Quote:
Originally Posted by gregbradley
Sharpening is best achieved at the point of acquisition with good seeing, good focusing, adjustments for temperature for the focus.
Then in processing by removing subexposures with FWHM that is too large or star bloats from a passing thin cloud etc.
Sharpening also works best on images with strong signal to noise ratio so long enough exposure comes into it.
I find deconvolution is handy sometimes when the red or blue subs are bloated compared to the other colours and can get rid of unwanted blue or red rings around stars.
Multi scale decon can work if only in the bright areas of an image. Worms appear first in the weak signal areas of an image. So selective sharpening works best. High Pass filtering is fairly non destructive when masked in only on the detail areas.
Other than that I haven't found too much that works well for sharpening. It easily goes south and poor sharpening is the mark of an amateur.
Greg.
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Hi Greg & Mike,
I guess it's a matter of whether you want to show the full resolution picture
or a cut down small size version?
If you show full size after heavy sharpening then the worms will appear.
However there are many types of sharpening -
I like the one in Photoshop and the "smart sharpen" function.
I also have Fitswork4 which has:
Gaussian sharpening,
Iterative Gaussian sharpening,
Iterative PSF sharpening &
Deconvolution.
I find a mask is useful so that only areas of high signal strength are sharpened
otherwise the background will turn into blotches or worms
as per the example I have in the OP.
I have had interesting results using 3 x Drizzle in Deep Sky Stacker
on a small section of the picture.
That can bring out more detail when viewed at high resolution.
I don't think you can make everyone happy.
Sometimes I think that posters here need two pics full size -
one sharpened and one not?
cheers
Allan