ICEINSPACE
Moon Phase
CURRENT MOON
Waxing Gibbous 71.5%
|
|
13-09-2016, 06:05 PM
|
|
Registered User
|
|
Join Date: Jul 2006
Location: Sunshine Coast
Posts: 1,827
|
|
Relacing narrow band stars with RGB stars.
Hi,
Could someone please tell me how to replace narrow band stars with RGB stars. I have tried this a few times but always end up with dark circles around the RGB stars.
Thanks.
Mark.
|
13-09-2016, 06:18 PM
|
|
PI cult recruiter
|
|
Join Date: Apr 2010
Location: Brisbane
Posts: 10,584
|
|
What software are you using, Mark? I can give advice on how to do it in PixInsight but that may not be much help to you...
|
13-09-2016, 07:46 PM
|
|
Registered User
|
|
Join Date: Jul 2006
Location: Sunshine Coast
Posts: 1,827
|
|
Hi Rick. I am using Photoshop CC.
|
13-09-2016, 09:01 PM
|
|
PI cult recruiter
|
|
Join Date: Apr 2010
Location: Brisbane
Posts: 10,584
|
|
Quote:
Originally Posted by batema
Hi Rick. I am using Photoshop CC.
|
Sorry, Mark. Hopefully somebody who groks PS can help.
|
13-09-2016, 10:02 PM
|
|
Registered User
|
|
Join Date: Jul 2006
Location: Sunshine Coast
Posts: 1,827
|
|
No worries. Thanks Rick. I keep saying I should buy PixInsight.
|
13-09-2016, 11:31 PM
|
|
My God it's full of stars
|
|
Join Date: Mar 2012
Location: Melbourne
Posts: 3,259
|
|
Try using Straton or Annies Astro Actions to remove the NB stars with one click.
Basically using JP Metsavanio's tone mapping method but faster. http://www.skypixels.at/downloads/ade/Tone_Mapping.pdf
Then layer up your pre-aligned RGB stars in lighten or screen blend mode.
|
14-09-2016, 06:11 PM
|
|
Registered User
|
|
Join Date: Jul 2006
Location: Sunshine Coast
Posts: 1,827
|
|
Thank you Andy.
|
14-09-2016, 10:41 PM
|
|
Galaxy hitchhiking guide
|
|
Join Date: Dec 2007
Location: The Shire
Posts: 8,136
|
|
Quote:
Originally Posted by Andy01
Try using Straton or Annies Astro Actions to remove the NB stars with one click.
Basically using JP Metsavanio's tone mapping method but faster. http://www.skypixels.at/downloads/ade/Tone_Mapping.pdf
Then layer up your pre-aligned RGB stars in lighten or screen blend mode.
|
Have to say I am appalled by this "tone mapping" technique.
The process distorts the real colours of objects and puts colour into places where it becomes meaningless.
Might as well get the airbrush tool and paint in some colours because they look nice....sorry...simply don't see the point.
|
15-09-2016, 06:29 AM
|
|
Registered User
|
|
Join Date: Jul 2006
Location: Sunshine Coast
Posts: 1,827
|
|
What method would you use Peter? Can you point me in a direction?
Mark
|
15-09-2016, 09:16 AM
|
|
PI cult recruiter
|
|
Join Date: Apr 2010
Location: Brisbane
Posts: 10,584
|
|
Quote:
Originally Posted by Peter Ward
Have to say I am appalled by this "tone mapping" technique.
The process distorts the real colours of objects and puts colour into places where it becomes meaningless.
Might as well get the airbrush tool and paint in some colours because they look nice....sorry...simply don't see the point.
|
What's your objection, Peter? You're perfectly entitled to be appalled. Just wondering why. Applying a stronger stretch and heavy noise reduction to the weaker components of a narrowband image is common practice. Otherwise the majority of Hubble palette images would be solid green.
Cheers,
Rick.
|
15-09-2016, 10:01 AM
|
|
Galaxy hitchhiking guide
|
|
Join Date: Dec 2007
Location: The Shire
Posts: 8,136
|
|
Quote:
Originally Posted by batema
What method would you use Peter? Can you point me in a direction?
Mark
|
Fair 'nuff. I'd also use Pixinsight....but if you must use Photoshop...Assuming you've registered the images, I'd suggest a layered mask of the RGB stars, feather the edge to suit (about 1.5-3.5 pixels) and place the layer on top of the NB stars. You might need to do this a couple of times at different feather levels to remove any dark rings.
|
15-09-2016, 10:12 AM
|
|
Galaxy hitchhiking guide
|
|
Join Date: Dec 2007
Location: The Shire
Posts: 8,136
|
|
Quote:
Originally Posted by RickS
What's your objection, Peter? You're perfectly entitled to be appalled. Just wondering why. Applying a stronger stretch and heavy noise reduction to the weaker components of a narrowband image is common practice. Otherwise the majority of Hubble palette images would be solid green.
Cheers,
Rick.
|
I thought I was pretty clear on why...but no matter....to re-iterate, the extreme noise reduction and extreme stretch artificially blurs and extends all fine-structure (and real) details and replaces them with a fuzzy mess....in short you get colour in places where there is none and lose it in places where it should be prominent. The only real fix for lack of signal is more exposure.
Suffice to say, this is not the technique I used when I submitted this H-alpha blended image to "The malins"
|
15-09-2016, 10:46 AM
|
|
PI cult recruiter
|
|
Join Date: Apr 2010
Location: Brisbane
Posts: 10,584
|
|
Quote:
Originally Posted by Peter Ward
I thought I was pretty clear on why...but no matter....to re-iterate, the extreme noise reduction and extreme stretch artificially blurs and extends all fine-structure (and real) details and replaces them with a fuzzy mess....in short you get colour in places where there is none and lose it in places where it should be prominent. The only real fix for lack of signal is more exposure.
|
OK, so it's just another technique that can produce appalling results when misused/overused. I can certainly understand and agree with that
|
15-09-2016, 03:59 PM
|
|
Galaxy hitchhiking guide
|
|
Join Date: Dec 2007
Location: The Shire
Posts: 8,136
|
|
Quote:
Originally Posted by RickS
OK, so it's just another technique that can produce appalling results when misused/overused. I can certainly understand and agree with that
|
Don't mind me Ric....just a peeve of mine.
There are so many sow-ear images out there that some try to turn into silk-purses by means of star shrink/CA removal/motion blur/noise removal/unsharp mask/decon/etc./etc. ...rather than stepping back and looking critically at their raw data.
Good data on the other hand simply doesn't need much post-processing to give an image that "Wow!" factor IMHO.
|
15-09-2016, 05:24 PM
|
|
Registered User
|
|
Join Date: Sep 2014
Location: North Queensland
Posts: 3,240
|
|
On the other hand, 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. I reckon it would be quite a challenge to find an amateur astro imager who have never clipped a histogram or destroyed good data with noise reduction. Besides, everyone is at a different stage in their journey and have different circumstances, so acquiring good data may not always be possible.
Just my two cents.
|
15-09-2016, 06:48 PM
|
|
Galaxy hitchhiking guide
|
|
Join Date: Dec 2007
Location: The Shire
Posts: 8,136
|
|
Quote:
Originally Posted by Slawomir
On the other hand, 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. I reckon it would be quite a challenge to find an amateur astro imager who have never clipped a histogram or destroyed good data with noise reduction. Besides, everyone is at a different stage in their journey and have different circumstances, so acquiring good data may not always be possible.
Just my two cents.
|
Nah.....I'm thinking you've put the cart before the horse.
You wouldn't try to palm off a photo-shoot of a bride on her wedding day by taking out of focus .jpg images, with motion blur and the wrong colour temp...then hope like hell there is a Photoshop filter to fix the mess. (You'd also probably get sued )
Also, you don't need a $100k rig to get good data. There are simply some basics you have to get right first up.
In focus? If not re-check and shoot again!
Stars round ? If not check polar alignment, tracking, auto-guiding parameters, mechanicals until they are.
Image noise? Insufficient exposure time/ bad calibration frames. Maybe both. More telescope time and nail your reduction data prior to image calibration.
Only then should you fuss with the smoke and mirrors of post-processing...
that's my 5 cents worth
|
15-09-2016, 07:02 PM
|
|
Registered User
|
|
Join Date: Sep 2014
Location: North Queensland
Posts: 3,240
|
|
I was mainly referring to this comment:
Quote:
Originally Posted by Peter Ward
Have to say I am appalled by this "tone mapping" technique.
The process distorts the real colours of objects and puts colour into places where it becomes meaningless.
Might as well get the airbrush tool and paint in some colours because they look nice....sorry...simply don't see the point.
|
As for data quality, most of us here seems to struggle with getting the mechanicals spot on (mainly because of using a mass-production but affordable mount), thus data is often substandard and hence the search for processing tools that help to at least somehow hide imperfections in the data.
Just my 10 cents
|
15-09-2016, 08:06 PM
|
|
Galaxy hitchhiking guide
|
|
Join Date: Dec 2007
Location: The Shire
Posts: 8,136
|
|
Quote:
Originally Posted by Slawomir
I was mainly referring to this comment:
As for data quality, most of us here seems to struggle with getting the mechanicals spot on (mainly because of using a mass-production but affordable mount), thus data is often substandard and hence the search for processing tools that help to at least somehow hide imperfections in the data.
Just my 10 cents
|
I'll see your 10 cents are raise you twenty
I agree...but suspect many astro-imagers are simply using a focal length that is simply too terse for the rest of gear they are using.
Good deep sky data at 3 metres (or more) FL is hard to get!....even for top shelf gear (mainly due seeing)....but there are many sublime images in the 500mm to 1100mm that simply didn't need a gold standard in tracking ability....just a critical eye and attention to details.
Nail the focus, nail the tracking/guiding and go deep when you have mastered them....but not before, as GIGO applies (Garbage IN, Garbage Out)
Only then should you fuss over the software to best show-off your solid foundation work.
|
15-09-2016, 08:35 PM
|
|
Registered User
|
|
Join Date: Sep 2014
Location: North Queensland
Posts: 3,240
|
|
Quote:
Originally Posted by Peter Ward
I'll see your 10 cents are raise you twenty
I agree...but suspect many astro-imagers are simply using a focal length that is simply too terse for the rest of gear they are using.
|
I totally agree. Not sure where this quite common amongst deep space imagers big scope on EQ6 trend originates from...I'm honestly struggling to consistently get quality data at 570mm and 1.33" per pixel with my AZ-EQ6...
Quote:
Originally Posted by Peter Ward
....but there are many sublime images in the 500mm to 1100mm....
|
Thank you Peter!
|
15-09-2016, 11:02 PM
|
|
My God it's full of stars
|
|
Join Date: Mar 2012
Location: Melbourne
Posts: 3,259
|
|
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
|
Posting Rules
|
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
HTML code is Off
|
|
|
All times are GMT +10. The time is now 11:18 PM.
|
|