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Module « scipy.signal »

Fonction convolve2d - module scipy.signal

Signature de la fonction convolve2d

def convolve2d(in1, in2, mode='full', boundary='fill', fillvalue=0) 

Description

help(scipy.signal.convolve2d)

Convolve two 2-dimensional arrays.

Convolve `in1` and `in2` with output size determined by `mode`, and
boundary conditions determined by `boundary` and `fillvalue`.

Parameters
----------
in1 : array_like
    First input.
in2 : array_like
    Second input. Should have the same number of dimensions as `in1`.
mode : str {'full', 'valid', 'same'}, optional
    A string indicating the size of the output:

    ``full``
       The output is the full discrete linear convolution
       of the inputs. (Default)
    ``valid``
       The output consists only of those elements that do not
       rely on the zero-padding. In 'valid' mode, either `in1` or `in2`
       must be at least as large as the other in every dimension.
    ``same``
       The output is the same size as `in1`, centered
       with respect to the 'full' output.
boundary : str {'fill', 'wrap', 'symm'}, optional
    A flag indicating how to handle boundaries:

    ``fill``
       pad input arrays with fillvalue. (default)
    ``wrap``
       circular boundary conditions.
    ``symm``
       symmetrical boundary conditions.

fillvalue : scalar, optional
    Value to fill pad input arrays with. Default is 0.

Returns
-------
out : ndarray
    A 2-dimensional array containing a subset of the discrete linear
    convolution of `in1` with `in2`.

Examples
--------
Compute the gradient of an image by 2D convolution with a complex Scharr
operator.  (Horizontal operator is real, vertical is imaginary.)  Use
symmetric boundary condition to avoid creating edges at the image
boundaries.

>>> import numpy as np
>>> from scipy import signal
>>> from scipy import datasets
>>> ascent = datasets.ascent()
>>> scharr = np.array([[ -3-3j, 0-10j,  +3 -3j],
...                    [-10+0j, 0+ 0j, +10 +0j],
...                    [ -3+3j, 0+10j,  +3 +3j]]) # Gx + j*Gy
>>> grad = signal.convolve2d(ascent, scharr, boundary='symm', mode='same')

>>> import matplotlib.pyplot as plt
>>> fig, (ax_orig, ax_mag, ax_ang) = plt.subplots(3, 1, figsize=(6, 15))
>>> ax_orig.imshow(ascent, cmap='gray')
>>> ax_orig.set_title('Original')
>>> ax_orig.set_axis_off()
>>> ax_mag.imshow(np.absolute(grad), cmap='gray')
>>> ax_mag.set_title('Gradient magnitude')
>>> ax_mag.set_axis_off()
>>> ax_ang.imshow(np.angle(grad), cmap='hsv') # hsv is cyclic, like angles
>>> ax_ang.set_title('Gradient orientation')
>>> ax_ang.set_axis_off()
>>> fig.show()



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