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Added non rotation invariant local binary patterns

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Alexis Mignon
2013-08-22 15:05:22 +02:00
parent 8d0f91724f
commit 22873b803f
2 changed files with 62 additions and 13 deletions
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skimage/feature/_texture.pyx
+59 -13
View File
@@ -90,12 +90,13 @@ def _local_binary_pattern(double[:, ::1] image,
the angular space).
R : float
Radius of circle (spatial resolution of the operator).
method : {'D', 'R', 'U', 'V'}
method : {'D', 'R', 'U', 'N', 'V'}
Method to determine the pattern.
* 'D': 'default'
* 'R': 'ror'
* 'U': 'uniform'
* 'N': 'nri_uniform'
* 'V': 'var'
Returns
@@ -125,6 +126,9 @@ def _local_binary_pattern(double[:, ::1] image,
cdef double lbp
cdef Py_ssize_t r, c, changes, i
cdef Py_ssize_t r, c, changes, i, rot_index, n_ones
cdef cnp.int8_t first_zero, first_one
for r in range(image.shape[0]):
for c in range(image.shape[1]):
for i in range(P):
@@ -146,19 +150,61 @@ def _local_binary_pattern(double[:, ::1] image,
changes = 0
for i in range(P - 1):
changes += abs(signed_texture[i] - signed_texture[i + 1])
if changes <= 2:
for i in range(P):
lbp += signed_texture[i]
else:
lbp = P + 1
if method == 'V':
var = np.var(texture)
if var != 0:
lbp /= var
if method == 'N':
# Non rotation invariant LBP.
# for P there are P + 1 ror and uniform patterns
# ex: P = 4
# 1: 0 0 0 0
# 2: 0 0 0 1 -> 0 0 1 0, 0 1 0 0, 1 0 0 0
# 3: 0 0 1 1 -> 0 1 1 0, 1 1 0 0, 1 0 0 1
# 4: 0 1 1 1 -> 1 1 1 0, 1 1 0 1, 1 0 1 1
# 5: 1 1 1 1
# The first and last patterns are always invariant under
# rotation. The (P - 1) remaining patterns have P rotated
# variants hence we have P * (P - 1) + 2 uniform patterns
# to which we add the non uniform pattern.
if changes <= 2:
# We have a uniform pattern
n_ones = 0 # determies the number of ones
first_one = -1 # position was the first one
first_zero = -1 # position of the first zero
for i in range(P):
if signed_texture[i]:
n_ones += 1
if first_one == -1:
first_one = i
else:
if first_zero == -1:
first_zero = i
if n_ones == 0:
lbp = 0
elif n_ones == P:
lbp = P * (P - 1) + 1
else:
# There are (P - n_ones) patterns starting with 0.
# This patterns are indexed starting from the
# position where all zeros are on the right and
# applying circular right shifts.
if first_zero == 0:
var_index = P - n_ones - first_one
else:
var_index = P - first_zero
lbp = 1 + (n_ones - 1) * P + var_index
else: # changes > 2
lbp = P * (P - 1) + 2
else: # method != 'N'
if changes <= 2:
for i in range(P):
lbp += signed_texture[i]
else:
lbp = np.nan
lbp = P + 1
if method == 'V':
var = np.var(texture)
if var != 0:
lbp /= var
else:
lbp = np.nan
else:
# method == 'default'
for i in range(P):
skimage/feature/texture.py
+3
View File
@@ -248,6 +248,8 @@ def local_binary_pattern(image, P, R, method='default'):
* 'uniform': improved rotation invariance with uniform patterns and
finer quantization of the angular space which is gray scale and
rotation invariant.
* 'nri_uniform': non rotation-invariant uniform patterns variant
which is only gray scale invariant.
* 'var': rotation invariant variance measures of the contrast of local
image texture which is rotation but not gray scale invariant.
@@ -269,6 +271,7 @@ def local_binary_pattern(image, P, R, method='default'):
'default': ord('D'),
'ror': ord('R'),
'uniform': ord('U'),
'nri_uniform': ord('N'),
'var': ord('V')
}
image = np.ascontiguousarray(image, dtype=np.double)