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 ?
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