fiddling with astro image data

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stuck
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fiddling with astro image data

Post by stuck »

In anticipation of Monday, which is a Public Hol here in the UK, being wet and windy I've downloaded the astro image data from this challenge on The Skysearchers:
https://theskysearchers.com/viewtopic.php?f=107&t=17126

However with it being too cold to be out in the garden this afternoon, I've been poking at the data already. This is my first attempt at turning it into an image.

Ken
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HansV
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Re: fiddling with astro image data

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Excellent! :thumbup:
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Hans

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Re: fiddling with astro image data

Post by stuck »

It could be better, the blue/green detail at about 2 o'clock is blown out. There's still plenty of rain forecast for Monday though so I ought to have time to fiddle some more.

You know what they say, nothing's right until version 3 :smile:

Ken

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Re: fiddling with astro image data

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I'll be looking forward to the result!
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Re: fiddling with astro image data

Post by Graeme »

That's brilliant Ken! You have the Bok's globules standing out really well. What software did you use to process the data? Did you map it to Sii-R, Ha=G, Oiii=B?

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Re: fiddling with astro image data

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Graeme wrote:
02 May 2021, 08:26
...What software did you use to process the data? Did you map it to Sii-R, Ha=G, Oiii=B?...
I converted the .fit files to TIFFs using the default settings in Fits Liberator. I then used an ancient version of Photoshop CS2 to get each image into a separate channel (because I've yet to figure out how to do that in Affinity Photo). Yes, the mapping was the 'Hubble palette', Sii-->red, Ha-->green and Oiii -->blue. I then opened the composite TIFF in Affinity Photo and started playing. One of the latest whizz bang feature of Photo v1.9 is a dedicated 'Astro remove background filter'. That was handy.

Version two is in the workshop already. This one involves moving away from the defaults in Fits Liberator and using an ArcSinh stretch. Using that seems to have retained the detail that's blown out in this first version.

I'll post again in due course.

Ken

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Re: fiddling with astro image data

Post by Graeme »

I downloaded the 90 day trial of Affinity but haven't used it much, the remove background filter would be useful for removing gradients caused by light pollution. PixInsight is popular amongst astrophotographyists.

Looking forward to version two.

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Re: fiddling with astro image data

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Graeme wrote:
02 May 2021, 17:39
PixInsight is...
about 5 times the cost of Affinity Photo :grin:

There's not enough red in v2 but I have recovered the blown out bits this time.

Ken
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Re: fiddling with astro image data

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Yes, there's more detail in the blue/green parts, but some of the red details are lost now. You win some, you lose some...
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Re: fiddling with astro image data

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That's toned down the saturated peaks nicely. The reduced red has flattened the image a bit overall. Some people map the Siii to blue as well as the Oii and the Ha to red to produce a dual narrow band image. It works because Siii is at the red end of the spectrum and Oii at the blue end.

So will you be posting your image on the Sky Searchers forum? :smile:

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Graeme

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Re: fiddling with astro image data

Post by PJ_in_FL »

Beautiful! Thanks for sharing.

When is the 3D image coming out? :smile:
PJ in (usually sunny) FL

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Re: fiddling with astro image data

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PJ_in_FL wrote:
03 May 2021, 16:19
When is the 3D image coming out?
It's been out for a while. This is what it looked like about 5200 years ago :grin:

Ken

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Re: fiddling with astro image data

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Here's version 3. Not sure it's right though.

Ken
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Re: fiddling with astro image data

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Each of the three has its pros and cons...
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Re: fiddling with astro image data

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Graeme wrote:
02 May 2021, 19:20
...will you be posting your image on the Sky Searchers forum?...
Just tried to do that but the thread is locked :sad:

Ken

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Re: fiddling with astro image data

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Regards,
Hans

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Re: fiddling with astro image data

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stuck wrote:
04 May 2021, 18:10
Here's version 3. Not sure it's right though.

Ken
There is no right and wrong really. The Hubble palette produces a false colour image. Tri band narrow data sets are collected with a mono camera and allocated to any part of the visible spectrum to make different aspects of the image stand out. Ha and Siii are both at the red end of the spectrum and the Oii is at the blue end but very faint. A colour camera would record a dull red image.

stuck wrote:
04 May 2021, 18:22
Graeme wrote:
02 May 2021, 19:20
...will you be posting your image on the Sky Searchers forum?...
Just tried to do that but the thread is locked :sad:

Ken

It was locked because it's not the current processing challenge. But now it's unlocked, just for you!

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Graeme

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Re: fiddling with astro image data

Post by stuck »

Graeme wrote:
05 May 2021, 05:28
...But now it's unlocked, just for you!..
:thankyou: Posted now, it's pending moderation.

Ken