scipy.ndimage._interpolation:spline_filter

Parameters

input : array_like

The input array.

order : int, optional

The order of the spline, default is 3.

output : ndarray or dtype, optional

The array in which to place the output, or the dtype of the returned array. Default is numpy.float64.

mode : {'reflect', 'grid-mirror', 'constant', 'grid-constant', 'nearest', 'mirror', 'grid-wrap', 'wrap'}, optional

The mode parameter determines how the input array is extended beyond its boundaries. Default is 'mirror'. Behavior for each valid value is as follows (see additional plots and details on boundary modes <ndimage-interpolation-modes>):

'reflect' (d c b a | a b c d | d c b a)

The input is extended by reflecting about the edge of the last pixel. This mode is also sometimes referred to as half-sample symmetric.

'grid-mirror'

This is a synonym for 'reflect'.

'constant' (k k k k | a b c d | k k k k)

The input is extended by filling all values beyond the edge with the same constant value, defined by the cval parameter. No interpolation is performed beyond the edges of the input.

'grid-constant' (k k k k | a b c d | k k k k)

The input is extended by filling all values beyond the edge with the same constant value, defined by the cval parameter. Interpolation occurs for samples outside the input's extent as well.

'nearest' (a a a a | a b c d | d d d d)

The input is extended by replicating the last pixel.

'mirror' (d c b | a b c d | c b a)

The input is extended by reflecting about the center of the last pixel. This mode is also sometimes referred to as whole-sample symmetric.

'grid-wrap' (a b c d | a b c d | a b c d)

The input is extended by wrapping around to the opposite edge.

'wrap' (d b c d | a b c d | b c a b)

The input is extended by wrapping around to the opposite edge, but in a way such that the last point and initial point exactly overlap. In this case it is not well defined which sample will be chosen at the point of overlap.