Thank you for kind words, Mathew, David, Adam, JA, Fred and Marc!
Quote:
Originally Posted by Bassnut
Thats excellent Igor, especially for urban skies!.
Ive used a Continuum filter in the past for star removal and it works (in this case very well!), but these days starexterminator is way easier, no need for extra exposure time.
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The problem with algorithmic removal of stars (no matter neural networks or masks) is that while they work well for bright stars, they produce some artifact in border-condition stars and don't work for extremely faint barely-distinguishable background stars(which are a million times more).
The physical stars removal by subtraction of a continuum frame has the advantage that while giving some unwanted artifacts on bright stars,
it works good on medium, works well on weak and perfectly on an extremely faint indistinguishable "porridge" of background stars.
As a result, you get not only the removal of stars, but a much flatter, less noisy background, although you didn't even realize that part of its "noise" were groups of super weak indistinguishable stars barely leaked through the narrowband filter. Another bonus is that after retouching of artifacts, you can substract that starless H-alpha from the continuum image and this give you nearly perfect stars mask for future post-processing operations.
The closer an object is to the Milky Way, the stronger this effect is.
(It is a pity that there is a limitation, the method is suitable only for emission nebulae, in other cases there is no alternative to neural networks or masks-based wizardry.)