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  #21  
Old 16-09-2016, 04:57 AM
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Slawomir (Suavi)
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Quote:
Originally Posted by Andy01 View Post
Quietly sitting back, munching popcorn and enjoying the debate.

However, I might not be able to resist the urge to jump in soon - but for now, just gritting my teeth, sucking it in and holding back.... Breath in, breath out, breath in, breath out.

Ahhhh, much better
Contrary to popular belief, astrophotography, as well as playing chess and fishing, can increase heart rate for numerous reasons

But getting back to the main topic; since I started experimenting with tone masks using more or less JP Metsavanio's technique, my images definitely got better, even if I am yet to learn how to use tone masks skillfully in narrowband astrophotography.
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  #22  
Old 16-09-2016, 02:15 PM
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There are many techniques out there and I enjoy the variety in images.
With LRGB images the parameters are much tighter.

I do thoroughly agree with the notion of concentrating on getting the basics
right as the most important thing. When the data is acquired well then colour processing tends to be quite easy. The best images are often the ones you have done the least processing on. A bit like plastic surgery. Some people think they may get away with it but its a short look!

Greg.
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  #23  
Old 18-09-2016, 08:54 AM
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Mark - fyi - J-P Metsavainio has just released a comprehensively updated version of his world renowned tone-mapping technique - which details how to correctly add colours to stars in both RGB & NB version.

https://dl.dropboxusercontent.com/u/...Mapping_v2.pdf

I'm not going to respond to Peter's rather heavy handed remarks other than to say each to their own, but don't knock it until you've tried it

But imo Suavi nailed it here - "I think that experimenting with numerous processing tools and techniques, breaking boundaries and over-cooking astro images brings invaluable experience that is essential in personal growth as an amateur astro imager and it allows for acquiring in-depth understanding of how to skilfully process astro data."

Spot on If my growth as an imager has gained any recognition whatsoever, it is solely due to the many mistakes I have made whilst experimenting, and the honest feedback from the good folk here on IIS.

So Mark, back to the original question - there are a great many methods of star removal and replacement out there, best to just experiment and see what works well for you.

Andy

Last edited by Andy01; 18-09-2016 at 10:41 AM.
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  #24  
Old 18-09-2016, 10:46 AM
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Atmos (Colin)
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There is likely to be a similar way of doing it in PS as to what I do in PI. My workflow is basically to create a good star mask, masking pretty much every star in the image. Pretty much any of the manipulation I do on the RGB side has a star mask to as to protect them for later on.

As I have not yet taken actual RGB data purely for NB data, I've only created synthetic RGB from the NB, star sizes will be different. I just invert the star mask so as to protect everything other than the stars and then drop in the RGB stars into the NB image.

Sometimes I find myself needing a copy of the image just before replacing the stars. After ever time I add the RGB stars I'll invert the mask and apply it to the rest of the image. As they're both identical (in the background, not the stars) it helps protect the star edges where the star masks fall off from the star and onto the background. This is mostly because the synthetic RGB stars have a substantially different nebulosity colour. Sometimes takes a couple back and forth but I have found that is the easiest way with my workflow.
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  #25  
Old 18-09-2016, 12:06 PM
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Quote:
Originally Posted by Andy01 View Post
Mark - fyi - J-P Metsavainio has just released a comprehensively updated version of his world renowned tone-mapping technique - which details how to correctly add colours to stars in both RGB & NB version......

I'm not going to respond to Peter's rather heavy handed remarks other than to say each to their own, but don't knock it until you've tried it ........

Andy
Oh Pleeease.... The method is hardly "world renown" .....I'd reserve a technique, such David Malin's pre-photoshop unsharp masking for such a moniker

Applying differing and arbitrary scaling and gaussian distributions to the data...which this method is chokka-block full of....might give you some pretty pictures but is guaranteed not to reflect the Physics of what's going on in the object.
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  #26  
Old 18-09-2016, 02:51 PM
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Well that was an interesting post. Thanks for the thoughts everyone.

Mark
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  #27  
Old 18-09-2016, 04:45 PM
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Oh Pleeease.... The method is hardly "world renown"
Apologies for the Hijack Mark, but Peter - Seriously, come off your high horse. When a speaker from Finland is invited to regularly present his methods and techniques in the USA and Europe, maybe it's just me but I'd be calling that world renowned. ...And he's very generous with freely sharing said techniques as well.

Perhaps if everyone was as generous with freely sharing their techniques, folks like Mark, myself, and others would learn even faster.
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  #28  
Old 18-09-2016, 05:15 PM
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...might give you some pretty pictures but is guaranteed not to reflect the Physics of what's going on in the object.
Well, right there is one subject ("Science vs Art") up for panel debate during the Siding Spring open Day "Science in the Pub" on the 30th Sept at the Coonabarabran Bowling Club. http://www.starfest.org.au/science-in-the-pub/

Fred Watson is the MC and David Malin is on the Panel.

Ive had a whisper that its pretty much a set up to provide a bit of an entertaining windup by the pretty-pic camp on DM, given hes previously made it fairly obvious what he thinks of NB uber-art .

Apparently it will be streamed live, ill try and get more info on that.
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  #29  
Old 18-09-2016, 10:56 PM
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Well, right there is one subject ("Science vs Art") up for panel debate during the Siding Spring open Day...
Good call Fred. I'd love to be there!

By its very nature any image processing will distort the representation of an object being imaged....and this I have no problem with so long as the spatial and chromatic relationships are preserved reasonably well. As David Malin says: the image still "respects the light". If a subtle feature is being enhanced, you are still showing something that is real...just normally harder to see. ( It's hard to argue against using filters, like reading glasses, to better see the world)

But what do we make of arbitrary adjustments that do everything but that? "Art" would be one description, hey... and if that floats your boat...go right ahead.

I simply choose not to. I find nature is remarkable enough, without the urge to Photoshop Uluru to look green at sunset
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