/usr/lib/python2.7/dist-packages/photutils/utils/convolution.py is in python-photutils 0.4-1.
This file is owned by root:root, with mode 0o644.
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from __future__ import (absolute_import, division, print_function,
unicode_literals)
import warnings
import numpy as np
from astropy.convolution import Kernel2D
from astropy.utils.exceptions import AstropyUserWarning
__all__ = ['filter_data']
def filter_data(data, kernel, mode='constant', fill_value=0.0,
check_normalization=False):
"""
Convolve a 2D image with a 2D kernel.
The kernel may either be a 2D `~numpy.ndarray` or a
`~astropy.convolution.Kernel2D` object.
Parameters
----------
data : array_like
The 2D array of the image.
kernel : array-like (2D) or `~astropy.convolution.Kernel2D`
The 2D kernel used to filter the input ``data``. Filtering the
``data`` will smooth the noise and maximize detectability of
objects with a shape similar to the kernel.
mode : {'constant', 'reflect', 'nearest', 'mirror', 'wrap'}, optional
The ``mode`` determines how the array borders are handled. For
the ``'constant'`` mode, values outside the array borders are
set to ``fill_value``. The default is ``'constant'``.
fill_value : scalar, optional
Value to fill data values beyond the array borders if ``mode``
is ``'constant'``. The default is ``0.0``.
check_normalization : bool, optional
If `True` then a warning will be issued if the kernel is not
normalized to 1.
"""
from scipy import ndimage
if kernel is not None:
if isinstance(kernel, Kernel2D):
kernel_array = kernel.array
else:
kernel_array = kernel
if check_normalization:
if not np.allclose(np.sum(kernel_array), 1.0):
warnings.warn('The kernel is not normalized.',
AstropyUserWarning)
# NOTE: astropy.convolution.convolve fails with zero-sum
# kernels (used in findstars) (cf. astropy #1647)
return ndimage.convolve(data, kernel_array, mode=mode,
cval=fill_value)
else:
return data
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