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iradon_sart: Reduce code duplication in interpolation.

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Jostein Bø Fløystad
2013-06-10 22:13:43 +02:00
parent 91aeb658dd
commit 5baaf78564
1 changed files with 16 additions and 10 deletions
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skimage/transform/_radon_transform.pyx
+16 -10
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@@ -40,10 +40,12 @@ cpdef bilinear_ray_sum(cnp.double_t[:, :] image, cnp.double_t theta,
# s0 is the half-length of the ray's path in the reconstruction circle
cdef cnp.double_t s0
s0 = sqrt(radius**2 - t**2) if radius**2 >= t**2 else 0.
cdef Py_ssize_t Ns = 2 * (<Py_ssize_t> ceil(2 * s0)) # number of steps along the ray
cdef Py_ssize_t Ns = 2 * (<Py_ssize_t> ceil(2 * s0)) # number of steps
# along the ray
cdef cnp.double_t ray_sum = 0.
cdef cnp.double_t weight_norm = 0.
cdef cnp.double_t ds, dx, dy, x0, y0, x, y, di, dj, index_i, index_j
cdef cnp.double_t ds, dx, dy, x0, y0, x, y, di, dj,
cdef cnp.double_t index_i, index_j, weight
cdef Py_ssize_t k, i, j
if Ns > 0:
# step length between samples
@@ -65,17 +67,21 @@ cpdef bilinear_ray_sum(cnp.double_t[:, :] image, cnp.double_t theta,
# Use linear interpolation between values
# Where values fall outside the array, assume zero
if i > 0 and j > 0:
ray_sum += (1. - di) * (1. - dj) * image[i, j] * ds
weight_norm += ((1 - di) * (1 - dj) * ds)**2
weight = (1. - di) * (1. - dj) * ds
ray_sum += weight * image[i, j]
weight_norm += weight**2
if i > 0 and j < image.shape[1] - 1:
ray_sum += (1. - di) * dj * image[i, j+1] * ds
weight_norm += ((1 - di) * dj * ds)**2
weight = (1. - di) * dj * ds
ray_sum += weight * image[i, j+1]
weight_norm += weight**2
if i < image.shape[0] - 1 and j > 0:
ray_sum += di * (1 - dj) * image[i+1, j] * ds
weight_norm += (di * (1 - dj) * ds)**2
weight = di * (1 - dj) * ds
ray_sum += weight * image[i+1, j]
weight_norm += weight**2
if i < image.shape[0] - 1 and j < image.shape[1] - 1:
ray_sum += di * dj * image[i+1, j+1] * ds
weight_norm += (di * dj * ds)**2
weight = di * dj * ds
ray_sum += weight * image[i+1, j+1]
weight_norm += weight**2
return ray_sum, weight_norm