Interpolation options in Registeration

Software Siril
1

Hi,

What are the image quality implications for changing the interpolation options in the Register or SeqApplyReg commands:

The interpolation method can be specified with the -interp= keyword followed by one of the methods in the list { no[ne] | ne[arest] | cu[bic] | la[nczos4] | li[near] | ar[ea] }. If none is passed, the transformation is forced to shift and a pixel-wise shift is applied to each image without any interpolation.

I stack thousands of short exposures, so performance is important also, but I’m curious how much is to be gained in playing with more sophisticated interpolations. My FWHM is typically large due to my long focal length (1125-1500mm with FWHM of 3-5 typically) so perhaps pixel shifting is fine, but I thought I would ask.

2

Lanczos4 is the new default, from what I’ve seen it improves FWHM in the results by 8%. The problem is that it creates artefacts around stars, special care had to be taken for it and this results in rotations more than two times slower. Writing images to disk is in general slower though.
The previous default was area, which is safe and fast, the only downside being the slight loss of FWHM.