How do people handle stars in their images? - Forums

Topic starter

Jan 20, 2022 · Edited: Jan 20, 2022

Just looking for some more guidance. The way I am handling stars at the moment is:

* Having done all the linear stuff, I stretch the NBRGB image to the level where the stars look slightly dimmer than I want them in the end
* I then use Starnet to separate any galaxy/nebula from the stars
* I work on the feinter stuff and stretch it to bring out the detail
* I may use deconvoltion on the stars that Starnet separated out before using Pixelmath to add them back in to the stretched starless nebula/galaxy
* I will then export to Photoshop where I may use curves to slightly darken the background and bring out the nebulosity/stars

I'm new to this, so was just looking for some tips.

Roger Nichol

Jan 20, 2022 · Edited: Jan 20, 2022

For nebulae, I remove them with Starnet++ from within Pixinsight (running on each R, G, B channel separately for an OSC image), clean up the residual artefacts and big stars using CloneTool, then replace them with a stack shot using the L-Pro filter - usually 30 to 60x 30s exposures. I find Photoshop most convenient for adding them back in in Screen mode, but it can also be done directly in Pixinsight using Pixelmath with an equivalent screen mode combination.

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Danny Lee

Jan 20, 2022 · Edited: Jan 20, 2022

Similar to Roger's approach.

I do my liner processing then stretch and remove the stars using StarXterminator in PixInsight. Sometimes I'll run EZ star reduction to reduce their size prior to extraction. Results vary but sometimes StarXterminator does a better job if I reduce first. Then I spend a good amount of time tidying up any dodgy bits left over.

I've now started shooting a stack of 30 second subs just with a UV/IR cut filter to try and get some natural star colour, I then process those to taste and add them back to the nebula image at the end using screen blend mode in PhotoShop.

I've used PixelMath in PixInsight in the past but it always seems to mess with my colours and brightness.

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Jeffbax Velocicaptor

IOTD Staff

Jan 20, 2022 · Edited: Jan 20, 2022

Hi.

At my step of learning (and I still have to learn a lot), I have personnaly stopped removing the stars except for some very specific hard stretching like for very faint IFN.

I prefer using several and progressive masks with photoshop, dividing my streching process into 5 to 8 steps. Not easy to detail here.

I find it more natural with no AI and I have a better control on the halos. I keep the halos as a signature of the scope. Don't know why.

Just my personnal way of doing it.

CS
JF
EDIT : talking about LRVB. Narrowband is different.

fewayne

Jan 20, 2022

Do processing in Astro Pixel processor, up through gradient removal and enough stretch to pick out the nebulosity
Export to Tiff, run starnet++ on the result, throw away everything but the original and the starless image
Pull both into Photoshop as layers. Set top one's blending mode to "difference". Use Stamp Visible to create a new bitmap layer of just the stars. Squirrel that away.
Do various enhancements in PS on starless layer, including exporting to Topaz Denoise AI for light noise reduction and re-importing result.
Place star layer on top of the stack. Set its blend mode to "Maximum". Stamp Visible to produce image with stars.

Probably wouldn't hurt to run starnet++ on a more-linear image; I've occasionally had issues with it crapping out when I give it one that's completely unstretched. Also, Topaz likes to be run as early as you can, I should experiment with that.

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Jason Cropper

Jan 20, 2022

Up until last week I used StarXTerminator and Photoshop 2022 only (dabbling in Pixinsight occassionally). I use Astro Pixel Processor to stack all my images. As of last week, Astro Pixel Processor has a built in star reducer and star removal tool. It does a spectacular job of star reducing and removal of stars. First time I used APP's star reducer was on this image: https://www.astrobin.com/okhnmh/

Now, my workflow usually goes like this:

1: Stack in APP
2: APP light pollution removal tool
3: APP star reducer (if needed)
4: Photoshop levels and stretch up until stars look best
5: StarXTerminator
6: Create star field image using 'Apply image/subtract' of the image in step 4 from the layer created in step 5.
7: Possible additional levels and stretch of starless layer
8: Process starless image in Photoshop
9: Process starfield image in Photoshop
10: Save and upload to Astrobin!

-jason

Clear Skies everyone!

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