TheSkySearchers

With Galaxy Season almost on us I thought that a Galaxy AP Challenge would be appropriate. Get us all into the Galaxy frame of mind.

So this month we have data kindly submitted by @Juno16 - thanks Jim!

This is OSC with a twist because Jim has provided us with standard OSC data file and then with a corresponding file of OSC captured with his L-eNhance filter. This give the option of extracting the Ha data from the L-enhance and adding it into the standard OSC. Jim did just that and his result can be found here viewtopic.php?f=66&t=18179&p=151546&hilit=m101#p151546

I've save the data as Jims original Xisf and also 32b fit and 16b tiff so everyone should be able to open a file. Get it here https://1drv.ms/u/s!Alj6NhuYfZtW2R2gzKL ... P?e=0Umlh4

The data will solve in PCC at FL 571mm and pixel size 3.76micron.

NOTE: If you want to add the Ha you'll need to register the images against each other - if anyone is not sure how to do that let me know and Ill provide you registered versions.

So Download what files you want and process in your software(s) of choice then post in this thread. The purpose of the APP Challenge is to share techniques so we can all learn and grow in our abilities so please describe your process steps and any special tricks you used to get your result. If you have been finding something difficult to do with this data - tell us and hopefully someone will be able to help.

Please consider submitting some data of your own for future challenges. Just send me PM and I'll take it from there.

Enjoy the challenge - I'm looking forward to having a go at this one.

David

So here is my attempt at @Juno16 Jims data. Thanks Jim!

M101 is much harder to do well than one would think. Thats from my own personal experience but I've seen lots of other imagers say the same. I'm not sure why - It has lots in its favour, size, location, details within the galaxy but I just struggle to do it well. This one is no exception - and its nothing to do with the data which is great.

I think its really useful to have some processing goals before you start a specific image otherwise its easy to meander along wherever the software decides to take you. So on this one my goals were; get some blue in the galaxy but without it being a deep blue (personal preference), incorporate Jims L-enhance data but shoot for magenta rather than deep red Ha (personal preference again), since we have RGB data get a nice range of star colour, get structure within the galaxy as far into the core as possible (accepting some noise in expense for detail), get some of the outer star clouds to show.

Processing was quite long winded and I took a few dead ends and had to backtrack several times to get what I wanted

In Pixinsight
Linear
Registered the two images RGB and LE (L-enhance) and cropped each maintaining reg,
DBE on RGB - I was seeing an axial gradient so did an axial pass then a normal pass which seemed to work well
DBE on LE
Colour correction - I tried PCC on RGB but it was not doing a good job - really washing out the colour that was there - I processed the PCC output in parallel to the non-PCC but in the end scrapped it as rather insipid.
Deconvolution, EZ-denoise and StarXterminator on both RGB and LE
Gently stretched starless files using HT

Non Linear
RGB - CT for contrast and saturation, LHE
LE - further tweaks in CT and LHE then I made a range mask and brightened up only the inner Ha areas - this may have been a mistake. Removed R channel and called Ha.
I tried several ways to get the Ha into the RGB (used NBRGB script, tried putting it in as a Lum layer - neither gave a good result and I think this is where I paid for my range mask mistake) but settled on blending it 50/50 (pixelmath) with the red channel from RGB and recombining as HaR-GB
HaRGB - further adjustments with CT and a gentle LHE
Stretched the RGB stars, increased the sat in CT then added the stars back to the starless HaRGB (Pixelmath).
I tried @STEVE333 's "make it pop" routine which usually gives me good results but this time was not very pleasing so not used.
Exported as 16b tiff

In Photoshop
Balanced background and adjusted black point (I find this much easier to do in PS)
Some minor tweaks on colour and sat in Camera raw filter
Tried my selective High Pass routine but like Steves "pop" it was not really giving a good result
Did a crop in and then exported both crop and uncropped as jpeg to give;
Its OK but honestly its not as good as it should be - the data is better than this. The Curse of M101 strikes again!!

Comments/suggestions on the process flow greatly appreciated

Excellent processing work David!

If I had to do it over, I would have submitted a target that isn’t such a difficult and subjective process.

I looked on Astrobin this morning and the differences between M101 images was immense. When I filtered the M101 images on Astrobin for highest “likes”, I found that the biggest difference between this data and Astrobin was resolution. Coloration was varied.

I really appreciate all of the time and work you spent on this data.
Seems like the data isn’t up there with the best images on Astrobin, but it’s okay. The problem (to me) is the direction that the processing software takes you (as you mentioned).
There are so many ways to go with this. I didn’t save the project in PI, but I did save many (about 15) “Final” versions. How’s that for not settling on a final!

I did find one process that was somewhat more subdued that the original that I submitted in original the post, but it looked pleasant to me, so I ran it through Topaz Denoise and it looks okay. Not a popping image, but more what I would think M101 would look like through a big dob in good skies. Of course, I really have no idea what that looks like!


Thanks for all of your hard work and great documentation David!

Truly one of the more difficult datasets I’ve produced and processed.

Juno16 wrote: ↑Thu Jan 20, 2022 4:23 pm Excellent processing work David!

If I had to do it over, I would have submitted a target that isn’t such a difficult and subjective process.

I looked on Astrobin this morning and the differences between M101 images was immense. When I filtered the M101 images on Astrobin for highest “likes”, I found that the biggest difference between this data and Astrobin was resolution. Coloration was varied.

I really appreciate all of the time and work you spent on this data.
Seems like the data isn’t up there with the best images on Astrobin, but it’s okay. The problem (to me) is the direction that the processing software takes you (as you mentioned).
There are so many ways to go with this. I didn’t save the project in PI, but I did save many (about 15) “Final” versions. How’s that for not settling on a final!

I did find one process that was somewhat more subdued that the original that I submitted in original the post, but it looked pleasant to me, so I ran it through Topaz Denoise and it looks okay. Not a popping image, but more what I would think M101 would look like through a big dob in good skies. Of course, I really have no idea what that looks like!





Thanks for all of your hard work and great documentation David!

Truly one of the more difficult datasets I’ve produced and processed.

Hi Jim, thanks for that.

I'll be passing round the begging bowl again quite soon so please throw some more data into it.

Yes there is a huge variance for M101 and honestly I dont think that your data was any more difficult than most - its just M101 seems to hate being processed! It kept dodging and weaving away from me making it very difficult to nail down.

I do like your last repro above. My difficulty is I can think an image is great then when i look at it two days later i think - "WHY DID I POST THAT!!!!"

Some nice processings already! I don't process RGB images anymore now that I've switched to NB imaging. So, this is a trip down memory lane.

I wasn't able to eliminate the axial background fluctuations with DBE, so, I needed to do more processing along the way to deal with it. I also noticed that my colors are different from the images above. Probably some error on my part.

LINEAR
Registered and cropped RGB and Ha (L-enhance R channel).
DBE on RGB image.
ABE on Ha image.
MultiscaleLinearTransform noise reduction on RGB and Ha images.
ColorCalibration on RGB image.

NON-LINEAR
HistogramTransformation to stretch RGB and Ha images.
Surface Blur Noise Reduction (a technique I posted some time back in the Image Processing sub forum) on both images.
Converted both images to starless using Starnet (create star mask checked for RGB image)
Combined starless images with NBRGBCombination
Noise reduction on NBRGB using TGVDenoise
Extracted Luminance from NBRGB
Sharpened Luminance using:

• MultiscaleLinearTransform

• LocalHistogramEqualization with Kernel = 26

• LocalHistogramEqualization with Kernel = 110

LRGBCombination applied to NBRGB with sharpened Luminance used as Luminance
Added STARS from RGB image
Final sharpening with UnsharpMask


Comments welcomed.

Steve

Hi @STEVE333

On the axial gradient, in DBE I placed 3 rings, each with, I think, 10 or 12 sample points and ran DBE, that pretty much cleaned up the axial gradient leaving a slight top to bottom linear gradient which was easily removed with a standard DBE.

I wonder if the difference in colour is coming from your use of NBRGB. I gave it a go here (I've never used it before this so was stabbing in the dark) but it was not coming out well at all. Would you have any tips on using that script and I may go back and have another try.

rgds

David

Jockinireland wrote: ↑Fri Jan 21, 2022 10:06 am Hi @STEVE333

On the axial gradient, in DBE I placed 3 rings, each with, I think, 10 or 12 sample points and ran DBE, that pretty much cleaned up the axial gradient leaving a slight top to bottom linear gradient which was easily removed with a standard DBE.

I wonder if the difference in colour is coming from your use of NBRGB. I gave it a go here (I've never used it before this so was stabbing in the dark) but it was not coming out well at all. Would you have any tips on using that script and I may go back and have another try.

rgds

David

Hi David. I tried running DBE with 3 rings but never could get rid of the axial gradients! I changed the positions of the three rings as well as the settings in DBE. Glad it worked for you, but, frustrated it wouldn't work for me. Some of the settings did make it better, but, when I ran a regular DBE to remove the top-to-bottom gradient the axial gradients got worse again!

I don't know much about the NBRGB. I think I only used it once before in 5 years of using PI. So, sorry to say I don't have any tips for you.

I like your version of this galaxy the best. Well done!

Steve

Here's my go at it. I think this is my first time processing someone else's data. I have submitted data in the past though.

I only processed the OSC file in PI.
1. DBE division
2. Histogram transformation
3. Background Neutralization
4. Color Saturation
5. TGVDenoise
6. Star Deemphasizer

Opened in Photoshop, cropped, Topaz noise reduction, converted to jpg.

I played with using the enhance combined with the RGB and wasn't happy with my results. So I went back and processed just the RGB in StarTools. ST lets you play with different combinations of color patterns and I liked the results of this one the best. I cropped it quite a bit just to see the detail.

I actually finished this image weeks ago, but I wanted to do a redo on the data because M101 is a really challenging object to process. Years ago, I did try processing some M101 data that I had taken, however I wasn't satisfied with the final results ... and the unfinished image will remain unfinished for the foreseeable future.

However, life does have a way a getting away from you, so I never did get around for a data redo ... so, here's my 3 week old processing attempt.

Processed 100% in Photoshop ...

Nothing fancy on this one ... just basic stretching (curves) ... background adjustment (Levels) ... tried some Tone Mapping, but I didn't like the results (Blended into image only 15%) ... tried some selective High Pass sharpening/contrast enhancement (with marginal results) ... did a Synthetic Background Replacement (however, it really didn't need it) ... the big surprise was the final color adjustment was done using Auto Color (this almost never works for me).

I can see how you would really like to get "more" out of a M101 image!

Thanks, Jim .... for posting your data.

Thats nice @Sky

I completely agree that M101 is really challenging to process. I dont know what that is but it just seems much harder than it should. I've captured it 3 times with different gear and I'm never really happy with the outcome.

@Jockinireland
@STEVE333
@AstroBee
@Gordon
@Sky

Thank you everyone for rolling up your sleeves and taking a punch at this tough one!

Like David said, I don't know why this target is so challenging to process. Even with that, the galaxy is very beautiful and I am sure that I will try it again!

Thanks again for everyone's work!

M101- Pinwheel Galaxy
**Processed with my own data.**
Here is the Pinwheel Galaxy from Bortle 8 in Toronto, Canada. Acquired with my ES127ED, guided SW EQ6R Pro, ASI 2600MC Pro, 72 x 240" frames stacked in DSS, processed in Photoshop. Notoriously elusive and difficult to process, just under 5hrs of sub exposures gave me some decent data, about half of which was had in average to poor seeing. Enjoy!

Hello Keester. A very nice processed image of M101 (Pinwheel Galaxy). An excellent core and sparkly spiral arms in your capture. Thanks for sharing this work with us on here Keester and a big welcome to the TSS forum.

Hi there i hope i put this image in right...so here it is the pinwheel galaxy i really enjoyed processing it..thanks




Rhoda