DDP star bloat

Image processing, astrometry, photometry, etc.
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Morten Lerager
Posts: 69
Joined: 08 Oct 2021, 14:53
Location: Denmark

DDP star bloat

Post by Morten Lerager » 06 Feb 2023, 14:04

Hi'
How can i prevent star from bloat.
If I have a stack in a 16bit fits with stars up to 55-60000 they
become greater than 16 bit after a DDP.
When saved to 16bit most of the stars are 65535.
The only way I know to do this, is by carefull curve raising. ( not so good )
Or using "Normalised Tone Stretch" in Affinity Photo.
How do i approach this in AstroArt 8.

Regards Morten Lerager.
HEQ5 Pro 150PDS 60mm guide. Asiair.
Asi294mc. AA8.

fabdev
Posts: 478
Joined: 03 Dec 2018, 21:43

Re: DDP star bloat

Post by fabdev » 08 Feb 2023, 22:35

Hi, it's not easy to reply without seeing the actual image. By the way, you could use the StarNet plugin to apply DDP only on the nebula and not on the stars:

1) Duplicate the image, let's call it "B".
2) Apply your DDP on image "A".
3) Apply a DDP with low gamma and mid white point to image "B" (so that stars are not bloated)
4) Remove stars in "A" with Starnet plugin.
5) Duplicate "B" let's call it "C".
6) Remove stars in "B" with Starnet plugin.
7) Subtract from "C" the image "B" to create a stars image.
8) Add to "A" the stars from "C".

Greetings, Fabio.

User avatar
Morten Lerager
Posts: 69
Joined: 08 Oct 2021, 14:53
Location: Denmark

Re: DDP star bloat

Post by Morten Lerager » 09 Feb 2023, 19:35

Hi Fabio.
I was hoping for some solution with stretch without clip.
I already use starnet for narrowband nebula and merge the stars from broadband.
Thank you.
HEQ5 Pro 150PDS 60mm guide. Asiair.
Asi294mc. AA8.

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