From: Alan Friedman <alan@greatarrow.com>

Date: April 20, 2005 12:13:01 PM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Jupiter Sharpness Comparison

Nice images! Thanks for posting the interesting report.

Choosing the right amount of sharpening is a very challenging craft. It reminds of asking for directions on the subway and getting the response "just get of at the stop before me..." - by the time you're done you realize you should've stopped a while back. 

I don't see much difference in detail between the images - the increased crispness seems to be at the expense of increased granulation? But I am also very sensitive to over sharpening because I am a prime offender.

My technique usually produces a number of streams for luminance (4-8 or so) which I process separately and then restack for the final image. I sharpen these preliminary stacks for detail just past the optimum point - slightly grainy - and allow the final stacking  to average and lessen the noise. This is of course a very tedious process in Keith's Image Stacker. I need to make the time to learn how to accomplish the same techniques in ASTRO IIDC - my first attempts with the beta did not work out right. The images were not aligned correctly - perhaps because it drifted too much during the capture?

Alan

On Apr 20, 2005, at 1:44 PM, milton_aupperle wrote:

Hi folks;

I had very  good stable skies last night as the jet stream shifted way

north of me into the North West Territories and Arctic. So I managed

to get some good shots of Jupiter (with GSR) and Luna last night -

accumulating another 9 gigabytes of 16 bit video movies.

Since I finally had some decent shots of Jupiter to work with, I ran

the same movie through Astro IIDC for stacking and alignment, and then

varied the pre sharpness amount in each run from none to extreme.

Astro IIDC has the ability to sharpen each frame before stacking and

aligning them - which in theory should help accentuate subtle features

as long as the CCD gain noise isn't too high.

You can read about it and see the (subtle) difference that it makes in

the Jup_Comp_050419.jpg file in the Planetary folder. The 16 bit tiff

is a little bit easier to see the subtle differences too.

One thing I'm now more convinced of now is that 16 bit planetary

imaging does make a difference for very subtle features. However to

take advantage of it you need very good seeing conditions (and have to

stay in 16 processing from start to finnish) - otherwise

it may not be worth the money.

TTYL..

Milton J. Aupperle

President

ASC - Aupperle Services and Contracting

Mac Software (Drivers, Components and Application) Specialist

#1005 - 815 14th Avenue. S.W.

Calgary Alberta Canada T2R0N5

1-(403)-229-9456

milton@outcastsoft.com

www.outcastsoft.com

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