scipy.ndimage.

fourier_uniform#

scipy.ndimage.fourier_uniform(input, size, n=-1, axis=-1, output=None)[source]#

Multidimensional uniform fourier filter.

The array is multiplied with the Fourier transform of a box of given size.

Parameters:
inputarray_like

The input array.

sizefloat or sequence

The size of the box used for filtering. If a float, size is the same for all axes. If a sequence, size has to contain one value for each axis.

nint, optional

If n is negative (default), then the input is assumed to be the result of a complex fft. If n is larger than or equal to zero, the input is assumed to be the result of a real fft, and n gives the length of the array before transformation along the real transform direction.

axisint, optional

The axis of the real transform.

outputndarray, optional

If given, the result of filtering the input is placed in this array.

Returns:
fourier_uniformndarray

The filtered input.

Notes

Array API Standard Support

fourier_uniform has experimental support for Python Array API Standard compatible backends in addition to NumPy. Please consider testing these features by setting an environment variable SCIPY_ARRAY_API=1 and providing CuPy, PyTorch, JAX, or Dask arrays as array arguments. The following combinations of backend and device (or other capability) are supported.

Library

CPU

GPU

NumPy

n/a

CuPy

n/a

PyTorch

JAX

⚠️ no JIT

Dask

⚠️ computes graph

n/a

See Support for the array API standard for more information.

Examples

>>> from scipy import ndimage, datasets
>>> import numpy.fft
>>> import matplotlib.pyplot as plt
>>> fig, (ax1, ax2) = plt.subplots(1, 2)
>>> plt.gray()  # show the filtered result in grayscale
>>> ascent = datasets.ascent()
>>> input_ = numpy.fft.fft2(ascent)
>>> result = ndimage.fourier_uniform(input_, size=20)
>>> result = numpy.fft.ifft2(result)
>>> ax1.imshow(ascent)
>>> ax2.imshow(result.real)  # the imaginary part is an artifact
>>> plt.show()
../../_images/scipy-ndimage-fourier_uniform-1.png