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MAINT: put AA method in draw.*_aa

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François Boulogne
2013-10-02 17:24:22 +02:00
parent dcf02235a4
commit 2606494828
4 changed files with 97 additions and 68 deletions
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doc/examples/plot_shapes.py
+3 -2
View File
@@ -14,7 +14,8 @@ This example shows how to fill several different shapes:
import numpy as np
import matplotlib.pyplot as plt
from skimage.draw import line, polygon, circle, circle_perimeter, \
from skimage.draw import line, polygon, circle, \
circle_perimeter, circle_perimeter_aa, \
ellipse, ellipse_perimeter
import numpy as np
import math
@@ -49,7 +50,7 @@ rr, cc = circle_perimeter(120, 400, 15)
img[rr, cc, :] = (255, 0, 0)
# anti-aliased circle
rr, cc, val = circle_perimeter(120, 400, 70, 'wu')
rr, cc, val = circle_perimeter_aa(120, 400, 70)
img[rr, cc, 1] = val * 255
# ellipses
skimage/draw/__init__.py
+3 -2
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@@ -1,6 +1,6 @@
from .draw import circle, ellipse, set_color
from ._draw import line, polygon, ellipse_perimeter, circle_perimeter, \
bezier_segment
from ._draw import (line, polygon, ellipse_perimeter, circle_perimeter,
circle_perimeter_aa, bezier_segment)
from .draw3d import ellipsoid, ellipsoid_stats
__all__ = ['line',
@@ -11,4 +11,5 @@ __all__ = ['line',
'ellipsoid_stats',
'circle',
'circle_perimeter',
'circle_perimeter_aa',
'set_color']
skimage/draw/_draw.pyx
+84 -59
View File
@@ -178,7 +178,6 @@ def circle_perimeter(Py_ssize_t cy, Py_ssize_t cx, Py_ssize_t radius,
method : {'bresenham', 'andres', 'wu'}, optional
bresenham : Bresenham method (default)
andres : Andres method
wu : Wu's method
Returns
-------
@@ -188,19 +187,13 @@ def circle_perimeter(Py_ssize_t cy, Py_ssize_t cx, Py_ssize_t radius,
May be used to directly index into an array, e.g.
``img[rr, cc] = 1``.
rr, cc, val : (N,) ndarray of int
Wu's method:
Indices of pixels and intensity values.
``img[rr, cc] = val``.
Notes
-----
Andres method presents the advantage that concentric
circles create a disc whereas Bresenham can make holes. There
is also less distortions when Andres circles are rotated.
Bresenham method is also known as midpoint circle algorithm.
Wu's method draws anti-aliased circle. This implementation doesn't use
lookup table optimization.
Anti-aliased circle generator is available with `circle_perimeter_aa`.
References
----------
@@ -208,8 +201,6 @@ def circle_perimeter(Py_ssize_t cy, Py_ssize_t cx, Py_ssize_t radius,
plotter", IBM Systems journal, 4 (1965) 25-30.
.. [2] E. Andres, "Discrete circles, rings and spheres", Computers &
Graphics, 18 (1994) 695-706.
.. [3] X. Wu, "An efficient antialiasing technique", In ACM SIGGRAPH
Computer Graphics, 25 (1991) 143-152.
Examples
--------
@@ -233,7 +224,6 @@ def circle_perimeter(Py_ssize_t cy, Py_ssize_t cx, Py_ssize_t radius,
cdef list rr = list()
cdef list cc = list()
cdef list val = list()
cdef Py_ssize_t x = 0
cdef Py_ssize_t y = radius
@@ -249,62 +239,97 @@ def circle_perimeter(Py_ssize_t cy, Py_ssize_t cx, Py_ssize_t radius,
elif method == 'andres':
d = radius - 1
cmethod = 'a'
elif method == 'wu':
cmethod = 'w'
else:
raise ValueError('Wrong method')
if cmethod == 'a' or cmethod == 'b':
while y >= x:
rr.extend([y, -y, y, -y, x, -x, x, -x])
cc.extend([x, x, -x, -x, y, y, -y, -y])
while y >= x:
rr.extend([y, -y, y, -y, x, -x, x, -x])
cc.extend([x, x, -x, -x, y, y, -y, -y])
if cmethod == 'b':
if d < 0:
d += 4 * x + 6
else:
d += 4 * (x - y) + 10
y -= 1
x += 1
elif cmethod == 'a':
if d >= 2 * (x - 1):
d = d - 2 * x
x = x + 1
elif d <= 2 * (radius - y):
d = d + 2 * y - 1
y = y - 1
else:
d = d + 2 * (y - x - 1)
y = y - 1
x = x + 1
return (np.array(rr, dtype=np.intp) + cy,
np.array(cc, dtype=np.intp) + cx)
elif cmethod == 'w':
dceil_prev = 0
rr.extend([y, x, y, x, -y, -x, -y, -x])
cc.extend([x, y, -x, -y, x, y, -x, -y])
val.extend([1] * 8)
while y > x + 1:
x += 1
dceil = math.sqrt(radius**2 - x**2)
dceil = math.ceil(dceil) - dceil
if dceil < dceil_prev:
if cmethod == 'b':
if d < 0:
d += 4 * x + 6
else:
d += 4 * (x - y) + 10
y -= 1
rr.extend([y, y - 1, x, x, y, y - 1, x, x])
cc.extend([x, x, y, y - 1, -x, -x, -y, 1 - y])
x += 1
elif cmethod == 'a':
if d >= 2 * (x - 1):
d = d - 2 * x
x = x + 1
elif d <= 2 * (radius - y):
d = d + 2 * y - 1
y = y - 1
else:
d = d + 2 * (y - x - 1)
y = y - 1
x = x + 1
return (np.array(rr, dtype=np.intp) + cy,
np.array(cc, dtype=np.intp) + cx)
rr.extend([-y, 1 - y, -x, -x, -y, 1 - y, -x, -x])
cc.extend([x, x, y, y - 1, -x, -x, -y, 1 - y])
val.extend([1 - dceil, dceil] * 8)
dceil_prev = dceil
def circle_perimeter_aa(Py_ssize_t cy, Py_ssize_t cx, Py_ssize_t radius):
"""Generate anti-aliased circle perimeter coordinates.
return (np.array(rr, dtype=np.intp) + cy,
np.array(cc, dtype=np.intp) + cx,
np.array(val, dtype=np.float))
Parameters
----------
cy, cx : int
Centre coordinate of circle.
radius: int
Radius of circle.
Returns
-------
rr, cc, val : (N,) ndarray of int
Indices of pixels (`rr`, `cc`) and intensity values (`val`).
``img[rr, cc] = val``.
Notes
-----
Wu's method draws anti-aliased circle. This implementation doesn't use
lookup table optimization.
References
----------
.. [1] X. Wu, "An efficient antialiasing technique", In ACM SIGGRAPH
Computer Graphics, 25 (1991) 143-152.
"""
cdef list rr = list()
cdef list cc = list()
cdef list val = list()
cdef Py_ssize_t x = 0
cdef Py_ssize_t y = radius
cdef Py_ssize_t d = 0
cdef double dceil = 0
dceil_prev = 0
rr.extend([y, x, y, x, -y, -x, -y, -x])
cc.extend([x, y, -x, -y, x, y, -x, -y])
val.extend([1] * 8)
while y > x + 1:
x += 1
dceil = math.sqrt(radius**2 - x**2)
dceil = math.ceil(dceil) - dceil
if dceil < dceil_prev:
y -= 1
rr.extend([y, y - 1, x, x, y, y - 1, x, x])
cc.extend([x, x, y, y - 1, -x, -x, -y, 1 - y])
rr.extend([-y, 1 - y, -x, -x, -y, 1 - y, -x, -x])
cc.extend([x, x, y, y - 1, -x, -x, -y, 1 - y])
val.extend([1 - dceil, dceil] * 8)
dceil_prev = dceil
return (np.array(rr, dtype=np.intp) + cy,
np.array(cc, dtype=np.intp) + cx,
np.array(val, dtype=np.float))
def ellipse_perimeter(Py_ssize_t cy, Py_ssize_t cx, Py_ssize_t yradius,
skimage/draw/tests/test_draw.py
+7 -5
View File
@@ -1,8 +1,10 @@
from numpy.testing import assert_array_equal
import numpy as np
from skimage.draw import line, polygon, circle, circle_perimeter, \
ellipse, ellipse_perimeter, bezier_segment
from skimage.draw import (line, polygon, circle, circle_perimeter,
circle_perimeter_aa, ellipse,
ellipse_perimeter, bezier_segment,
)
def test_line_horizontal():
@@ -215,15 +217,15 @@ def test_circle_perimeter_andres():
assert_array_equal(img, img_)
def test_circle_perimeter_wu():
def test_circle_perimeter_aa():
img = np.zeros((15, 15), 'uint8')
rr, cc, val = circle_perimeter(7, 7, 0, method='wu')
rr, cc, val = circle_perimeter_aa(7, 7, 0)
img[rr, cc] = 1
assert(np.sum(img) == 1)
assert(img[7][7] == 1)
img = np.zeros((17, 17), 'uint8')
rr, cc, val = circle_perimeter(8, 8, 7, method='wu')
rr, cc, val = circle_perimeter_aa(8, 8, 7)
img[rr, cc] = val * 255
img_ = np.array(
[[ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],