSC data.

I revisited the drizzled integration had run several months ago, (and not used), and tried to objectively see the difference in the color output from the un-drizzled data. When compared to the examples on the SPCC document information written by Juan Conejero with Pixinsight, I could definitely see the differences. When comparing undrizzled and drizzled results after DBE and SPCC are applied, with some saturation to show the problem, it's obvious that the undrizzled data has lost some Ha and OIII, and the general cast of the galaxies are a yellowish green. I had been using SCNR to address the green, but it really didn't leave a natural color representation but the drizzled integration did. I ended up doing a lot of futzing with Color Saturation of specific color to bring out the nebulae/colors in the galaxies with the previous iterations. This time I only masked the galaxies and increased saturation uniformly. It's difficult for me to describe the issue, but you can read about it here, and check your own results for comparison: (Scroll to section 7.2) https://pixinsight.com/doc/docs/SPCC/SPCC.html

I also spent a bunch of time with @Adam Block's "Stretch Academy" honing some techniques with GHS. GHS is a really great tool that does things I've been sorta trying to do with curves since my "early days" with Photoshop, but much more easily and with better results. I highly recommend that you check out Adam's "Stretch Academy" which is part of his "Fundamentals" courses. He does a far more complete job explaining the various stretching tools and histogram altering tools than anyone else I've watched.

I did "cheat" and use Photoshop for some final noise reduction in a few spots. I really like Russell Croman's NoiseXTerminator, but it doesn't handle color noise as well as the Camera Raw filter Noise Reduction and Color Noise Reduction in PS, and sometimes Layers are just easier than masks in PI for dialing in a few things.

I did sacrifice some of the cirrus in order to get a slightly less noisy image with this iteration, As I mentioned, I really think I need more time on this to really draw out the cirrus.

I hadn't started out to create a new revision on this image, but rather to learn some new stuff. However, I think this version is my best so far, (and I did learn a lot of new things!)

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N

Description: Increased contrast and some saturation in galaxy cores, slightly brightened cirrus, more NoiseXTerminator and SCNR green.

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