[SciPy-Dev] Splines

denis denis-bz-py@t-online...
Wed Mar 13 13:54:03 CDT 2013

Charles R Harris <charlesr.harris <at> gmail.com> writes:

> I'm not sure you are interpreting 'prefilter' correctly. I haven't looked at
the scipy code, but the uniform spline coefficients can be gotten by filtering
forward and back along each axis. It essentially factors the fit matrix into
lower/upper factors with constant diagonals modulo boundary conditions, and
forward/reverse substitution reduces to IIR filtering. This is also used for
other interpolation schemes, for instance variance preserving interpolation
which is useful when matching scenes using mutual information.Chuck

  is "prefilter=True will filter out high frequencies in the data"
not correct ?  It's a pure preprocessing step,
spline_filter in ndimage/interpolation.py
iterates spline_filter1d Bspline smoothing along each axis.

How about running some testfunctions with / without prefilter,
do you know of any real or realistic ?

  -- denis

More information about the SciPy-Dev mailing list