Re: Mode Combine in AIJ ?

Posted by sengle01 on Dec 21, 2017; 7:48pm
URL: http://astroimagej.170.s1.nabble.com/Mode-Combine-in-AIJ-tp917p943.html

Karen,

I'm sorry, I completely missed this reply when it first arrive and just saw it now.

It's a good point - my quick, short answer would be that I have no real preference.

The most common application that I personally see for the mode combine is producing sky flats. Unless you're unlucky, observe densely packed regions of space, or simply aren't taking enough exposures, the sky values should be the most represented.

Perhaps, if you were combining some images and a star fell on the same pixels in 10 out of 20 images, then you might get 10 star values and 10 sky values, so two peaks. In this case, I would expect the star peak to be narrow and the sky peak to be broader. In that case, is there any way to (relatively easily) look at the neighboring values for each peak, and choose the broadest of the peaks?

Best,

Scott

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From: karenacollins [via AstroImageJ] <ml+[hidden email]>
Sent: Monday, December 4, 2017 7:10:50 AM
To: Scott Engle
Subject: Re: Mode Combine in AIJ ?

 

Scott,
I looked into adding a "mode" combine option to DP. However, it is not clear to me which value to choose if there are two more values with the same number of occurrences (i.e. the distribution is multi-modal). Do you have a preference on how that case is handled?
Karen

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