Multidimensional binary propagation with the given structuring element.
Parameters ---------- input : array_like Binary image to be propagated inside `mask`. structure : array_like, optional Structuring element used in the successive dilations. The output may depend on the structuring element, especially if `mask` has several connex components. If no structuring element is provided, an element is generated with a squared connectivity equal to one. mask : array_like, optional Binary mask defining the region into which `input` is allowed to propagate. output : ndarray, optional Array of the same shape as input, into which the output is placed. By default, a new array is created. border_value : int (cast to 0 or 1), optional Value at the border in the output array. origin : int or tuple of ints, optional Placement of the filter, by default 0.
Returns ------- binary_propagation : ndarray Binary propagation of `input` inside `mask`.
Notes ----- This function is functionally equivalent to calling binary_dilation with the number of iterations less than one: iterative dilation until the result does not change anymore.
The succession of an erosion and propagation inside the original image can be used instead of an *opening* for deleting small objects while keeping the contours of larger objects untouched.
References ---------- .. 1
http://cmm.ensmp.fr/~serra/cours/pdf/en/ch6en.pdf, slide 15. .. 2
I.T. Young, J.J. Gerbrands, and L.J. van Vliet, 'Fundamentals of image processing', 1998 ftp://qiftp.tudelft.nl/DIPimage/docs/FIP2.3.pdf
Examples -------- >>> from scipy import ndimage >>> input = np.zeros((8, 8), dtype=int) >>> input2, 2
= 1 >>> mask = np.zeros((8, 8), dtype=int) >>> mask1:4, 1:4
= mask4, 4
= mask6:8, 6:8
= 1 >>> input array([0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 1, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0]
) >>> mask array([0, 0, 0, 0, 0, 0, 0, 0],
[0, 1, 1, 1, 0, 0, 0, 0],
[0, 1, 1, 1, 0, 0, 0, 0],
[0, 1, 1, 1, 0, 0, 0, 0],
[0, 0, 0, 0, 1, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 1, 1],
[0, 0, 0, 0, 0, 0, 1, 1]
) >>> ndimage.binary_propagation(input, mask=mask).astype(int) array([0, 0, 0, 0, 0, 0, 0, 0],
[0, 1, 1, 1, 0, 0, 0, 0],
[0, 1, 1, 1, 0, 0, 0, 0],
[0, 1, 1, 1, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0]
) >>> ndimage.binary_propagation(input, mask=mask,\ ... structure=np.ones((3,3))).astype(int) array([0, 0, 0, 0, 0, 0, 0, 0],
[0, 1, 1, 1, 0, 0, 0, 0],
[0, 1, 1, 1, 0, 0, 0, 0],
[0, 1, 1, 1, 0, 0, 0, 0],
[0, 0, 0, 0, 1, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0]
)
>>> # Comparison between opening and erosion+propagation >>> a = np.zeros((6,6), dtype=int) >>> a2:5, 2:5
= 1; a0, 0
= 1; a5, 5
= 1 >>> a array([1, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0],
[0, 0, 1, 1, 1, 0],
[0, 0, 1, 1, 1, 0],
[0, 0, 1, 1, 1, 0],
[0, 0, 0, 0, 0, 1]
) >>> ndimage.binary_opening(a).astype(int) array([0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0],
[0, 0, 0, 1, 0, 0],
[0, 0, 1, 1, 1, 0],
[0, 0, 0, 1, 0, 0],
[0, 0, 0, 0, 0, 0]
) >>> b = ndimage.binary_erosion(a) >>> b.astype(int) array([0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0],
[0, 0, 0, 1, 0, 0],
[0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0]
) >>> ndimage.binary_propagation(b, mask=a).astype(int) array([0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0],
[0, 0, 1, 1, 1, 0],
[0, 0, 1, 1, 1, 0],
[0, 0, 1, 1, 1, 0],
[0, 0, 0, 0, 0, 0]
)