PixInsight Forum (historical)

PixInsight => Wish List => Topic started by: Niall Saunders on 2010 January 29 07:06:08

Title: Image Integration Process - Setting Sigma Clipping sliders
Post by: Niall Saunders on 2010 January 29 07:06:08
Juan,

When using, for example Winsorized Sigma Clipping, I wonder whether it would be more convenient to be able to set a slider such that a 'desired number' or 'desired percentage' of pixels eventually end up in the High/Low clip images.

It is not necessarily intuitive to decide 'where' to set the Sigma sliders to.

Sure, I was able to tweak the 'High Sigma' slider the other day, such that I totally eliminated a whole bunch of cosmic ray strikes from my integrated master dark - and these strikes were totally invisible in the source darks, and were also invisible when Sigma High was set too low.

Would it not be possible to set a desired 'amount in the dustbin' level, and to then have PixInsight (iteratively) work out the required Sigma multiplier needed to achieve this?

Further,

Can you give us a brief explanation of what the ADU values observed in the Clipping Images actually represent?

I felt, last night, that these were not just simply '0.000' or '1.000', where '1' represented a pixel that 'had been' clipped, from 'at least' one of the source images.

Does the ADU value represent a 'counter', for example, which increments for every image in the dataset that had that particular pixel fall into the 'outlier' category, and thus required to be 'clipped'?

Cheers,
Title: Re: Image Integration Process - Setting Sigma Clipping sliders
Post by: mmirot on 2010 January 29 10:21:55
I think the process consul gives a number of rejected pixels( %?) for each Image as integrates .
 I don't have much detail on how to interpret the output.

( I would be nice if someone could post a few notes. Perhaps an annotated screen shoot. I am not sure the difference of SNR and SNR steps too )

However, looking at the high low rejection map is still the best way.

Max