Pre processing in Nebulosity

Questions and answers about processing in StarTools and how to accomplish certain tasks.

Pre processing in Nebulosity

Postby brasspoodle » Mon May 08, 2017 11:54 am

I'm sure this is a question that has been asked many times before but wonder what I should or shouldn't be doing in Nebulosity before working on the .fit file in StarTools. Currnetly I use a Canon DSLR to capture the images in RAW format (CR2 files). I then calliabrate (darks, flats, bias removed), normalize intensities, debayer, align and stack. At this point Nebulosity prompts you to save the .fit file, which then becomes the file I use in StarTools. If this is correct then when StarTools asks me what kind of image I'm using what should I answer: 1st option "Linear, was not bayered...", 2nd Option "Linear, was bayered..." or whatever the 3rd option is?

I'm still getting my head around this so might all be rather obvious. Managed to unquarantine StarTools on my Mac so that was already a big adventure for someone not overly familiar with Terminal commands...
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Re: Pre processing in Nebulosity

Postby admin » Sat May 13, 2017 4:09 am

Hi,

The first option is meant for data that has already been white-balanced, which is usually the case (though it is not preferred) when using DSS. This dialog is so that StarTools knows how much the data has been modified since being acquired by your sensor.

In general, StarTools can achieve better results the more "virgin" the data is; using non-white balanced data may yield marginally better results in terms of noise reduction.

Hope this helps!
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Re: Pre processing in Nebulosity

Postby brasspoodle » Sat May 13, 2017 8:40 am

Thanks Ivo. I gather then that I should be checking he second option as I'm using a modded 40D for image acquisition and don't think there is any auto white balancing in Nebulosity. Really just wondered what class of image would result if the Demosaic (debayering) option was applied. Option 2 seems to work anyway :-) Thanks for the reply.
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