[Scipy-tickets] [SciPy] #515: ndimage.zoom introduces artefacts at right and bottom edges
SciPy
scipy-tickets@scipy....
Wed Oct 17 19:42:36 CDT 2007
#515: ndimage.zoom introduces artefacts at right and bottom edges
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Reporter: 0ion9 | Owner: stefan
Type: defect | Status: assigned
Priority: normal | Milestone: 0.7
Component: scipy.ndimage | Version: devel
Severity: normal | Resolution:
Keywords: ndimage, data, representation, spline |
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Comment (by stefan):
Another point: why can't mirror extension work? Remember that we can
interpolate a value inside our data, i.e. any coordinate from 0 to L-1,
where L is the length of the array. If we extend by reflection, we have
coefficients:
0, 1, 2, 1, 0
We can interpolate anywhere between (0,1),(1,2),(2,1),(1,0). But if we
extend by mirroring, we have
0, 1, 2, 2, 1, 0
We cannot interpolate between (2,2) -- that spline fit is never done. To
do that, the interpolation algorithm will have to be modified to *first*
extend the series, then do a spline fit, etc. (Currently, interpolation
requires no extension before fitting splines).
--
Ticket URL: <http://scipy.org/scipy/scipy/ticket/515#comment:3>
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