code: def _filter_input(image, prefilter, mode, cval, order):
      """Perform spline prefiltering when needed.
  
      Spline orders > 1 need a prefiltering stage to preserve resolution.
  
      For boundary modes without analytical spline boundary conditions, some
      prepadding of the input with cupy.pad is used to maintain accuracy.
      ``npad`` is an integer corresponding to the amount of padding at each edge
      of the array.
      """
      if not prefilter or order < 2:
          return (cupy.ascontiguousarray(image), 0)
      padded, npad = _prepad_for_spline_filter(image, mode, cval)
      float_dtype = cupy.promote_types(image.dtype, cupy.float32)
      filtered = spline_filter(
          padded, order, output=float_dtype, mode=mode
      )
      return cupy.ascontiguousarray(filtered), npad
  
imports: import math
  import warnings
  import cupy
  import numpy
  from cupy import _core
  from cupy._core import internal
  from cupy.cuda import runtime
  from cupyx import _texture
  from cupyx.scipy.ndimage import _util
  from cupyx.scipy.ndimage import _interp_kernels
  from cupyx.scipy.ndimage import _spline_prefilter_core
label_desc: Use image node_id 7 for calling a global function with example usage: _filter_input(image, prefilter, mode, cval, order) and returns: cupy,  npad, cupy,  int