Commit c5b4ef7c authored by Richard Torenvliet's avatar Richard Torenvliet

Merge branch 'master' of github.com:taddeus/licenseplates

Conflicts:
	docs/report.tex
parents 6dbb4aa6 2e1b2e8c
......@@ -15,9 +15,3 @@ images/BBB
images/Images
images/Infos
images/licenseplates
chars
learning_set
test_set
classifier
classifier-model
classifier-characters
......@@ -45,10 +45,8 @@ in classifying characters on a license plate.
In short our program must be able to do the following:
\begin{enumerate}
\item Use a perspective transformation to obtain an upfront view of license
plate.
\item Reduce noise where possible to ensure maximum readability.
\item Extracting characters using the location points in the xml file.
\item Reduce noise where possible to ensure maximum readability.
\item Transforming a character to a normal form.
\item Creating a local binary pattern histogram vector.
\item Matching the found vector with a learning set.
......@@ -60,7 +58,7 @@ In short our program must be able to do the following:
The actual purpose of this project is to check if LBP is capable of recognizing
license plate characters. We knew the LBP implementation would be pretty
simple. Thus an advantage had to be its speed compared with other license plate
recognition implementations, but the uncertainity of whether we could get some
recognition implementations, but the uncertainty of whether we could get some
results made us pick Python. We felt Python would not restrict us as much in
assigning tasks to each member of the group. In addition, when using the
correct modules to handle images, Python can be decent in speed.
......@@ -70,48 +68,46 @@ correct modules to handle images, Python can be decent in speed.
Now we know what our program has to be capable of, we can start with the
implementations.
\subsection{Extracting a letter}
Rewrite this section once we have implemented this properly.
%NO LONGER VALID!
%Because we are already given the locations of the characters, we only need to
%transform those locations using the same perspective transformation used to
%create a front facing license plate. The next step is to transform the
%characters to a normalized manner. The size of the letter W is used as a
%standard to normalize the width of all the characters, because W is the widest
%character of the alphabet. We plan to also normalize the height of characters,
%the best manner for this is still to be determined.
%\begin{enumerate}
% \item Crop the image in such a way that the character precisely fits the
% image.
% \item Scale the image to a standard height.
% \item Extend the image on either the left or right side to a certain width.
%\end{enumerate}
%The resulting image will always have the same size, the character contained
%will always be of the same height, and the character will always be positioned
%at either the left of right side of the image.
\subsection{Transformation}
A simple perspective transformation will be sufficient to transform and resize
the plate to a normalized format. The corner positions of license plates in the
the characters to a normalized format. The corner positions of characters in the
dataset are supplied together with the dataset.
\subsection{Extracting a letter}
NO LONGER VALID!
Because we are already given the locations of the characters, we only need to
transform those locations using the same perspective transformation used to
create a front facing license plate. The next step is to transform the
characters to a normalized manner. The size of the letter W is used as a
standard to normalize the width of all the characters, because W is the widest
character of the alphabet. We plan to also normalize the height of characters,
the best manner for this is still to be determined.
\begin{enumerate}
\item Crop the image in such a way that the character precisely fits the
image.
\item Scale the image to a standard height.
\item Extend the image on either the left or right side to a certain width.
\end{enumerate}
The resulting image will always have the same size, the character contained
will always be of the same height, and the character will alway be positioned
at either the left of right side of the image.
\subsection{Reducing noise}
Small amounts of noise will probably be suppressed by usage of a Gaussian
filter. A real problem occurs in very dirty license plates, where branches and
dirt over a letter could radically change the local binary pattern. A question
we can ask ourselves here, is whether we want to concentrate ourselves on these
exceptional cases. By law, license plates have to be readable. Therefore, we
will first direct our attention at getting a higher score in the 'regular' test
set before addressing these cases. Considered the fact that the LBP algorithm
divides a letter into a lot of cells, there is a good change that a great
number of cells will still match the learning set, and thus still return the
correct character as a best match. Therefore, we expect the algorithm to be
very robust when dealing with noisy images.
exceptional cases. By law, license plates have to be readable. However, the
provided dataset showed that this does not means they always are. We will have
to see how the algorithm performs on these plates, however we have good hopes
that our method will get a good score on dirty plates, as long as a big enough
part of the license plate remains readable.
\subsection{Local binary patterns}
Once we have separate digits and characters, we intent to use Local Binary
......@@ -128,9 +124,9 @@ form where the pattern is circular.
\begin{itemize}
\item Determine the size of the square where the local patterns are being
registered. For explanation purposes let the square be 3 x 3. \\
\item The grayscale value of the middle pixel is used a threshold. Every value
of the pixel around the middle pixel is evaluated. If it's value is greater
than the threshold it will be become a one else a zero.
\item The grayscale value of the middle pixel is used as threshold. Every
value of the pixel around the middle pixel is evaluated. If it's value is
greater than the threshold it will be become a one else a zero.
\begin{figure}[h!]
\center
......@@ -176,27 +172,29 @@ order. Starting with dividing the pattern in to cells of size 16.
result is a feature vector of the image.
\item Feed these vectors to a support vector machine. This will ''learn'' which
<<<<<<< HEAD
vector indicates what vector is which character.
=======
vectors indicate what letter.
>>>>>>> 2e1b2e8c8db4f802d203791a6f03eeca7d0aff70
\end{itemize}
To our knowledge, LBP has yet not been used in this manner before. Therefore,
it will be the first thing to implement, to see if it lives up to the
expectations. When the proof of concept is there, it can be used in the final
expectations. When the proof of concept is there, it can be used in a final
program.
Important to note is that due to the normalization of characters before
applying LBP. Therefore, no further normalization is needed on the histograms.
Given the LBP of a character, a Support Vector Machine can be used to classify
the character to a character in a learning set. The SVM uses
Later we will show that taking a histogram over the entire image (basically
working with just one cell) gives us the best results.
\subsection{Matching the database}
Given the LBP of a character, a Support Vector Machine can be used to classify
the character to a character in a learning set. The SVM uses the collection of
histograms of an image as a feature vector. The SVM can be trained with a
subsection of the given dataset called the ''Learning set''. Once trained, the
the character to a character in a learning set. The SVM uses a concatenation
of each cell in an image as a feature vector (in the case we check the entire
image no concatenation has to be done of course. The SVM can be trained with a
subset of the given dataset called the ''Learning set''. Once trained, the
entire classifier can be saved as a Pickle object\footnote{See
\url{http://docs.python.org/library/pickle.html}} for later usage.
......@@ -205,11 +203,11 @@ entire classifier can be saved as a Pickle object\footnote{See
In this section we will describe our implementations in more detail, explaining
choices we made.
\subsection{Licenseplate retrieval}
\subsection{Character retrieval}
In order to retrieve the license plate from the entire image, we need to
In order to retrieve the characters from the entire image, we need to
perform a perspective transformation. However, to do this, we need to know the
coordinates of the four corners of the licenseplate. For our dataset, this is
coordinates of the four corners of each character. For our dataset, this is
stored in XML files. So, the first step is to read these XML files.
\paragraph*{XML reader}
......@@ -247,9 +245,9 @@ NormalizedImage. When these actions have been completed for each character the
license plate is usable in the rest of the code.
\paragraph*{Perspective transformation}
Once we retrieved the cornerpoints of the license plate, we feed those to a
module that extracts the (warped) license plate from the original image, and
creates a new image where the license plate is cut out, and is transformed to a
Once we retrieved the cornerpoints of the character, we feed those to a
module that extracts the (warped) character from the original image, and
creates a new image where the character is cut out, and is transformed to a
rectangle.
\subsection{Noise reduction}
......@@ -277,13 +275,6 @@ the dirt, and the fact that the characters are very black, the shape of the
characters will still be conserved in the LBP, even if there is dirt
surrounding the character.
\subsection{Character retrieval}
The retrieval of the character is done the same as the retrieval of the license
plate, by using a perspective transformation. The location of the characters on
the license plate is also available in de XML file, so this is parsed from that
as well.
\subsection{Creating Local Binary Patterns and feature vector}
Every pixel is a center pixel and it is also a value to evaluate but not at the
same time. Every pixel is evaluated as shown in the explanation
......@@ -337,9 +328,7 @@ value, and what value we decided on.
The first parameter to decide on, is the $\sigma$ used in the Gaussian blur. To
find this parameter, we tested a few values, by checking visually what value
removed most noise out of the image, while keeping the edges sharp enough to
work with. By checking in the neighbourhood of the value that performed best,
we where able to 'zoom in' on what we thought was the best value. It turned out
that this was $\sigma = ?$.
work with. It turned out the best value is $\sigma = 0.5$.
\subsection{Parameter \emph{cell size}}
......@@ -352,8 +341,9 @@ be enough cells to properly describe the different areas of the character, and
the feature vectors will not have enough elements.\\
\\
In order to find this parameter, we used a trial-and-error technique on a few
basic cell sizes, being ?, 16, ?. We found that the best result was reached by
using ??.
cell sizes. During this testing, we discovered that a lot better score was
reached when we take the histogram over the entire image, so with a single
cell. therefor, we decided to work without cells.
\subsection{Parameters $\gamma$ \& $c$}
......@@ -374,7 +364,8 @@ checks for each combination of values what the score is. The combination with
the highest score is then used as our parameters, and the entire SVM will be
trained using those parameters.\\
\\
We found that the best values for these parameters are $c=?$ and $\gamma =?$.
We found that the best values for these parameters are $c = ?$ and
$\gamma = ?$.
\section{Results}
......
*.dat
results.txt
from LocalBinaryPatternizer import LocalBinaryPatternizer
from LocalBinaryPatternizer import LocalBinaryPatternizer as LBP
class Character:
def __init__(self, value, corners, image, filename=None):
......@@ -7,7 +7,14 @@ class Character:
self.image = image
self.filename = filename
def get_feature_vector(self):
pattern = LocalBinaryPatternizer(self.image)
def get_single_cell_feature_vector(self):
if hasattr(self, 'feature'):
return
self.feature = LBP(self.image).single_cell_features_vector()
def get_feature_vector(self, cell_size=None):
pattern = LBP(self.image) if cell_size == None \
else LBP(self.image, cell_size)
return pattern.create_features_vector()
from svmutil import svm_train, svm_problem, svm_parameter, svm_predict, \
svm_save_model, svm_load_model
svm_save_model, svm_load_model, RBF
class Classifier:
def __init__(self, c=None, gamma=None, filename=None):
def __init__(self, c=None, gamma=None, filename=None, cell_size=12):
self.cell_size = cell_size
if filename:
# If a filename is given, load a model from the given filename
self.model = svm_load_model(filename)
......@@ -11,8 +13,8 @@ class Classifier:
raise Exception('Please specify both C and gamma.')
else:
self.param = svm_parameter()
self.param.kernel_type = 2 # Radial kernel type
self.param.C = c # Soft margin
self.param.kernel_type = RBF # Radial kernel type
self.param.gamma = gamma # Parameter for radial kernel
self.model = None
......@@ -28,10 +30,12 @@ class Classifier:
l = len(learning_set)
for i, char in enumerate(learning_set):
print 'Training "%s" -- %d of %d (%d%% done)' \
print 'Found "%s" -- %d of %d (%d%% done)' \
% (char.value, i + 1, l, int(100 * (i + 1) / l))
classes.append(float(ord(char.value)))
features.append(char.get_feature_vector())
#features.append(char.get_feature_vector())
char.get_single_cell_feature_vector()
features.append(char.feature)
problem = svm_problem(classes, features)
self.model = svm_train(problem, self.param)
......@@ -48,9 +52,12 @@ class Classifier:
return float(matches) / len(test_set)
def classify(self, character):
def classify(self, character, true_value=None):
"""Classify a character object, return its value."""
predict = lambda x: svm_predict([0], [x], self.model)[0][0]
prediction_class = predict(character.get_feature_vector())
true_value = 0 if true_value == None else ord(true_value)
#x = character.get_feature_vector(self.cell_size)
character.get_single_cell_feature_vector()
p = svm_predict([true_value], [character.feature], self.model)
prediction_class = int(p[0][0])
return chr(int(prediction_class))
return chr(prediction_class)
......@@ -18,19 +18,23 @@ class GrayscaleImage:
self.data = data
def __iter__(self):
self.__i_x = -1
self.__i_y = 0
return self
def next(self):
self.__i_x += 1
if self.__i_x == self.width:
self.__i_x = 0
self.__i_y += 1
if self.__i_y == self.height:
raise StopIteration
return self.__i_y, self.__i_x, self[self.__i_y, self.__i_x]
for y in xrange(self.data.shape[0]):
for x in xrange(self.data.shape[1]):
yield y, x, self.data[y, x]
#self.__i_x = -1
#self.__i_y = 0
#return self
#def next(self):
# self.__i_x += 1
# if self.__i_x == self.width:
# self.__i_x = 0
# self.__i_y += 1
# if self.__i_y == self.height:
# raise StopIteration
# return self.__i_y, self.__i_x, self[self.__i_y, self.__i_x]
def __getitem__(self, position):
return self.data[position]
......
......@@ -16,6 +16,12 @@ class Histogram:
def get_bin_index(self, number):
return (number - self.min) / ((self.max - self.min) / len(self.bins))
def normalize(self):
minimum = min(self.bins)
self.bins = map(lambda b: b - minimum, self.bins)
maximum = float(max(self.bins))
self.bins = map(lambda b: b / maximum, self.bins)
def intersect(self, other):
h1 = self.bins
h2 = other.bins
......
......@@ -6,24 +6,20 @@ class LocalBinaryPatternizer:
def __init__(self, image, cell_size=16):
self.cell_size = cell_size
self.image = image
self.setup_histograms()
def setup_histograms(self):
cells_in_width = int(ceil(self.image.width / float(self.cell_size)))
cells_in_height = int(ceil(self.image.height / float(self.cell_size)))
self.features = []
self.histograms = []
for i in xrange(cells_in_height):
self.features.append([])
for j in xrange(cells_in_width):
self.features[i].append(Histogram(256,0,256))
self.histograms.append([])
def create_features_vector(self):
''' Walk around the pixels in clokwise order, shifting 1 bit less
at each neighbour starting at 7 in the top-left corner. This gives a
8-bit feature number of a pixel'''
for y, x, value in self.image:
for j in xrange(cells_in_width):
self.histograms[i].append(Histogram(256, 0, 256))
pattern = (self.is_pixel_darker(y - 1, x - 1, value) << 7) \
def local_binary_pattern(self, y, x, value):
return (self.is_pixel_darker(y - 1, x - 1, value) << 7) \
| (self.is_pixel_darker(y - 1, x , value) << 6) \
| (self.is_pixel_darker(y - 1, x + 1, value) << 5) \
| (self.is_pixel_darker(y , x + 1, value) << 4) \
......@@ -32,8 +28,15 @@ class LocalBinaryPatternizer:
| (self.is_pixel_darker(y + 1, x - 1, value) << 1) \
| (self.is_pixel_darker(y , x - 1, value) << 0)
def create_features_vector(self):
'''Walk around the pixels in clokwise order, shifting 1 bit less at
each neighbour starting at 7 in the top-left corner. This gives a 8-bit
feature number of a pixel'''
self.setup_histograms()
for y, x, value in self.image:
cy, cx = self.get_cell_index(y, x)
self.features[cy][cx].add(pattern)
self.histograms[cy][cx].add(self.local_binary_pattern(y, x, value))
return self.get_features_as_array()
......@@ -44,4 +47,27 @@ class LocalBinaryPatternizer:
return (y / self.cell_size, x / self.cell_size)
def get_features_as_array(self):
return [h.bins for h in [h for sub in self.features for h in sub]][0]
f = []
# Concatenate all histogram bins
for row in self.histograms:
for hist in row:
f.extend(hist.bins)
return f
#return [h.bins for h in [h for sub in self.histograms for h in sub]][0]
def get_single_histogram(self):
"""Create a single histogram of the local binary patterns in the
image."""
h = Histogram(256, 0, 256)
for y, x, value in self.image:
h.add(self.local_binary_pattern(y, x, value))
h.normalize()
return h
def single_cell_features_vector(self):
return self.get_single_histogram().bins
......@@ -5,7 +5,8 @@ from GaussianFilter import GaussianFilter
class NormalizedCharacterImage(GrayscaleImage):
def __init__(self, image=None, data=None, size=(60, 40), blur=1.1, crop_threshold=0.9):
def __init__(self, image=None, data=None, size=(60, 40), blur=1.1, \
crop_threshold=0.9):
if image != None:
GrayscaleImage.__init__(self, data=deepcopy(image.data))
elif data != None:
......@@ -13,18 +14,17 @@ class NormalizedCharacterImage(GrayscaleImage):
self.blur = blur
self.crop_threshold = crop_threshold
self.size = size
self.gausse_filter()
self.gaussian_filter()
self.increase_contrast()
self.crop_to_letter()
self.resize()
#self.crop_to_letter()
#self.resize()
def increase_contrast(self):
self.data -= self.data.min()
self.data /= self.data.max()
self.data = self.data.astype(float) / self.data.max()
def gausse_filter(self):
filter = GaussianFilter(1.1)
filter.filter(self)
def gaussian_filter(self):
GaussianFilter(self.blur).filter(self)
def crop_to_letter(self):
cropper = LetterCropper(0.9)
......
C = [2 ** p for p in xrange(-5, 16, 2)]:
Y = [2 ** p for p in xrange(-15, 4, 2)]
best_result = 0
#!/usr/bin/python
from cPickle import load
from Classifier import Classifier
C = [float(2 ** p) for p in xrange(-5, 16, 2)]
Y = [float(2 ** p) for p in xrange(-15, 4, 2)]
best_classifier = None
learning_set = load(file('learning_set', 'r'))
test_set = load(file('test_set', 'r'))
print 'Loading learning set...'
learning_set = load(file('learning_set.dat', 'r'))
print 'Learning set:', [c.value for c in learning_set]
print 'Loading test set...'
test_set = load(file('test_set.dat', 'r'))
print 'Test set:', [c.value for c in test_set]
# Perform a grid-search on different combinations of soft margin and gamma
results = []
best = (0,)
i = 0
for c in C:
for y in Y:
classifier = Classifier(c=c, gamma=y)
classifier.train(learning_set)
result = classifier.test(test_set)
if result > best_result:
best_classifier = classifier
if result > best[0]:
best = (result, c, y, classifier)
results.append(result)
i += 1
print '%d of %d, c = %f, gamma = %f, result = %d%%' \
% (i, len(C) * len(Y), c, y, int(round(result * 100)))
i = 0
print '\n c\y',
for y in Y:
print '| %f' % y,
print
for c in C:
print ' %7s' % c,
for y in Y:
print '| %8d' % int(round(results[i] * 100)),
i += 1
print
print 'c = %f, gamma = %f, result = %d%%' % (c, y, int(result * 100))
print '\nBest result: %.3f%% for C = %f and gamma = %f' % best[:3]
best_classifier.save('best_classifier')
best[3].save('classifier.dat')
#!/usr/bin/python
from os import listdir
from cPickle import dump
from pylab import imshow, show
from GrayscaleImage import GrayscaleImage
from NormalizedCharacterImage import NormalizedCharacterImage
from Character import Character
c = []
for char in sorted(listdir('../images/LearningSet')):
for image in sorted(listdir('../images/LearningSet/' + char)):
f = '../images/LearningSet/' + char + '/' + image
image = GrayscaleImage(f)
norm = NormalizedCharacterImage(image, blur=1, size=(48, 36))
#imshow(norm.data, cmap='gray')
#show()
character = Character(char, [], norm)
character.get_single_cell_feature_vector()
c.append(character)
print char
dump(c, open('characters.dat', 'w+'))
......@@ -3,7 +3,7 @@ from pylab import subplot, show, imshow, axis
from cPickle import load
x, y = 25, 25
chars = load(file('chars', 'r'))[:(x * y)]
chars = load(file('characters.dat', 'r'))[:(x * y)]
for i in range(x):
for j in range(y):
......
#!/usr/bin/python
from pylab import subplot, show, imshow, axis
from cPickle import load
chars = filter(lambda c: c.value == 'A', load(file('chars', 'r')))
for i in range(10):
for j in range(3):
index = j * 10 + i
subplot(10, 3, index + 1)
axis('off')
imshow(chars[index].image.data, cmap='gray')
show()
......@@ -3,57 +3,56 @@ from xml_helper_functions import xml_to_LicensePlate
from Classifier import Classifier
from cPickle import dump, load
chars = []
for i in range(9):
for j in range(100):
try:
filename = '%04d/00991_%04d%02d' % (i, i, j)
print 'loading file "%s"' % filename
# is nog steeds een licensePlate object, maar die is nu heel anders :P
plate = xml_to_LicensePlate(filename)
if hasattr(plate, 'characters'):
chars.extend(plate.characters)
except:
print 'epic fail'
chars = load(file('characters.dat', 'r'))
learning_set = []
test_set = []
print 'loaded %d chars' % len(chars)
#s = {}
#
#for char in chars:
# if char.value not in s:
# s[char.value] = [char]
# else:
# s[char.value].append(char)
#
#for value, chars in s.iteritems():
# learning_set += chars[::2]
# test_set += chars[1::2]
dump(chars, file('chars', 'w+'))
#----------------------------------------------------------------
chars = load(file('chars', 'r'))[:500]
learned = []
learning_set = []
test_set = []
for char in chars:
if learned.count(char.value) > 12:
if learned.count(char.value) == 70:
test_set.append(char)
else:
learning_set.append(char)
learned.append(char.value)
#print 'Learning set:', [c.value for c in learning_set]
#print 'Test set:', [c.value for c in test_set]
dump(learning_set, file('learning_set', 'w+'))
dump(test_set, file('test_set', 'w+'))
print 'Learning set:', [c.value for c in learning_set]
print 'Test set:', [c.value for c in test_set]
print 'Saving learning set...'
dump(learning_set, file('learning_set.dat', 'w+'))
print 'Saving test set...'
dump(test_set, file('test_set.dat', 'w+'))
#----------------------------------------------------------------
learning_set = load(file('learning_set', 'r'))
print 'Loading learning set'
learning_set = load(file('learning_set.dat', 'r'))
# Train the classifier with the learning set
classifier = Classifier(c=30, gamma=1)
classifier = Classifier(c=512, gamma=.125, cell_size=12)
classifier.train(learning_set)
classifier.save('classifier')
classifier.save('classifier.dat')
print 'Saved classifier'
#----------------------------------------------------------------
classifier = Classifier(filename='classifier')
test_set = load(file('test_set', 'r'))
print 'Loading classifier'
classifier = Classifier(filename='classifier.dat')
print 'Loading test set'
test_set = load(file('test_set.dat', 'r'))
l = len(test_set)
matches = 0
for i, char in enumerate(test_set):
prediction = classifier.classify(char)
prediction = classifier.classify(char, char.value)
if char.value == prediction:
print ':-----> Successfully recognized "%s"' % char.value,
......
#!/usr/bin/python
from GrayscaleImage import GrayscaleImage
from NormalizedCharacterImage import NormalizedCharacterImage
......
......@@ -5,32 +5,39 @@ from GrayscaleImage import GrayscaleImage
from cPickle import load
from numpy import zeros, resize
chars = load(file('chars', 'r'))[::2]
chars = load(file('characters.dat', 'r'))[::2]
left = None
right = None
for c in chars:
if c.value == '8':
if left == None:
left = c.image
elif right == None:
right = c.image
s = {}
for char in chars:
if char.value not in s:
s[char.value] = [char]
else:
break
s[char.value].append(char)
left = s['F'][2].image
right = s['A'][0].image
size = 16
size = 12
d = (left.size[0] * 4, left.size[1] * 4)
#GrayscaleImage.resize(left, d)
#GrayscaleImage.resize(right, d)
p1 = LocalBinaryPatternizer(left, size)
h1 = p1.get_single_histogram()
p1.create_features_vector()
p1 = p1.features
p2 = LocalBinaryPatternizer(right, size)
h2 = p2.get_single_histogram()
p2.create_features_vector()
p2 = p2.features
total_intersect = h1.intersect(h2)
s = (len(p1), len(p1[0]))
match = zeros(left.shape)
m = 0
......@@ -52,6 +59,7 @@ for y in range(s[0]):
m += intersect
print 'Match: %d%%' % int(m / (s[0] * s[1]) * 100)
print 'Single histogram instersection: %d%%' % int(total_intersect * 100)
subplot(311)
imshow(left.data, cmap='gray')
......
#!/usr/bin/python
from GaussianFilter import GaussianFilter
from GrayscaleImage import GrayscaleImage
......
#!/usr/bin/python
from Histogram import Histogram
his = Histogram(10, 10, 110)
......
#!/usr/bin/python
from GrayscaleImage import GrayscaleImage
from LocalBinaryPatternizer import LocalBinaryPatternizer
......
#!/usr/bin/python
from LetterCropper import LetterCropper
from GrayscaleImage import GrayscaleImage
......
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