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https://github.com/wassname/scikit-image.git
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new method: ellipse_perimeter
This commit is contained in:
François Boulogne
@@ -1,2 +1,2 @@
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from ._draw import line, polygon, ellipse, circle, circle_perimeter, set_color
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from ._draw import line, polygon, ellipse, circle, circle_perimeter, ellipse_perimeter, set_color
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bresenham = line
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@@ -263,6 +263,90 @@ def circle_perimeter(int cy, int cx, int radius, method='bresenham'):
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return np.array(rr) + cy, np.array(cc) + cx
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def ellipse_perimeter(int cy, int cx, int yradius, int xradius):
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"""Generate ellipse perimeter coordinates.
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Parameters
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----------
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cy, cx : int
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Centre coordinate of ellipse.
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yradius, xradius: int
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Main radial values.
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Returns
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-------
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rr, cc : (N,) ndarray of int
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Indices of pixels that belong to the circle perimeter.
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May be used to directly index into an array, e.g.
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``img[rr, cc] = 1``.
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References
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----------
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.. [1] J. Kennedy "A fast Bresenham type algorithm for
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drawing ellipses".
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"""
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# If both radii == 0, return the center
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# to avoid infinite loop in 2nd set
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if (xradius == 0 and yradius == 0):
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return np.array(cy), np.array(cx)
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# a and b are xradius an yradius
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# compute 2a^2 and 2b^2
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cdef int twoasquared = 2 * xradius * xradius
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cdef int twobsquared = 2 * yradius * yradius
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# Pixels
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cdef list px = list()
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cdef list py = list()
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# First set of points:
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# start at the top
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cdef int x = xradius
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cdef int y = 0
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cdef int err = 0
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cdef int xstop = twobsquared * xradius
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cdef int ystop = 0
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cdef int xchange = yradius * yradius * (1 - 2 * xradius)
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cdef int ychange = xradius * xradius
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while(xstop > ystop):
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px.extend([x, -x, -x, x])
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py.extend([y, y, -y, -y])
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y += 1
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ystop += twoasquared
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err += ychange
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ychange += twoasquared
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if ((2 * err + xchange) > 0):
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x -= 1
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xstop -= twobsquared
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err += xchange
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xchange += twobsquared
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# Second set of points:
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x = 0
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y = yradius
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err = 0
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xstop = 0
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ystop = twoasquared * yradius
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xchange = yradius * yradius
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ychange = xradius * xradius * (1 - 2 * yradius)
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while(xstop <= ystop):
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px.extend([x, -x, -x, x])
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py.extend([y, y, -y, -y])
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x += 1
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xstop += twobsquared
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err += xchange
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xchange += twobsquared
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if ((2 * err + ychange) > 0):
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y -= 1
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ystop -= twoasquared
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err += ychange
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ychange += twobsquared
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return np.array(py) + cy, np.array(px) + cx
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@cython.boundscheck(False)
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@cython.wraparound(False)
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@@ -1,7 +1,7 @@
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from numpy.testing import assert_array_equal
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import numpy as np
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from skimage.draw import line, polygon, circle, circle_perimeter, ellipse
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from skimage.draw import line, polygon, circle, circle_perimeter, ellipse, ellipse_perimeter
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def test_line_horizontal():
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@@ -210,7 +210,6 @@ def test_circle_perimeter_andres():
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)
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assert_array_equal(img, img_)
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def test_ellipse():
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img = np.zeros((15, 15), 'uint8')
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@@ -237,6 +236,50 @@ def test_ellipse():
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assert_array_equal(img, img_)
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def test_ellipse_perimeter():
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img = np.zeros((30, 15), 'uint8')
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rr, cc = ellipse_perimeter(15, 7, 0, 0)
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img[rr, cc] = 1
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assert(np.sum(img) == 1)
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img = np.zeros((30, 15), 'uint8')
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rr, cc = ellipse_perimeter(15, 7, 14, 6)
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img[rr, cc] = 1
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print(img)
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img_ = np.array(
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[[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
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[0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0],
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[0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0],
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[0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0],
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[0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0],
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[0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0],
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[0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0],
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[0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0],
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[0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0],
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[0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0],
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[0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0],
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[0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0],
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[0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0],
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[0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0],
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[0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0],
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[0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0],
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[0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0],
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[0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0],
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[0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0],
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[0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0],
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[0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0],
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[0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0],
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[0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0],
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[0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0],
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[0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0],
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[0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0],
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[0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0],
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[0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0],
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[0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0],
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[0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0]]
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)
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assert_array_equal(img, img_)
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if __name__ == "__main__":
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from numpy.testing import run_module_suite
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