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x6gas

M35 my first processing with PixInsight

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For the past couple of weeks I've been using the trial version of PI to see if I can get on with it; coming back to the hobby after a few years PI seems much more established and the results being posted on here look good so I thought I'd give it a go.

I was pleased to find that - for me - it wasn't too daunting to get to grips with, especially with the excellent tutorials posted by SGL members Harry Page and Barry Wilson (thanks guys!).  Now there is clearly a lot to learn as there are a lot of user defined parameters but I think that's inevitable with a flexible and capable piece of software.  After much fettling (and this did take me a long time to get to grips with) I've found the calibration and stacking to work really well and, while I am still exploring, I find the PhotometricColorCalibration process to be really useful.

Anyway, I've been playing with M35 RGB data to keep things nice and simple and I thought some members, perhaps those considering trying out PI, might be interested in the comparisons below.

The data is 300s subs of R x 20, G x 21, and B x 19 so 5 hours with bias, flats and darks.

Here's my original using my old workflow (registered using Registar, stacked in AstroArt 5, colour combination, stretching, and other processing in PS).

1039555057_M35LRGBcombinereduxtweakcolourcorrected1200px.png.48aaa81ee6eca60fe6c92a698261ed7c.png

And here is a version which was calibrated, stacked, combined and colour corrected in PI, but stretched and with star colours boosted in PS, with a small Gaussian blur applied.

1567129409_M35RGBPCCPIandPS1200px.png.cf166525f67b9c03d5bd1431333bf02d.png

And finally this is version done entirely in PI, stretched with just one application of the arcsinh stretch function and smoothed with a blur using the convolution routine.

80509756_RGBPCCarcsignstretch1convolution1200px.png.8670827b3ecff9331c4630823e8ca909.png

I think I like the star colour in the PI processed image - it is certainly seems easier to get strong star colour without introducing a lot of noise.  I have to say that, once you know your way around, PI seems much quicker to use and it appears that - on this simple RGB image at least - I can do everything in one programme and get a result I really like.

This is enough for me to decide that I will be purchasing a full licence of PI and I must confess that I am quite looking forward to finding out what more it can do.

Hope this is helpful.  Clear skies, Ian

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Very interesting post Ian. It is the eternal question: what is the best way to process? Your PI result has the best star colour, even if it appears perhaps almost a little ‘overcooked’ in some of the reddest stars? Good to hear that you are finding PI not as terrifying as rumours suggest! Good luck with your continuing PI journey. 

I am a fan of APP and PS for my processing, though am definitely not against PI. How do you fancy sharing your data set with me so that I can produce a version with APP & PS for comparison?!

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2 hours ago, PhotoGav said:

Very interesting post Ian. It is the eternal question: what is the best way to process? Your PI result has the best star colour, even if it appears perhaps almost a little ‘overcooked’ in some of the reddest stars? Good to hear that you are finding PI not as terrifying as rumours suggest! Good luck with your continuing PI journey.

Thanks for the reply Gav.

Personally I don't think there is a "best way" - just different and I can process data using my 'standard' workflow and then process it again making a minor change and the result can be really different!  Yes I wasn't sure what to make of the very red stars - especially the one to the right of the image.  I decided to leave it as it came out of PI in the interests of the comparison.  Interestingly they are there, very red, in the unstretched data but don't come out so strongly when I stretch the data in PS.

Very happy to share the data - I'll PM you.  

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Excellent Ian and I am so glad my new-ish tutorials are helping you gain confidence with PixInsight: it can only ever be a benefit to have processing options at your finger tips.

I have more tutorials planned, one in progress - it is simply down to time at the keyboard and all of the other competing demands on one's time.

CS!

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2 hours ago, Barry-Wilson said:

Excellent Ian and I am so glad my new-ish tutorials are helping you gain confidence with PixInsight: it can only ever be a benefit to have processing options at your finger tips.

I have more tutorials planned, one in progress - it is simply down to time at the keyboard and all of the other competing demands on one's time.

CS!

Well your tutorials are very thorough, Barry, and are incredibly helpful - nice to have text tutorials too as I can follow along without annoying the wife too much!  I can guess how long it takes you to put these together so very many thanks and I look forward to future ones.  I installed PI with some trepidation but thanks to the tutorials it has been a genuinely interesting and enjoyable learning experience.

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Well... thank you Ian for uploading all the files. I've had a quick fiddle with it all in APP and PS and here's the resulting image. It's certainly different to the three processes above! Not as much blue colour, or red for that matter. Better or worse? I don't think that's a relevant question. It's just different. Amazing what different software and the hands that use it end up making of identical data. So, what is the correct way to process an image?!!? Does that exist?

M35-RGB-11-Flat.thumb.png.91a1db4e10fe7c78b40908e178378492.png

 

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Very nice Gav.  As you say, different again - and I like yours too.  You've stretched it harder than I did and as you say the balance between the blue and red stars is very different...

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Good stuff Ian. Interesting to see the differences. Anyway, I do like this cluster, with the older and more distant bonus cluster NGC 2158 next to the main cluster. Good luck with your return to imaging and I look forward to seeing more images from you, whatever you use to process them!

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A fascinating thread, there is certainly no right and wrong way, I’m no expert but if you don’t mind sharing the data I can have a go with APP and Startools, the viewers would have another option to compare it with. 

Nebulae  or galaxies are usually used for these type of comparisons for processing tools, but maybe that’s because there is more of a convention of what these objects ‘should’ look like, even though they don’t look like that directly, being too faint to register any colour.

Good luck with your future imaging, I returned after a 25 year break and am enjoying it immensely.

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