From: Milton Aupperle <milton@outcastsoft.com>

Date: July 30, 2008 1:31:12 PM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Choosing the proper confidence level percentage


Hi Dave;


On 29-Jul-08, at 10:01 AM, doodlebun wrote:

  Jupiter imaging requires the proper setting of confidence levels or 

the result will be noisy and oversharped. I have created a set of 

confidence levels from the same movie taken under good seeing. As I 

seemed to prove to myself 50% is the way to go. Which percentage would 

you choose? look at:


http://web.mac.com/davidbleser/AncientDocuments/CONFIDENCE_LEVELS.html


The movie shows you certainly don't have much turbulence there at all. Most nights I get +/- 20 arc seconds of motion (half of Jupiter's disk) between frames when capturing at 30 frames per second.


Once you drop below about the 60% level in this movie,  your losing a lot of detail and winding up with a soft blurred image.


I would have reduced the "Sharpen Frames By" from "Medium" to "Very Light" and then used around 65 to 75% CI for stacking. Sharpening will accentuate noise.


And for the "Image Processing" Controls, I would reduce the amount of sharpening I'm doing at Rad 1.0 and probably Rad 1.5 levels too. The smaller the radius, the more noise levels gets accentuated.


Also, are you checking the movie stack log text file to see how many frames are actually being stacked (the last line in each Multiple Areas will be "Stacked xx out of yy frames"), right? You may have selected sat 60% confidence level, however the number of frames that are actually stacked depends on the matching tolerance. They may not be be the same number at all. Also in the log is the "Pixel Noise Percentage:" value which indicates the intraframe noise amounts. Basically it calculates the difference in each pixel value between each adjacent frame, which is basically a measurement of noise. The higher the gains, the higher the noise and the higher this number is.


Hope That Helps..


Milton J. Aupperle

President

ASC - Aupperle Services and Contracting

Mac Software (Drivers, Components and Application) Specialist

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