Sigma Clipping / Linear fit clipping : how to get the right values ?

[Philippe B.]

Dear all
There are many topics on ImageIntegration process, but I would like to know how you determine the values clipping low and hight ! There are some default values, for sure, but how to improve quality ? Is smaller values are better ? Why clip high is lower than clip low

Sorry for this question, ImageIntegration/calibration are the most powerfull process (my 1rst result is amazing compare to other software like DSS) but I would like to understand all the function. For sure I use the tutorial from Vincent !!!!

Thanks for you reply
Best
Philippe 

[mmirot]

I believe less number is more rejection.

I find the best thing to do is find a stack with hot pixels and airplane trails etc.

Then evalute the rejection maps untill the settings do just enough to get 96-99% of the hot stuff removed.

I generally do a lot less to low pixel rejection.  It is a lot harder to see whats happening. I don't want to clip it

Max

[Harry page]

Hi

As said the smaller the sigma number the higher the rejection will be 

I am afraid it is a case of trial and error with the settings and looking at the rejection map

you only want to reject outliers ie hot / cold pixels , planes etc , so if you see too many pixels rejected you need to increase the sigma setting

if you look at the bottom of this page http://www.harrysastroshed.com/pixuser/intergration.html to see what I regard as a good map 

Finaly I do not use the rejection percentage as a guide as it could be anything from 3 % to 0.01 % 

Hope this helps

Harry

[Enzo De Bernardini]

Harry, I want to take this opportunity to thank you for the tutorials on you website, are a great help to learn many processes.

Best regards,

Enzo.

[Harry page]

Hi Enzo


I hope they helped to get you going 

Harry