# Licensed under a 3-clause BSD style license - see LICENSE.rst
import math
import numpy as np
from astropy.modeling import models
from astropy.modeling.core import Fittable1DModel, Fittable2DModel
from .core import Kernel, Kernel1D, Kernel2D
from .utils import has_even_axis, raise_even_kernel_exception
__all__ = [
"Gaussian1DKernel",
"Gaussian2DKernel",
"CustomKernel",
"Box1DKernel",
"Box2DKernel",
"Tophat2DKernel",
"Trapezoid1DKernel",
"RickerWavelet1DKernel",
"RickerWavelet2DKernel",
"AiryDisk2DKernel",
"Moffat2DKernel",
"Model1DKernel",
"Model2DKernel",
"TrapezoidDisk2DKernel",
"Ring2DKernel",
]
def _round_up_to_odd_integer(value):
i = math.ceil(value)
if i % 2 == 0:
return i + 1
else:
return i
[docs]class Gaussian1DKernel(Kernel1D):
"""
1D Gaussian filter kernel.
The Gaussian filter is a filter with great smoothing properties. It is
isotropic and does not produce artifacts.
The generated kernel is normalized so that it integrates to 1.
Parameters
----------
stddev : number
Standard deviation of the Gaussian kernel.
x_size : int, optional
Size of the kernel array. Default = ⌊8*stddev+1⌋.
mode : {'center', 'linear_interp', 'oversample', 'integrate'}, optional
One of the following discretization modes:
* 'center' (default)
Discretize model by taking the value
at the center of the bin.
* 'linear_interp'
Discretize model by linearly interpolating
between the values at the corners of the bin.
* 'oversample'
Discretize model by taking the average
on an oversampled grid.
* 'integrate'
Discretize model by integrating the
model over the bin. Very slow.
factor : number, optional
Factor of oversampling. Default factor = 10. If the factor
is too large, evaluation can be very slow.
See Also
--------
Box1DKernel, Trapezoid1DKernel, RickerWavelet1DKernel
Examples
--------
Kernel response:
.. plot::
:include-source:
import matplotlib.pyplot as plt
from astropy.convolution import Gaussian1DKernel
gauss_1D_kernel = Gaussian1DKernel(10)
plt.plot(gauss_1D_kernel, drawstyle='steps')
plt.xlabel('x [pixels]')
plt.ylabel('value')
plt.show()
"""
_separable = True
_is_bool = False
def __init__(self, stddev, **kwargs):
self._model = models.Gaussian1D(1.0 / (np.sqrt(2 * np.pi) * stddev), 0, stddev)
self._default_size = _round_up_to_odd_integer(8 * stddev)
super().__init__(**kwargs)
self.normalize()
[docs]class Gaussian2DKernel(Kernel2D):
"""
2D Gaussian filter kernel.
The Gaussian filter is a filter with great smoothing properties. It is
isotropic and does not produce artifacts.
The generated kernel is normalized so that it integrates to 1.
Parameters
----------
x_stddev : float
Standard deviation of the Gaussian in x before rotating by theta.
y_stddev : float
Standard deviation of the Gaussian in y before rotating by theta.
theta : float or `~astropy.units.Quantity` ['angle']
Rotation angle. If passed as a float, it is assumed to be in radians.
The rotation angle increases counterclockwise.
x_size : int, optional
Size in x direction of the kernel array. Default = ⌊8*stddev + 1⌋.
y_size : int, optional
Size in y direction of the kernel array. Default = ⌊8*stddev + 1⌋.
mode : {'center', 'linear_interp', 'oversample', 'integrate'}, optional
One of the following discretization modes:
* 'center' (default)
Discretize model by taking the value
at the center of the bin.
* 'linear_interp'
Discretize model by performing a bilinear interpolation
between the values at the corners of the bin.
* 'oversample'
Discretize model by taking the average
on an oversampled grid.
* 'integrate'
Discretize model by integrating the
model over the bin.
factor : number, optional
Factor of oversampling. Default factor = 10.
See Also
--------
Box2DKernel, Tophat2DKernel, RickerWavelet2DKernel, Ring2DKernel,
TrapezoidDisk2DKernel, AiryDisk2DKernel, Moffat2DKernel
Examples
--------
Kernel response:
.. plot::
:include-source:
import matplotlib.pyplot as plt
from astropy.convolution import Gaussian2DKernel
gaussian_2D_kernel = Gaussian2DKernel(10)
plt.imshow(gaussian_2D_kernel, interpolation='none', origin='lower')
plt.xlabel('x [pixels]')
plt.ylabel('y [pixels]')
plt.colorbar()
plt.show()
"""
_separable = True
_is_bool = False
def __init__(self, x_stddev, y_stddev=None, theta=0.0, **kwargs):
if y_stddev is None:
y_stddev = x_stddev
self._model = models.Gaussian2D(
amplitude=1.0 / (2 * np.pi * x_stddev * y_stddev),
x_mean=0,
y_mean=0,
x_stddev=x_stddev,
y_stddev=y_stddev,
theta=theta,
)
self._default_size = _round_up_to_odd_integer(8 * np.max([x_stddev, y_stddev]))
super().__init__(**kwargs)
self.normalize()
[docs]class Box1DKernel(Kernel1D):
"""
1D Box filter kernel.
The Box filter or running mean is a smoothing filter. It is not isotropic
and can produce artifacts when applied repeatedly to the same data.
The generated kernel is normalized so that it integrates to 1.
By default the Box kernel uses the ``linear_interp`` discretization mode,
which allows non-shifting, even-sized kernels. This is achieved by
weighting the edge pixels with 1/2. E.g a Box kernel with an effective
smoothing of 4 pixel would have the following array: [0.5, 1, 1, 1, 0.5].
Parameters
----------
width : number
Width of the filter kernel.
mode : {'linear_interp', 'center', 'oversample', 'integrate'}, optional
One of the following discretization modes:
* 'linear_interp' (default)
Discretize model by linearly interpolating
between the values at the corners of the bin.
* 'center'
Discretize model by taking the value
at the center of the bin.
* 'oversample'
Discretize model by taking the average
on an oversampled grid.
* 'integrate'
Discretize model by integrating the
model over the bin.
factor : number, optional
Factor of oversampling. Default factor = 10.
See Also
--------
Gaussian1DKernel, Trapezoid1DKernel, RickerWavelet1DKernel
Examples
--------
Kernel response function:
.. plot::
:include-source:
import matplotlib.pyplot as plt
from astropy.convolution import Box1DKernel
box_1D_kernel = Box1DKernel(9)
plt.plot(box_1D_kernel, drawstyle='steps')
plt.xlim(-1, 9)
plt.xlabel('x [pixels]')
plt.ylabel('value')
plt.show()
"""
_separable = True
_is_bool = True
def __init__(self, width, **kwargs):
self._model = models.Box1D(1.0 / width, 0, width)
self._default_size = _round_up_to_odd_integer(width)
kwargs["mode"] = "linear_interp"
super().__init__(**kwargs)
self.normalize()
[docs]class Box2DKernel(Kernel2D):
"""
2D Box filter kernel.
The Box filter or running mean is a smoothing filter. It is not isotropic
and can produce artifacts when applied repeatedly to the same data.
The generated kernel is normalized so that it integrates to 1.
By default the Box kernel uses the ``linear_interp`` discretization mode,
which allows non-shifting, even-sized kernels. This is achieved by
weighting the edge pixels with 1/2.
Parameters
----------
width : number
Width of the filter kernel.
mode : {'linear_interp', 'center', 'oversample', 'integrate'}, optional
One of the following discretization modes:
* 'linear_interp' (default)
Discretize model by performing a bilinear interpolation
between the values at the corners of the bin.
* 'center'
Discretize model by taking the value
at the center of the bin.
* 'oversample'
Discretize model by taking the average
on an oversampled grid.
* 'integrate'
Discretize model by integrating the
model over the bin.
factor : number, optional
Factor of oversampling. Default factor = 10.
See Also
--------
Gaussian2DKernel, Tophat2DKernel, RickerWavelet2DKernel, Ring2DKernel,
TrapezoidDisk2DKernel, AiryDisk2DKernel, Moffat2DKernel
Examples
--------
Kernel response:
.. plot::
:include-source:
import matplotlib.pyplot as plt
from astropy.convolution import Box2DKernel
box_2D_kernel = Box2DKernel(9)
plt.imshow(box_2D_kernel, interpolation='none', origin='lower',
vmin=0.0, vmax=0.015)
plt.xlim(-1, 9)
plt.ylim(-1, 9)
plt.xlabel('x [pixels]')
plt.ylabel('y [pixels]')
plt.colorbar()
plt.show()
"""
_separable = True
_is_bool = True
def __init__(self, width, **kwargs):
self._model = models.Box2D(1.0 / width**2, 0, 0, width, width)
self._default_size = _round_up_to_odd_integer(width)
kwargs["mode"] = "linear_interp"
super().__init__(**kwargs)
self.normalize()
[docs]class Tophat2DKernel(Kernel2D):
"""
2D Tophat filter kernel.
The Tophat filter is an isotropic smoothing filter. It can produce
artifacts when applied repeatedly on the same data.
The generated kernel is normalized so that it integrates to 1.
Parameters
----------
radius : int
Radius of the filter kernel.
mode : {'center', 'linear_interp', 'oversample', 'integrate'}, optional
One of the following discretization modes:
* 'center' (default)
Discretize model by taking the value
at the center of the bin.
* 'linear_interp'
Discretize model by performing a bilinear interpolation
between the values at the corners of the bin.
* 'oversample'
Discretize model by taking the average
on an oversampled grid.
* 'integrate'
Discretize model by integrating the
model over the bin.
factor : number, optional
Factor of oversampling. Default factor = 10.
See Also
--------
Gaussian2DKernel, Box2DKernel, RickerWavelet2DKernel, Ring2DKernel,
TrapezoidDisk2DKernel, AiryDisk2DKernel, Moffat2DKernel
Examples
--------
Kernel response:
.. plot::
:include-source:
import matplotlib.pyplot as plt
from astropy.convolution import Tophat2DKernel
tophat_2D_kernel = Tophat2DKernel(40)
plt.imshow(tophat_2D_kernel, interpolation='none', origin='lower')
plt.xlabel('x [pixels]')
plt.ylabel('y [pixels]')
plt.colorbar()
plt.show()
"""
def __init__(self, radius, **kwargs):
self._model = models.Disk2D(1.0 / (np.pi * radius**2), 0, 0, radius)
self._default_size = _round_up_to_odd_integer(2 * radius)
super().__init__(**kwargs)
self.normalize()
[docs]class Ring2DKernel(Kernel2D):
"""
2D Ring filter kernel.
The Ring filter kernel is the difference between two Tophat kernels of
different width. This kernel is useful for, e.g., background estimation.
The generated kernel is normalized so that it integrates to 1.
Parameters
----------
radius_in : number
Inner radius of the ring kernel.
width : number
Width of the ring kernel.
mode : {'center', 'linear_interp', 'oversample', 'integrate'}, optional
One of the following discretization modes:
* 'center' (default)
Discretize model by taking the value
at the center of the bin.
* 'linear_interp'
Discretize model by performing a bilinear interpolation
between the values at the corners of the bin.
* 'oversample'
Discretize model by taking the average
on an oversampled grid.
* 'integrate'
Discretize model by integrating the
model over the bin.
factor : number, optional
Factor of oversampling. Default factor = 10.
See Also
--------
Gaussian2DKernel, Box2DKernel, Tophat2DKernel, RickerWavelet2DKernel,
TrapezoidDisk2DKernel, AiryDisk2DKernel, Moffat2DKernel
Examples
--------
Kernel response:
.. plot::
:include-source:
import matplotlib.pyplot as plt
from astropy.convolution import Ring2DKernel
ring_2D_kernel = Ring2DKernel(9, 8)
plt.imshow(ring_2D_kernel, interpolation='none', origin='lower')
plt.xlabel('x [pixels]')
plt.ylabel('y [pixels]')
plt.colorbar()
plt.show()
"""
def __init__(self, radius_in, width, **kwargs):
radius_out = radius_in + width
self._model = models.Ring2D(
1.0 / (np.pi * (radius_out**2 - radius_in**2)), 0, 0, radius_in, width
)
self._default_size = _round_up_to_odd_integer(2 * radius_out)
super().__init__(**kwargs)
self.normalize()
[docs]class Trapezoid1DKernel(Kernel1D):
"""
1D trapezoid kernel.
The generated kernel is normalized so that it integrates to 1.
Parameters
----------
width : number
Width of the filter kernel, defined as the width of the constant part,
before it begins to slope down.
slope : number
Slope of the filter kernel's tails
mode : {'center', 'linear_interp', 'oversample', 'integrate'}, optional
One of the following discretization modes:
* 'center' (default)
Discretize model by taking the value
at the center of the bin.
* 'linear_interp'
Discretize model by linearly interpolating
between the values at the corners of the bin.
* 'oversample'
Discretize model by taking the average
on an oversampled grid.
* 'integrate'
Discretize model by integrating the
model over the bin.
factor : number, optional
Factor of oversampling. Default factor = 10.
See Also
--------
Box1DKernel, Gaussian1DKernel, RickerWavelet1DKernel
Examples
--------
Kernel response:
.. plot::
:include-source:
import matplotlib.pyplot as plt
from astropy.convolution import Trapezoid1DKernel
trapezoid_1D_kernel = Trapezoid1DKernel(17, slope=0.2)
plt.plot(trapezoid_1D_kernel, drawstyle='steps')
plt.xlabel('x [pixels]')
plt.ylabel('amplitude')
plt.xlim(-1, 28)
plt.show()
"""
_is_bool = False
def __init__(self, width, slope=1.0, **kwargs):
self._model = models.Trapezoid1D(1, 0, width, slope)
self._default_size = _round_up_to_odd_integer(width + 2.0 / slope)
super().__init__(**kwargs)
self.normalize()
[docs]class TrapezoidDisk2DKernel(Kernel2D):
"""
2D trapezoid kernel.
The generated kernel is normalized so that it integrates to 1.
Parameters
----------
radius : number
Width of the filter kernel, defined as the width of the constant part,
before it begins to slope down.
slope : number
Slope of the filter kernel's tails
mode : {'center', 'linear_interp', 'oversample', 'integrate'}, optional
One of the following discretization modes:
* 'center' (default)
Discretize model by taking the value
at the center of the bin.
* 'linear_interp'
Discretize model by performing a bilinear interpolation
between the values at the corners of the bin.
* 'oversample'
Discretize model by taking the average
on an oversampled grid.
* 'integrate'
Discretize model by integrating the
model over the bin.
factor : number, optional
Factor of oversampling. Default factor = 10.
See Also
--------
Gaussian2DKernel, Box2DKernel, Tophat2DKernel, RickerWavelet2DKernel,
Ring2DKernel, AiryDisk2DKernel, Moffat2DKernel
Examples
--------
Kernel response:
.. plot::
:include-source:
import matplotlib.pyplot as plt
from astropy.convolution import TrapezoidDisk2DKernel
trapezoid_2D_kernel = TrapezoidDisk2DKernel(20, slope=0.2)
plt.imshow(trapezoid_2D_kernel, interpolation='none', origin='lower')
plt.xlabel('x [pixels]')
plt.ylabel('y [pixels]')
plt.colorbar()
plt.show()
"""
_is_bool = False
def __init__(self, radius, slope=1.0, **kwargs):
self._model = models.TrapezoidDisk2D(1, 0, 0, radius, slope)
self._default_size = _round_up_to_odd_integer(2 * radius + 2.0 / slope)
super().__init__(**kwargs)
self.normalize()
[docs]class RickerWavelet1DKernel(Kernel1D):
"""
1D Ricker wavelet filter kernel (sometimes known as a "Mexican Hat"
kernel).
The Ricker wavelet, or inverted Gaussian-Laplace filter, is a
bandpass filter. It smooths the data and removes slowly varying
or constant structures (e.g. Background). It is useful for peak or
multi-scale detection.
This kernel is derived from a normalized Gaussian function, by
computing the second derivative. This results in an amplitude
at the kernels center of 1. / (sqrt(2 * pi) * width ** 3). The
normalization is the same as for `scipy.ndimage.gaussian_laplace`,
except for a minus sign.
.. note::
See https://github.com/astropy/astropy/pull/9445 for discussions
related to renaming of this kernel.
Parameters
----------
width : number
Width of the filter kernel, defined as the standard deviation
of the Gaussian function from which it is derived.
x_size : int, optional
Size in x direction of the kernel array. Default = ⌊8*width +1⌋.
mode : {'center', 'linear_interp', 'oversample', 'integrate'}, optional
One of the following discretization modes:
* 'center' (default)
Discretize model by taking the value
at the center of the bin.
* 'linear_interp'
Discretize model by linearly interpolating
between the values at the corners of the bin.
* 'oversample'
Discretize model by taking the average
on an oversampled grid.
* 'integrate'
Discretize model by integrating the
model over the bin.
factor : number, optional
Factor of oversampling. Default factor = 10.
See Also
--------
Box1DKernel, Gaussian1DKernel, Trapezoid1DKernel
Examples
--------
Kernel response:
.. plot::
:include-source:
import matplotlib.pyplot as plt
from astropy.convolution import RickerWavelet1DKernel
ricker_1d_kernel = RickerWavelet1DKernel(10)
plt.plot(ricker_1d_kernel, drawstyle='steps')
plt.xlabel('x [pixels]')
plt.ylabel('value')
plt.show()
"""
_is_bool = True
def __init__(self, width, **kwargs):
amplitude = 1.0 / (np.sqrt(2 * np.pi) * width**3)
self._model = models.RickerWavelet1D(amplitude, 0, width)
self._default_size = _round_up_to_odd_integer(8 * width)
super().__init__(**kwargs)
[docs]class RickerWavelet2DKernel(Kernel2D):
"""
2D Ricker wavelet filter kernel (sometimes known as a "Mexican Hat"
kernel).
The Ricker wavelet, or inverted Gaussian-Laplace filter, is a
bandpass filter. It smooths the data and removes slowly varying
or constant structures (e.g. Background). It is useful for peak or
multi-scale detection.
This kernel is derived from a normalized Gaussian function, by
computing the second derivative. This results in an amplitude
at the kernels center of 1. / (pi * width ** 4). The normalization
is the same as for `scipy.ndimage.gaussian_laplace`, except
for a minus sign.
.. note::
See https://github.com/astropy/astropy/pull/9445 for discussions
related to renaming of this kernel.
Parameters
----------
width : number
Width of the filter kernel, defined as the standard deviation
of the Gaussian function from which it is derived.
x_size : int, optional
Size in x direction of the kernel array. Default = ⌊8*width +1⌋.
y_size : int, optional
Size in y direction of the kernel array. Default = ⌊8*width +1⌋.
mode : {'center', 'linear_interp', 'oversample', 'integrate'}, optional
One of the following discretization modes:
* 'center' (default)
Discretize model by taking the value
at the center of the bin.
* 'linear_interp'
Discretize model by performing a bilinear interpolation
between the values at the corners of the bin.
* 'oversample'
Discretize model by taking the average
on an oversampled grid.
* 'integrate'
Discretize model by integrating the
model over the bin.
factor : number, optional
Factor of oversampling. Default factor = 10.
See Also
--------
Gaussian2DKernel, Box2DKernel, Tophat2DKernel, Ring2DKernel,
TrapezoidDisk2DKernel, AiryDisk2DKernel, Moffat2DKernel
Examples
--------
Kernel response:
.. plot::
:include-source:
import matplotlib.pyplot as plt
from astropy.convolution import RickerWavelet2DKernel
ricker_2d_kernel = RickerWavelet2DKernel(10)
plt.imshow(ricker_2d_kernel, interpolation='none', origin='lower')
plt.xlabel('x [pixels]')
plt.ylabel('y [pixels]')
plt.colorbar()
plt.show()
"""
_is_bool = False
def __init__(self, width, **kwargs):
amplitude = 1.0 / (np.pi * width**4)
self._model = models.RickerWavelet2D(amplitude, 0, 0, width)
self._default_size = _round_up_to_odd_integer(8 * width)
super().__init__(**kwargs)
[docs]class AiryDisk2DKernel(Kernel2D):
"""
2D Airy disk kernel.
This kernel models the diffraction pattern of a circular aperture.
The generated kernel is normalized so that it integrates to 1.
Parameters
----------
radius : float
The radius of the Airy disk kernel (radius of the first zero).
x_size : int, optional
Size in x direction of the kernel array. Default = ⌊8*radius + 1⌋.
y_size : int, optional
Size in y direction of the kernel array. Default = ⌊8*radius + 1⌋.
mode : {'center', 'linear_interp', 'oversample', 'integrate'}, optional
One of the following discretization modes:
* 'center' (default)
Discretize model by taking the value
at the center of the bin.
* 'linear_interp'
Discretize model by performing a bilinear interpolation
between the values at the corners of the bin.
* 'oversample'
Discretize model by taking the average
on an oversampled grid.
* 'integrate'
Discretize model by integrating the
model over the bin.
factor : number, optional
Factor of oversampling. Default factor = 10.
See Also
--------
Gaussian2DKernel, Box2DKernel, Tophat2DKernel, RickerWavelet2DKernel,
Ring2DKernel, TrapezoidDisk2DKernel, Moffat2DKernel
Examples
--------
Kernel response:
.. plot::
:include-source:
import matplotlib.pyplot as plt
from astropy.convolution import AiryDisk2DKernel
airydisk_2D_kernel = AiryDisk2DKernel(10)
plt.imshow(airydisk_2D_kernel, interpolation='none', origin='lower')
plt.xlabel('x [pixels]')
plt.ylabel('y [pixels]')
plt.colorbar()
plt.show()
"""
_is_bool = False
def __init__(self, radius, **kwargs):
self._model = models.AiryDisk2D(1, 0, 0, radius)
self._default_size = _round_up_to_odd_integer(8 * radius)
super().__init__(**kwargs)
self.normalize()
[docs]class Moffat2DKernel(Kernel2D):
"""
2D Moffat kernel.
This kernel is a typical model for a seeing limited PSF.
The generated kernel is normalized so that it integrates to 1.
Parameters
----------
gamma : float
Core width of the Moffat model.
alpha : float
Power index of the Moffat model.
x_size : int, optional
Size in x direction of the kernel array. Default = ⌊8*radius + 1⌋.
y_size : int, optional
Size in y direction of the kernel array. Default = ⌊8*radius + 1⌋.
mode : {'center', 'linear_interp', 'oversample', 'integrate'}, optional
One of the following discretization modes:
* 'center' (default)
Discretize model by taking the value
at the center of the bin.
* 'linear_interp'
Discretize model by performing a bilinear interpolation
between the values at the corners of the bin.
* 'oversample'
Discretize model by taking the average
on an oversampled grid.
* 'integrate'
Discretize model by integrating the
model over the bin.
factor : number, optional
Factor of oversampling. Default factor = 10.
See Also
--------
Gaussian2DKernel, Box2DKernel, Tophat2DKernel, RickerWavelet2DKernel,
Ring2DKernel, TrapezoidDisk2DKernel, AiryDisk2DKernel
Examples
--------
Kernel response:
.. plot::
:include-source:
import matplotlib.pyplot as plt
from astropy.convolution import Moffat2DKernel
moffat_2D_kernel = Moffat2DKernel(3, 2)
plt.imshow(moffat_2D_kernel, interpolation='none', origin='lower')
plt.xlabel('x [pixels]')
plt.ylabel('y [pixels]')
plt.colorbar()
plt.show()
"""
_is_bool = False
def __init__(self, gamma, alpha, **kwargs):
# Compute amplitude, from
# https://en.wikipedia.org/wiki/Moffat_distribution
amplitude = (alpha - 1.0) / (np.pi * gamma * gamma)
self._model = models.Moffat2D(amplitude, 0, 0, gamma, alpha)
self._default_size = _round_up_to_odd_integer(4.0 * self._model.fwhm)
super().__init__(**kwargs)
self.normalize()
[docs]class Model1DKernel(Kernel1D):
"""
Create kernel from 1D model.
The model has to be centered on x = 0.
Parameters
----------
model : `~astropy.modeling.Fittable1DModel`
Kernel response function model
x_size : int, optional
Size in x direction of the kernel array. Default = ⌊8*width +1⌋.
Must be odd.
mode : {'center', 'linear_interp', 'oversample', 'integrate'}, optional
One of the following discretization modes:
* 'center' (default)
Discretize model by taking the value
at the center of the bin.
* 'linear_interp'
Discretize model by linearly interpolating
between the values at the corners of the bin.
* 'oversample'
Discretize model by taking the average
on an oversampled grid.
* 'integrate'
Discretize model by integrating the
model over the bin.
factor : number, optional
Factor of oversampling. Default factor = 10.
Raises
------
TypeError
If model is not an instance of `~astropy.modeling.Fittable1DModel`
See also
--------
Model2DKernel : Create kernel from `~astropy.modeling.Fittable2DModel`
CustomKernel : Create kernel from list or array
Examples
--------
Define a Gaussian1D model:
>>> from astropy.modeling.models import Gaussian1D
>>> from astropy.convolution.kernels import Model1DKernel
>>> gauss = Gaussian1D(1, 0, 2)
And create a custom one dimensional kernel from it:
>>> gauss_kernel = Model1DKernel(gauss, x_size=9)
This kernel can now be used like a usual Astropy kernel.
"""
_separable = False
_is_bool = False
def __init__(self, model, **kwargs):
if isinstance(model, Fittable1DModel):
self._model = model
else:
raise TypeError("Must be Fittable1DModel")
super().__init__(**kwargs)
[docs]class Model2DKernel(Kernel2D):
"""
Create kernel from 2D model.
The model has to be centered on x = 0 and y = 0.
Parameters
----------
model : `~astropy.modeling.Fittable2DModel`
Kernel response function model
x_size : int, optional
Size in x direction of the kernel array. Default = ⌊8*width +1⌋.
Must be odd.
y_size : int, optional
Size in y direction of the kernel array. Default = ⌊8*width +1⌋.
mode : {'center', 'linear_interp', 'oversample', 'integrate'}, optional
One of the following discretization modes:
* 'center' (default)
Discretize model by taking the value
at the center of the bin.
* 'linear_interp'
Discretize model by performing a bilinear interpolation
between the values at the corners of the bin.
* 'oversample'
Discretize model by taking the average
on an oversampled grid.
* 'integrate'
Discretize model by integrating the
model over the bin.
factor : number, optional
Factor of oversampling. Default factor = 10.
Raises
------
TypeError
If model is not an instance of `~astropy.modeling.Fittable2DModel`
See also
--------
Model1DKernel : Create kernel from `~astropy.modeling.Fittable1DModel`
CustomKernel : Create kernel from list or array
Examples
--------
Define a Gaussian2D model:
>>> from astropy.modeling.models import Gaussian2D
>>> from astropy.convolution.kernels import Model2DKernel
>>> gauss = Gaussian2D(1, 0, 0, 2, 2)
And create a custom two dimensional kernel from it:
>>> gauss_kernel = Model2DKernel(gauss, x_size=9)
This kernel can now be used like a usual astropy kernel.
"""
_is_bool = False
_separable = False
def __init__(self, model, **kwargs):
self._separable = False
if isinstance(model, Fittable2DModel):
self._model = model
else:
raise TypeError("Must be Fittable2DModel")
super().__init__(**kwargs)
[docs]class CustomKernel(Kernel):
"""
Create filter kernel from list or array.
Parameters
----------
array : list or array
Filter kernel array. Size must be odd.
Raises
------
TypeError
If array is not a list or array.
`~astropy.convolution.KernelSizeError`
If array size is even.
See also
--------
Model2DKernel, Model1DKernel
Examples
--------
Define one dimensional array:
>>> from astropy.convolution.kernels import CustomKernel
>>> import numpy as np
>>> array = np.array([1, 2, 3, 2, 1])
>>> kernel = CustomKernel(array)
>>> kernel.dimension
1
Define two dimensional array:
>>> array = np.array([[1, 1, 1], [1, 2, 1], [1, 1, 1]])
>>> kernel = CustomKernel(array)
>>> kernel.dimension
2
"""
def __init__(self, array):
self.array = array
super().__init__(self._array)
@property
def array(self):
"""
Filter kernel array.
"""
return self._array
@array.setter
def array(self, array):
"""
Filter kernel array setter
"""
if isinstance(array, np.ndarray):
self._array = array.astype(np.float64)
elif isinstance(array, list):
self._array = np.array(array, dtype=np.float64)
else:
raise TypeError("Must be list or array.")
# Check if array is odd in all axes
if has_even_axis(self):
raise_even_kernel_exception()
# Check if array is bool
ones = self._array == 1.0
zeros = self._array == 0
self._is_bool = bool(np.all(np.logical_or(ones, zeros)))