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Speeding up corner_fast_orientation

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This commit is contained in:
Ankit Agrawal
2013-08-26 18:51:08 +05:30
committed by Johannes Schönberger
parent 3b76623a68
commit b2bf0baad8
1 changed files with 14 additions and 13 deletions
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skimage/feature/corner_cy.pyx
+14 -13
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@@ -200,13 +200,13 @@ def corner_fast_orientation(image, fast_corners):
raise ValueError("Only 2-D gray-scale images supported.")
# Essentially skimage.morphology.octagon(3, 2)
circular_mask = np.array([[0, 0, 1, 1, 1, 0, 0],
[0, 1, 1, 1, 1, 1, 0],
[1, 1, 1, 1, 1, 1, 1],
[1, 1, 1, 1, 1, 1, 1],
[1, 1, 1, 1, 1, 1, 1],
[0, 1, 1, 1, 1, 1, 0],
[0, 0, 1, 1, 1, 0, 0]], dtype=np.uint8)
cdef char[:, :] circular_mask = np.array([[0, 0, 1, 1, 1, 0, 0],
[0, 1, 1, 1, 1, 1, 0],
[1, 1, 1, 1, 1, 1, 1],
[1, 1, 1, 1, 1, 1, 1],
[1, 1, 1, 1, 1, 1, 1],
[0, 1, 1, 1, 1, 1, 0],
[0, 0, 1, 1, 1, 0, 0]], dtype=np.uint8)
cdef Py_ssize_t[:, :] cfast_corners = np.ascontiguousarray(fast_corners, dtype=np.intp)
@@ -219,13 +219,14 @@ def corner_fast_orientation(image, fast_corners):
x = cfast_corners[i, 0]
y = cfast_corners[i, 1]
kp_circular_patch = image[x - 3:x + 4, y - 3:y + 4] * circular_mask
kp_circular_patch = np.ascontiguousarray(image[x - 3:x + 4, y - 3:y + 4])
mu = np.zeros((2, 2), dtype=np.double)
for p in range(2):
for q in range(2):
for r in range(7):
for c in range(7):
mu[p, q] += kp_circular_patch[r, c] * (r - 3) ** q * (c - 3) ** p
for r in range(7):
for c in range(7):
if circular_mask[r, c]:
for p in range(2):
for q in range(2):
mu[p, q] += kp_circular_patch[r, c] * (r - 3) ** q * (c - 3) ** p
kp_orientation[i] = atan2(mu[1, 0] / mu[0, 0], mu[0, 1] / mu[0, 0])