Quote:
Originally Posted by tornado33
I suspect a lot of astro imagers employ some sort of star size reduction in their processing.
Mainly in rich starfields it helps. In shots with my 10 inch scope especially in less dense starfields it may not be needed.
Scott
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Quote:
Originally Posted by Alchemy
i found the minimum filter tends to introduce halos even with extending and feathering, particularly in Nebs.
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Yes, I've used it a few times.
M52 is an example. I wanted to ensure the open cluster maintained good star colour.
Tip re: the minimum filter; If your halos are severe, you selection is to large or feathering too much. If follow the routine provided by Scott, don't stop at step 4. I extend this by a few additional steps, these are;
- If required Expand or Contract selection to cover star and slight edge of star
- Feather to taste (if you've got halos you may need feather by quite a few pixels
- Filter | Blur | Radial Blur - around 40 usually does the trick
You can do this on a separate layer, then blend it in with a selection mask in screen mode. That way you can alter the opacity and colour saturation purely on the stars and not impact anything else. This still calls for some trial and error. With time you'll gain more experience with what works best.
I will acknowledge that the minimum filter is rather nasty. I don't use it often. If you want to get your stars tight and colourful, deconvolution, followed by a strong DDP stretch and saturation boost works well. This is one of my preferred routines. Blend this layer in as soft light in PS (mask if desired). Make sure your DDP stretch is hard i.e. on the verge of being white clipped - this is important as the PS soft light blend is actually a darkening function, hence will alter your overall image histogram if not careful. If you don't do a hard DDP stretch you can still layer it on top of the original, but at an opacity of around 50%, then flatten and relayer again to get the same affect.
