dealing with chromatic abberation

[waynef]

What would be a good workflow to deal with chromatic aberration from a refactor. Trying to work this out my gut tells m you will need to process the blue channel separately as it will require more deconvolutions and sharpening to get the same level of focus or rather sharpens as the other channels and then re combine, but I am not really sure what would be the best approach. How would this chance if you used a braader yellow long pass filter to try and reduce the chromatic aberrations?

[waynef]

Ok my apologies I only noticed this tutorial now.
http://forum.startools.org/viewtopic.php?f=7&t=254#p434
However I am still wondering if there is any merit in separating the blue channel and sharpening it a bit more aggressively since the blue color is not focusing properly on the ccd?

[admin]

Hi Wayne,

Sorry for the belated reply - I'm on limited keyboard time, battling RSI
You're definitely thinking along the right lines to counter chromatic aberration, strictly speaking deconvolution of the out-of-focus channel(s) should fix this type of CA. The only problem is that we're dealing with stars and that often star cores are overexposed. The overexposed pixels are clipped and constitute 'missing' data, which in turn makes deconvolution mathematically impossible (ringing artefacts will appear at the very least).

So this is why we can really only resort to less 'correct' 'hacks' in such a case.

[waynef]

I also read an article about his that implement a rescale of the color channels. http://hugin.sourceforge.net/tutorials/tca/en.shtml

Would it then not help to take some extra subs at a much shorter exposure to try and capture the information for the stars in a HDR way?Or am I missing something else here?

[admin]

I also read an article about his that implement a rescale of the color channels. http://hugin.sourceforge.net/tutorials/tca/en.shtml

Would it then not help to take some extra subs at a much shorter exposure to try and capture the information for the stars in a HDR way?Or am I missing something else here?

That may indeed mitigate the problem... If you ever give this a try I'd be interested to see the results!

[waynef]

I am currently working on getting a data set to try this with a new refactor. I will post the result in a week or twos time once I have enough integration to get reasonable results