ISIS rejection function when adding images

[Robin Leadbeater]

Can anyone tell me what the rejection function does when adding a sequence of images ("Tools", "image processing 2")

ISIS_addition_rejection.png (6.46 KiB) Viewed 2946 times

Thanks
Robin

[Christian Buil]

It is the parameter of a sigma-clipping algorithm for reject deviant values during addition process (for very noisy data, in normal work, do not slect the option). Adjust by successive trial.

Christian

[Robin Leadbeater]

Hi Christian,

Just checking that I understand this correctly.

The function looks at the distribution of values in all the exposures for each pixel position and rejects any outliers at each position. (This would for example eliminate cosmic ray hits)

similar to the IRIS sigma clipping function for example
http://www.astrosurf.com/buil/iris/tuto ... 121_us.htm

Is this correct?

Is this function different from the cosmic ray filter in the general tab ?

Thanks
Robin