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Taddeüs Kroes
licenseplates
Commits
2772c2e1
Commit
2772c2e1
authored
Dec 13, 2011
by
Jayke Meijer
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Made report comply to 80 chars limit.
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docs/verslag.tex
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2772c2e1
...
@@ -153,35 +153,37 @@ rectangle.
...
@@ -153,35 +153,37 @@ rectangle.
\subsection*
{
Noise reduction
}
\subsection*
{
Noise reduction
}
The image contains a lot of noise, both from camera errors due to dark noise
etc.,
The image contains a lot of noise, both from camera errors due to dark noise
as from dirt on the license plate. In this case, noise therefor means any unwanted
etc., as from dirt on the license plate. In this case, noise therefore means
difference in color from the surrounding pixels.
any unwanted
difference in color from the surrounding pixels.
\paragraph*
{
Camera noise and small amounts of dirt
}
\paragraph*
{
Camera noise and small amounts of dirt
}
The dirt on the licenseplate can be of different sizes. We can reduce the
smaller
The dirt on the licenseplate can be of different sizes. We can reduce the
amounts of dirt in the same way as we reduce normal noise, by applying a gaussian
smaller amounts of dirt in the same way as we reduce normal noise, by applying
blur to the image. This is the next step in our program.
\\
a gaussian
blur to the image. This is the next step in our program.
\\
\\
\\
The gaussian filter we use comes from the
\texttt
{
scipy.ndimage
}
module. We use
The gaussian filter we use comes from the
\texttt
{
scipy.ndimage
}
module. We use
this function instead of our own function, because the standard functions are
this function instead of our own function, because the standard functions are
most likely more optimized then our own implementation, and speed is an
important
most likely more optimized then our own implementation, and speed is an
factor in this application.
important
factor in this application.
\paragraph*
{
Larger amounts of dirt
}
\paragraph*
{
Larger amounts of dirt
}
Larger amounts of dirt are not going to be resolved by using a Gaussian filter.
Larger amounts of dirt are not going to be resolved by using a Gaussian filter.
We rely on one of the characteristics of the Local Binary Pattern, only looking at
We rely on one of the characteristics of the Local Binary Pattern, only looking
the difference between two pixels, to take care of these problems.
\\
at the difference between two pixels, to take care of these problems.
\\
Because there will probably always be a difference between the characters and the
Because there will probably always be a difference between the characters and
dirt, and the fact that the characters are very black, the shape of the characters
the dirt, and the fact that the characters are very black, the shape of the
will still be conserved in the LBP, even if there is dirt surrounding the character.
characters will still be conserved in the LBP, even if there is dirt
surrounding the character.
\subsection*
{
Character retrieval
}
\subsection*
{
Character retrieval
}
The retrieval of the character is done the same as the retrieval of the license
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
plate, by using a perspective transformation. The location of the characters on
licenseplate is also available in de XML file, so this is parsed from that as well.
the licenseplate is also available in de XML file, so this is parsed from that
as well.
\subsection*
{
Creating Local Binary Patterns and feature vector
}
\subsection*
{
Creating Local Binary Patterns and feature vector
}
...
@@ -194,15 +196,16 @@ licenseplate is also available in de XML file, so this is parsed from that as we
...
@@ -194,15 +196,16 @@ licenseplate is also available in de XML file, so this is parsed from that as we
\section
{
Finding parameters
}
\section
{
Finding parameters
}
Now that we have a functioning system, we need to tune it to work properly for
Now that we have a functioning system, we need to tune it to work properly for
license plates. This means we need to find the parameters. Throughout the
program
license plates. This means we need to find the parameters. Throughout the
we have a number of parameters for which no standard choice is available. These
program we have a number of parameters for which no standard choice is
parameters are:
\\
available. These
parameters are:
\\
\\
\\
\begin{tabular}
{
l|l
}
\begin{tabular}
{
l|l
}
Parameter
&
Description
\\
Parameter
&
Description
\\
\hline
\hline
$
\sigma
$
&
The size of the gaussian blur.
\\
$
\sigma
$
&
The size of the gaussian blur.
\\
\emph
{
cell size
}
&
The size of a cell for which a histogram of LBPs will be generated.
\emph
{
cell size
}
&
The size of a cell for which a histogram of LBPs will
be generated.
\end{tabular}
\end{tabular}
...
...
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