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Speeding up corner_fast_implementation : 2

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Ankit Agrawal
2013-11-29 20:42:04 +01:00
committed by Johannes Schönberger
parent b2bf0baad8
commit 84317b6a2f
2 changed files with 37 additions and 24 deletions
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skimage/feature/corner_cy.pyx
+30 -19
View File
@@ -167,7 +167,7 @@ def _corner_fast(double[:, ::1] image, char n, double threshold):
return np.asarray(corner_response)
def corner_fast_orientation(image, fast_corners):
def corner_fast_orientation(image, Py_ssize_t[:, :] fast_corners):
"""Compute the orientation of FAST corners using the first order central
moment i.e. the center of mass approach. The corner orientation is the
angle of the vector from the keypoint to the intensity centroid calculated
@@ -199,35 +199,46 @@ def corner_fast_orientation(image, fast_corners):
if image.ndim != 2:
raise ValueError("Only 2-D gray-scale images supported.")
cdef double[:, :] cimage = np.ascontiguousarray(img_as_float(image))
# Essentially skimage.morphology.octagon(3, 2)
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)
cdef char[:, ::1] 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 n_fast_corners = fast_corners.shape[0]
cdef Py_ssize_t i, p, q, r, c, x, y
cdef Py_ssize_t i, r, c, x_top, y_left
cdef double[:, ::1] kp_circular_patch, mu
cdef double[:] kp_orientation = np.zeros(fast_corners.shape[0], dtype=np.double)
cdef double m00, m01, m10
for i in range(n_fast_corners):
x = cfast_corners[i, 0]
y = cfast_corners[i, 1]
x_top = fast_corners[i, 0] - 3
y_left = fast_corners[i, 1] - 3
kp_circular_patch = np.ascontiguousarray(image[x - 3:x + 4, y - 3:y + 4])
mu = np.zeros((2, 2), dtype=np.double)
m00 = 0
m01 = 0
m10 = 0
#kp_circular_patch = np.ascontiguousarray(image[x - 3:x + 4, y - 3:y + 4])
#mu = np.zeros((2, 2), dtype=np.double)
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
m00 += cimage[x_top + r, y_left + c]
kp_orientation[i] = atan2(mu[1, 0] / mu[0, 0], mu[0, 1] / mu[0, 0])
for r in range(7):
for c in range(7):
if circular_mask[r, c]:
m01 += cimage[x_top + r, y_left + c] * (c - 3)
for r in range(7):
for c in range(7):
if circular_mask[r, c]:
m10 += cimage[x_top + r, y_left + c] * (r - 3)
kp_orientation[i] = atan2(m10 / m00, m01 / m00)
return np.asarray(kp_orientation)
skimage/feature/tests/test_corner.py
+7 -5
View File
@@ -1,5 +1,6 @@
import numpy as np
from numpy.testing import assert_array_equal, assert_almost_equal
from numpy.testing import (assert_array_equal, assert_raises,
assert_almost_equal)
from skimage import data
from skimage import img_as_float
@@ -181,16 +182,17 @@ def test_corner_fast_lena():
def test_corner_fast_orientation_image_unsupported_error():
img = np.zeros((20, 20, 3))
assert_raises(ValueError, corner_fast_orientation, img, [[7, 7]])
assert_raises(ValueError, corner_fast_orientation, img,
np.asarray([[7, 7]]))
def test_corner_fast_orientation_lena():
img = rgb2gray(data.lena())
corners = corner_peaks(corner_fast(img, 11, 0.35))
expected = np.array([-2.79279928, -1.68079274, 2.63070795, -1.81665159,
-2.09631254, -1.41580527])
expected = np.array([-1.9195897 , -3.03159624, -1.05991162, -2.89573739,
-2.61607644, 2.98660159])
actual = corner_fast_orientation(img, corners)
assert_array_equal(actual, expected)
assert_almost_equal(actual, expected)
if __name__ == '__main__':