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Tighten up _find_contours.pyx

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Remove some redundant operations in _find_contours.pyx -- will speed
things especially in common case where most pixels DON'T have a contour
nearby.
This commit is contained in:
Zach Pincus
2011-12-01 12:34:08 -05:00
parent 60abf40c39
commit fbb07734fc
1 changed files with 86 additions and 85 deletions
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skimage/measure/_find_contours.pyx
+86 -85
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@@ -6,7 +6,8 @@ cimport numpy as np
np.import_array()
cdef double _get_fraction(double from_value, double to_value, double level):
cdef inline double _get_fraction(double from_value, double to_value,
double level):
if (to_value == from_value):
return 0
return ((level - from_value) / (to_value - from_value))
@@ -70,7 +71,7 @@ def iterate_and_store(np.ndarray[double, ndim=2, mode='c'] array,
# cases 6 and 9. In this case, where the segments are placed
# is determined by vertex_connect_high. If
# vertex_connect_high is false, then lines like \\ are drawn
# through square 6, and lines like # are drawn through square
# through square 6, and lines like // are drawn through square
# 9. Otherwise, the situation is reversed.
# Finally, recall that we draw the lines so that (moving from tail to
# head) the lower-valued pixels are on the left of the line. So, for
@@ -81,9 +82,17 @@ def iterate_and_store(np.ndarray[double, ndim=2, mode='c'] array,
r1, c1 = r0 + 1, c0 + 1
ul = array[r0, c0]
ur = array[r0, c0 + 1]
ll = array[r0 + 1, c0]
lr = array[r0 + 1, c0 + 1]
ur = array[r0, c1]
ll = array[r1, c0]
lr = array[r1, c1]
# now in advance the coords indices
if coords[1] < array.shape[1] - 2:
coords[1] += 1
else:
coords[0] += 1
coords[1] = 0
square_case = 0
if (ul > level): square_case += 1
@@ -91,95 +100,87 @@ def iterate_and_store(np.ndarray[double, ndim=2, mode='c'] array,
if (ll > level): square_case += 4
if (lr > level): square_case += 8
top = coords[0], coords[1] + _get_fraction(ul, ur, level)
bottom = coords[0] + 1, coords[1] + _get_fraction(ll, lr, level)
left = coords[0] + _get_fraction(ul, ll, level), coords[1]
right = coords[0] + _get_fraction(ur, lr, level), coords[1] + 1
if (square_case != 0 and square_case != 15):
# only do anything if there's a line passing through the
# square. Cases 0 and 15 are entirely below/above the contour.
top = r0, c0 + _get_fraction(ul, ur, level)
bottom = r1, c0 + _get_fraction(ll, lr, level)
left = r0 + _get_fraction(ul, ll, level), c0
right = r0 + _get_fraction(ur, lr, level), c1
if (square_case == 0):
# no line
pass
elif (square_case == 1):
# top to left
arc_list.append(top)
arc_list.append(left)
elif (square_case == 2):
# right to top
arc_list.append(right)
arc_list.append(top)
elif (square_case == 3):
# right to left
arc_list.append(right)
arc_list.append(left)
elif (square_case == 4):
# left to bottom
arc_list.append(left)
arc_list.append(bottom)
elif (square_case == 5):
# top to bottom
arc_list.append(top)
arc_list.append(bottom)
elif (square_case == 6):
if vertex_connect_high:
arc_list.append(left)
arc_list.append(top)
arc_list.append(right)
arc_list.append(bottom)
else:
arc_list.append(right)
if (square_case == 1):
# top to left
arc_list.append(top)
arc_list.append(left)
arc_list.append(bottom)
elif (square_case == 7):
# right to bottom
arc_list.append(right)
arc_list.append(bottom)
elif (square_case == 8):
# bottom to right
arc_list.append(bottom)
arc_list.append(right)
elif (square_case == 9):
if vertex_connect_high:
arc_list.append(top)
elif (square_case == 2):
# right to top
arc_list.append(right)
arc_list.append(bottom)
arc_list.append(left)
else:
arc_list.append(top)
elif (square_case == 3):
# right to left
arc_list.append(right)
arc_list.append(left)
elif (square_case == 4):
# left to bottom
arc_list.append(left)
arc_list.append(bottom)
elif (square_case == 5):
# top to bottom
arc_list.append(top)
arc_list.append(bottom)
elif (square_case == 6):
if vertex_connect_high:
arc_list.append(left)
arc_list.append(top)
arc_list.append(right)
arc_list.append(bottom)
else:
arc_list.append(right)
arc_list.append(top)
arc_list.append(left)
arc_list.append(bottom)
elif (square_case == 7):
# right to bottom
arc_list.append(right)
arc_list.append(bottom)
elif (square_case == 8):
# bottom to right
arc_list.append(bottom)
arc_list.append(right)
elif (square_case == 10):
# bottom to top
arc_list.append(bottom)
arc_list.append(top)
elif (square_case == 11):
# bottom to left
arc_list.append(bottom)
arc_list.append(left)
elif (square_case == 12):
# lef to right
arc_list.append(left)
arc_list.append(right)
elif (square_case == 13):
# top to right
arc_list.append(top)
arc_list.append(right)
elif (square_case == 14):
# left to top
arc_list.append(left)
arc_list.append(top)
elif (square_case == 15):
# no line
pass
elif (square_case == 9):
if vertex_connect_high:
arc_list.append(top)
arc_list.append(right)
if coords[1] < array.shape[1] - 2:
coords[1] += 1
else:
coords[0] += 1
coords[1] = 0
arc_list.append(bottom)
arc_list.append(left)
else:
arc_list.append(top)
arc_list.append(left)
arc_list.append(bottom)
arc_list.append(right)
elif (square_case == 10):
# bottom to top
arc_list.append(bottom)
arc_list.append(top)
elif (square_case == 11):
# bottom to left
arc_list.append(bottom)
arc_list.append(left)
elif (square_case == 12):
# lef to right
arc_list.append(left)
arc_list.append(right)
elif (square_case == 13):
# top to right
arc_list.append(top)
arc_list.append(right)
elif (square_case == 14):
# left to top
arc_list.append(left)
arc_list.append(top)
return arc_list