Features of interpolations algorithms for resizing

[ewa-splatting]

First, thanks for adding more well-proofed interpolation kernels into XnView.
Practical Question:
Are the new interpolations only used in resizing or are they also used in all other affine transformations like rotation ...?

Background Questions:
What kernel sizes for the higher interpolation is XnView using? I suspect from first tests that you did not choose very big kernels. I love to have kernels smaller than 4x4 since they are faster and since the infamous, degrading Gibbs rings are still quite small.

What is the prefiltering in the interpolation for enlarging and what is it for shrinking images? I do not see any aliasing when shrinking images, so there must be filters in the interpolation. Does it degrade the quality so much?

[helmut]

...
Practical Question:
Are the new interpolations only used in resizing or are they also used in all other affine transformations like rotation ...?

I'm just guessing here:
The interpolation methods/algorithms used in the resize dialog are only applied when resizing and not used for other operations like rotating. (Otherwise the choice for the algorithm would have gone to the options).

Background Questions:
What kernel sizes for the higher interpolation is XnView using?
...

I have no clue, Pierre's the one who knows...