Beginning to understand. Regarding Panorama convolution kernel as implemented in avisynth, are you saying that it should be discarded because you cannot implement b-spline interpolation with a finite convolution kernel or that if it looks better, let it be. Is the alternate method fundamentally correct, should it be renamed ( to Cubic64Resize...).
Am I right in thinking that the difference between the b-spline (infinite support) and the Panorama method (finite support) is "those boundary conditions".
MfA, if it makes sense to implement it , can you help to understand the Unser algo for a "true" spline interpolation? Is it this one? (p 7) bigwww.epfl.ch/publications/thevenaz0002.pdf
May be , I will get more luck with
http://www.cs.sunysb.edu/~mueller/pa...s98_Design.pdf
In Appendix, coefficients with the optimal interpolation that is C2 and 4EF (6 filter weights).