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Taddeüs Kroes
licenseplates
Commits
1d2ae333
Commit
1d2ae333
authored
Dec 21, 2011
by
Taddeus Kroes
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Merge branch 'master' of github.com:taddeus/licenseplates
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...
...
@@ -349,7 +349,7 @@ 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 trying them and checking the
results. It turned out that the best value was
$
\sigma
=
1
.
1
$
.
results. It turned out that the best value was
$
\sigma
=
1
.
4
$
.
\subsection
{
Parameter
\emph
{
cell size
}}
...
...
@@ -378,7 +378,13 @@ are not significant enough to allow for reliable classification.
The neighbourhood to use can only be determined through testing. We did a test
with each of these neighbourhoods, and we found that the best results were
reached with the following neighbourhood, which we will call the
()-neighbourhood.
(12, 5)-neighbourhood, since it has 12 points in a area with a diameter of 5.
\begin{figure}
[H]
\center
\includegraphics
[scale=0.5]
{
12-5neighbourhood.png
}
\caption
{
(12,5)-neighbourhood
}
\end{figure}
\subsection
{
Parameters
$
\gamma
$
\&
$
c
$}
...
...
@@ -399,8 +405,41 @@ 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
=
?
$
.
The results of this grid-search are shown in the following table. The values
in the table are rounded percentages, for easy displaying.
\begin{tabular}
{
|r|r r r r r r r r r r|
}
\hline
c
$
\gamma
$
&
$
2
^{
-
15
}$
&
$
2
^{
-
13
}$
&
$
2
^{
-
11
}$
&
$
2
^{
-
9
}$
&
$
2
^{
-
7
}$
&
$
2
^{
-
5
}$
&
$
2
^{
-
3
}$
&
$
2
^{
-
1
}$
&
$
2
^{
1
}$
&
$
2
^{
3
}$
\\
\hline
$
2
^{
-
5
}$
&
61
&
61
&
61
&
61
&
62
&
63
&
67
&
74
&
59
&
24
\\
$
2
^{
-
3
}$
&
61
&
61
&
61
&
61
&
62
&
63
&
70
&
78
&
60
&
24
\\
$
2
^{
-
1
}$
&
61
&
61
&
61
&
61
&
62
&
70
&
83
&
88
&
78
&
27
\\
$
2
^{
1
}$
&
61
&
61
&
61
&
61
&
70
&
84
&
90
&
92
&
86
&
45
\\
$
2
^{
3
}$
&
61
&
61
&
61
&
70
&
84
&
90
&
93
&
93
&
86
&
45
\\
$
2
^{
5
}$
&
61
&
61
&
70
&
84
&
90
&
92
&
93
&
93
&
86
&
45
\\
$
2
^{
7
}$
&
61
&
70
&
84
&
90
&
92
&
93
&
93
&
93
&
86
&
45
\\
$
2
^{
9
}$
&
70
&
84
&
90
&
92
&
92
&
93
&
93
&
93
&
86
&
45
\\
$
2
^{
11
}$
&
84
&
90
&
92
&
92
&
92
&
92
&
93
&
93
&
86
&
45
\\
$
2
^{
13
}$
&
90
&
92
&
92
&
92
&
92
&
92
&
93
&
93
&
86
&
45
\\
$
2
^{
15
}$
&
92
&
92
&
92
&
92
&
92
&
92
&
93
&
93
&
86
&
45
\\
\hline
\end{tabular}
We found that the best values for these parameters are
$
c
=
32
$
and
$
\gamma
=
0
.
125
$
.
\section
{
Results
}
...
...
@@ -416,7 +455,17 @@ measure the time used to classify a license plate, not the training of the
dataset, since that can be done offline, and speed is not a primary necessity
there.
\\
\\
The speed of a classification turned out to be ???.
The speed of a classification turned out to be reasonably good. We time between
the moment a character has been 'cut out' of the image, so we have a exact
image of a character, to the moment where the SVM tells us what character it is.
This time is on average
$
65
$
ms. That means that this
technique (tested on an AMD Phenom II X4 955 Quad core CPU running at 3.2 GHz)
can identify 15 characters per second.
\\
\\
This is not spectacular considering the amount of calculating power this cpu
can offer, but it is still fairly reasonable. Of course, this program is
written in Python, and is therefore not nearly as optimized as would be
possible when written in a low-level language.
\subsection
{
Accuracy
}
...
...
@@ -427,16 +476,31 @@ accuracy score we possibly can.\\
\footnote
{
\url
{
http://en.wikipedia.org/wiki/Automatic
_
number
_
plate
_
recognition
}}
,
commercial license plate recognition software score about
$
90
\%
$
to
$
94
\%
$
,
under optimal conditions and with modern equipment. Our program scores an
average of ???.
under optimal conditions and with modern equipment.
\\
\\
Our program scores an average of
$
93
\%
$
. However, this is for a single
character. That means that a full license plate should theoretically
get a score of
$
0
.
93
^
6
=
0
.
647
$
, so
$
64
.
7
\%
$
. That is not particularly
good compared to the commercial ones. However, our focus was on getting
good scores per character, and
$
93
\%
$
seems to be a fairly good result.
\\
\\
Possibilities for improvement of this score would be more extensive
grid-searches, finding more exact values for
$
c
$
and
$
\gamma
$
, more tests
for finding
$
\sigma
$
and more experiments on the size and shape of the
neighbourhoods.
\section
{
Conclusion
}
In the end it turns out that using Local Binary Patterns is a promising
technique for License Plate Recognition. It seems to be relatively
unsensitive
technique for License Plate Recognition. It seems to be relatively
indifferent
for the amount of dirt on license plates and different fonts on these plates.
\\
\\
The performance speedwise is ???
The performance speed wise is fairly good, when using a fast machine. However,
this is written in Python, which means it is not as efficient as it could be
when using a low-level languages.
\\
We believe that with further experimentation and development, LBP's can
absolutely be used as a good license plate recognition method.
\section
{
Reflection
}
...
...
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