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Merge pull request #177 from ahojnnes/draw-polygon-alt
ENH: Polygon, circle and ellipse drawing.
This commit is contained in:
Stefan van der Walt
@@ -98,3 +98,6 @@
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- Nicolas Poilvert
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Shape views: ``util.shape.view_as_windows`` and ``util.shape.view_as_blocks``
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- Johannes Schönberger
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Polygon, circle and ellipse drawing functions
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@@ -0,0 +1,46 @@
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"""
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===========
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Fill shapes
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===========
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This example shows how to fill several different shapes:
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* line
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* polygon
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* circle
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* ellipse
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"""
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import matplotlib.pyplot as plt
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from skimage.draw import line, polygon, circle, ellipse
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import numpy as np
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img = np.zeros((500, 500, 3), 'uint8')
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#: draw line
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rr, cc = line(120, 123, 20, 400)
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img[rr,cc,0] = 255
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#: fill polygon
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poly = np.array((
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(300, 300),
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(480, 320),
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(380, 430),
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(220, 590),
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(300, 300),
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))
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rr, cc = polygon(poly[:,0], poly[:,1], img.shape)
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img[rr,cc,1] = 255
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#: fill circle
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rr, cc = circle(200, 200, 100, img.shape)
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img[rr,cc,:] = (255, 255, 0)
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#: fill ellipse
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rr, cc = ellipse(300, 300, 100, 200, img.shape)
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img[rr,cc,2] = 255
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plt.imshow(img)
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plt.show()
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+131
-7
@@ -1,16 +1,20 @@
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import numpy as np
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import math
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from libc.math cimport sqrt
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cimport numpy as np
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cimport cython
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cdef extern from "math.h":
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int abs(int i)
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cdef extern from "../morphology/_pnpoly.h":
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int pnpoly(int nr_verts, double *xp, double *yp,
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double x, double y)
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@cython.boundscheck(False)
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@cython.wraparound(False)
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def bresenham(int y, int x, int y2, int x2):
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"""
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Generate line pixel coordinates.
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def line(int y, int x, int y2, int x2):
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"""Generate line pixel coordinates.
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Parameters
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----------
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y, x : int
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@@ -46,7 +50,7 @@ def bresenham(int y, int x, int y2, int x2):
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rr = np.zeros(int(dx) + 1, dtype=np.int32)
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cc = np.zeros(int(dx) + 1, dtype=np.int32)
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for i in range(dx):
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if steep:
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rr[i] = x
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@@ -64,3 +68,123 @@ def bresenham(int y, int x, int y2, int x2):
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cc[dx] = x2
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return rr, cc
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@cython.boundscheck(False)
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@cython.wraparound(False)
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@cython.nonecheck(False)
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def polygon(y, x, shape=None):
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"""Generate coordinates of pixels within polygon.
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Parameters
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----------
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y : (N,) ndarray
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y coordinates of vertices of polygon
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x : (N,) ndarray
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x coordinates of vertices of polygon
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shape : tuple, optional
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image shape which is used to determine maximum extents of output pixel
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coordinates. This is useful for polygons which exceed the image size.
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By default the full extents of the polygon are used.
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Returns
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-------
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rr, cc : ndarray of int
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Pixel coordinates of polygon.
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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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"""
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cdef int nr_verts = x.shape[0]
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cdef int minr = <int>max(0, y.min())
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cdef int maxr = <int>math.ceil(y.max())
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cdef int minc = <int>max(0, x.min())
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cdef int maxc = <int>math.ceil(x.max())
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# make sure output coordinates do not exceed image size
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if shape is not None:
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maxr = min(shape[0]-1, maxr)
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maxc = min(shape[1]-1, maxc)
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cdef int r, c
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#: make contigous arrays for r, c coordinates
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cdef np.ndarray contiguous_rdata, contiguous_cdata
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contiguous_rdata = np.ascontiguousarray(y, 'double')
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contiguous_cdata = np.ascontiguousarray(x, 'double')
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cdef np.double_t* rptr = <np.double_t*>contiguous_rdata.data
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cdef np.double_t* cptr = <np.double_t*>contiguous_cdata.data
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#: output coordinate arrays
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cdef list rr = list()
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cdef list cc = list()
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for r in range(minr, maxr+1):
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for c in range(minc, maxc+1):
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if pnpoly(nr_verts, cptr, rptr, c, r):
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rr.append(r)
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cc.append(c)
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return np.array(rr), np.array(cc)
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@cython.boundscheck(False)
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@cython.wraparound(False)
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@cython.nonecheck(False)
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@cython.cdivision(True)
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def ellipse(double cy, double cx, double b, double a, shape=None):
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"""Generate coordinates of pixels within ellipse.
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Parameters
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----------
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cy, cx : double
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centre coordinate of ellipse
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b, a: double
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minor and major semi-axes. (x/a)**2 + (y/b)**2 = 1
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Returns
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-------
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rr, cc : ndarray of int
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Pixel coordinates of ellipse.
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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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"""
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cdef int minr = <int>max(0, cy-b)
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cdef int maxr = <int>math.ceil(cy+b)
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cdef int minc = <int>max(0, cx-a)
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cdef int maxc = <int>math.ceil(cx+a)
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# make sure output coordinates do not exceed image size
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if shape is not None:
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maxr = min(shape[0]-1, maxr)
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maxc = min(shape[1]-1, maxc)
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cdef int r, c
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#: output coordinate arrays
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cdef list rr = list()
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cdef list cc = list()
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for r in range(minr, maxr+1):
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for c in range(minc, maxc+1):
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if sqrt(((r - cy)/b)**2 + ((c - cx)/a)**2) < 1:
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rr.append(r)
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cc.append(c)
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return np.array(rr), np.array(cc)
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def circle(double cy, double cx, double radius, shape=None):
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"""Generate coordinates of pixels within circle.
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Parameters
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----------
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cy, cx : double
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centre coordinate of circle
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radius: double
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radius of circle
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Returns
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-------
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rr, cc : ndarray of int
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Pixel coordinates of ellipse.
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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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"""
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return ellipse(cy, cx, radius, radius, shape)
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@@ -3,4 +3,4 @@ Methods to draw on arrays.
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"""
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from ._draw import bresenham
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from ._draw import line, polygon, ellipse, circle
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+132
-10
@@ -1,12 +1,13 @@
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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 bresenham
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from skimage.draw import line, polygon, circle, ellipse
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def test_bresenham_horizontal():
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def test_line_horizontal():
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img = np.zeros((10, 10))
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rr, cc = bresenham(0, 0, 0, 9)
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rr, cc = line(0, 0, 0, 9)
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img[rr, cc] = 1
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img_ = np.zeros((10, 10))
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@@ -14,10 +15,10 @@ def test_bresenham_horizontal():
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assert_array_equal(img, img_)
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def test_bresenham_vertical():
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def test_line_vertical():
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img = np.zeros((10, 10))
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rr, cc = bresenham(0, 0, 9, 0)
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rr, cc = line(0, 0, 9, 0)
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img[rr, cc] = 1
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img_ = np.zeros((10, 10))
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@@ -25,10 +26,10 @@ def test_bresenham_vertical():
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assert_array_equal(img, img_)
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def test_reverse():
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def test_line_reverse():
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img = np.zeros((10, 10))
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rr, cc = bresenham(0, 9, 0, 0)
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rr, cc = line(0, 9, 0, 0)
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img[rr, cc] = 1
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img_ = np.zeros((10, 10))
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@@ -36,10 +37,10 @@ def test_reverse():
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assert_array_equal(img, img_)
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def test_diag():
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def test_line_diag():
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img = np.zeros((5, 5))
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rr, cc = bresenham(0, 0, 4, 4)
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rr, cc = line(0, 0, 4, 4)
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img[rr, cc] = 1
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img_ = np.eye(5)
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@@ -47,6 +48,127 @@ def test_diag():
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assert_array_equal(img, img_)
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def test_polygon_rectangle():
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img = np.zeros((10, 10), 'uint8')
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poly = np.array(((1, 1), (4, 1), (4, 4), (1, 4), (1, 1)))
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rr, cc = polygon(poly[:,0], poly[:,1])
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img[rr,cc] = 1
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img_ = np.zeros((10, 10))
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img_[1:4,1:4] = 1
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assert_array_equal(img, img_)
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def test_polygon_rectangle_angular():
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img = np.zeros((10, 10), 'uint8')
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poly = np.array(((0, 3), (4, 7), (7, 4), (3, 0), (0, 3)))
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rr, cc = polygon(poly[:,0], poly[:,1])
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img[rr,cc] = 1
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img_ = np.array(
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[[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
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[0, 0, 1, 1, 0, 0, 0, 0, 0, 0],
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[0, 1, 1, 1, 1, 0, 0, 0, 0, 0],
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[1, 1, 1, 1, 1, 1, 0, 0, 0, 0],
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[0, 1, 1, 1, 1, 1, 1, 0, 0, 0],
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[0, 0, 1, 1, 1, 1, 0, 0, 0, 0],
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[0, 0, 0, 1, 1, 0, 0, 0, 0, 0],
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[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
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[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
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[0, 0, 0, 0, 0, 0, 0, 0, 0, 0]]
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)
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assert_array_equal(img, img_)
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def test_polygon_parallelogram():
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img = np.zeros((10, 10), 'uint8')
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poly = np.array(((1, 1), (5, 1), (7, 6), (3, 6), (1, 1)))
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rr, cc = polygon(poly[:,0], poly[:,1])
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img[rr,cc] = 1
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img_ = np.array(
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[[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
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[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
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[0, 1, 1, 1, 0, 0, 0, 0, 0, 0],
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[0, 1, 1, 1, 1, 1, 0, 0, 0, 0],
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[0, 1, 1, 1, 1, 1, 0, 0, 0, 0],
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[0, 1, 1, 1, 1, 1, 0, 0, 0, 0],
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[0, 0, 0, 0, 1, 1, 0, 0, 0, 0],
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[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
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[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
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[0, 0, 0, 0, 0, 0, 0, 0, 0, 0]]
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)
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assert_array_equal(img, img_)
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def test_polygon_exceed():
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img = np.zeros((10, 10), 'uint8')
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poly = np.array(((1, -1), (100, -1), (100, 100), (1, 100), (1, 1)))
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rr, cc = polygon(poly[:,0], poly[:,1], img.shape)
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img[rr,cc] = 1
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img_ = np.zeros((10, 10))
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img_[1:,:] = 1
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assert_array_equal(img, img_)
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def test_circle():
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img = np.zeros((15, 15), 'uint8')
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rr, cc = circle(7, 7, 6)
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img[rr,cc] = 1
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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, 0, 0, 0, 0, 0, 0, 0, 0, 0],
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[0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0],
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[0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0],
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[0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0],
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[0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0],
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[0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0],
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[0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0],
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[0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0],
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[0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0],
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[0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0],
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[0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0],
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[0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0],
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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, 0, 0, 0, 0, 0, 0, 0, 0, 0]]
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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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rr, cc = ellipse(7, 7, 3, 7)
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img[rr,cc] = 1
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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, 0, 0, 0, 0, 0, 0, 0, 0, 0],
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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, 0, 0, 0, 0, 0, 0, 0, 0, 0],
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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, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0],
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[0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0],
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[0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0],
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[0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0],
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[0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0],
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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, 0, 0, 0, 0, 0, 0, 0, 0, 0],
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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, 0, 0, 0, 0, 0, 0, 0, 0, 0],
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[0, 0, 0, 0, 0, 0, 0, 0, 0, 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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run_module_suite()
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