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Speed up memory views in local_binary_pattern

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This commit is contained in:
Johannes Schönberger
2013-10-18 20:49:49 +02:00
parent 354c8502c2
commit bfb0cfce2f
1 changed files with 11 additions and 11 deletions
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skimage/feature/_texture.pyx
+11 -11
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@@ -106,17 +106,17 @@ def _local_binary_pattern(double[:, ::1] image,
"""
# texture weights
cdef int[:] weights = 2 ** np.arange(P, dtype=np.int32)
cdef int[::1] weights = 2 ** np.arange(P, dtype=np.int32)
# local position of texture elements
rr = - R * np.sin(2 * np.pi * np.arange(P, dtype=np.double) / P)
cc = R * np.cos(2 * np.pi * np.arange(P, dtype=np.double) / P)
cdef double[:] rp = np.round(rr, 5)
cdef double[:] cp = np.round(cc, 5)
cdef double[::1] rp = np.round(rr, 5)
cdef double[::1] cp = np.round(cc, 5)
# pre-allocate arrays for computation
cdef double[:] texture = np.zeros(P, dtype=np.double)
cdef char[:] signed_texture = np.zeros(P, dtype=np.int8)
cdef int[:] rotation_chain = np.zeros(P, dtype=np.int32)
cdef double[::1] texture = np.zeros(P, dtype=np.double)
cdef char[::1] signed_texture = np.zeros(P, dtype=np.int8)
cdef int[::1] rotation_chain = np.zeros(P, dtype=np.int32)
output_shape = (image.shape[0], image.shape[1])
cdef double[:, ::1] output = np.zeros(output_shape, dtype=np.double)
@@ -162,21 +162,21 @@ def _local_binary_pattern(double[:, ::1] image,
# n_ones=2: 0011, 1001, 1100, 0110
# n_ones=3: 0111, 1011, 1101, 1110
# n_ones=4: 1111
#
#
# For a pattern of size P there are 2 constant patterns
# corresponding to n_ones=0 and n_ones=P. For each other
# value of `n_ones` , i.e n_ones=[1..P-1], there are P
# possible patterns which are related to each other through
# circular permutations. The total number of uniform
# patterns is thus (2 + P * (P - 1)).
# patterns is thus (2 + P * (P - 1)).
# Given any pattern (uniform or not) we must be able to
# associate a unique code:
# associate a unique code:
# 1. Constant patterns patterns (with n_ones=0 and
# n_ones=P) and non uniform patterns are given fixed
# code values.
# 2. Other uniform patterns are indexed considering the
# value of n_ones, and an index called 'rot_index'
# reprenting the number of circular right shifts
# reprenting the number of circular right shifts
# required to obtain the pattern starting from a
# reference position (corresponding to all zeros stacked
# on the right). This number of rotations (or circular
@@ -215,7 +215,7 @@ def _local_binary_pattern(double[:, ::1] image,
lbp += signed_texture[i]
else:
lbp = P + 1
if method == 'V':
var = np.var(texture)
if var != 0: