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This is an archived project. Repository and other project resources are read-only.
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Taddeüs Kroes
licenseplates
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2772c2e1
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2772c2e1
authored
13 years ago
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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...
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@@ -153,35 +153,37 @@ rectangle.
\subsection*
{
Noise reduction
}
The image contains a lot of noise, both from camera errors due to dark noise
etc.,
as from dirt on the license plate. In this case, noise therefor means
any unwanted
difference in color from the surrounding pixels.
The image contains a lot of noise, both from camera errors due to dark noise
etc.,
as from dirt on the license plate. In this case, noise therefor
e
means
any unwanted
difference in color from the surrounding pixels.
\paragraph*
{
Camera noise and small amounts of dirt
}
The dirt on the licenseplate can be of different sizes. We can reduce the
smaller
amounts of dirt in the same way as we reduce normal noise, by applying
a gaussian
blur to the image. This is the next step in our program.
\\
The dirt on the licenseplate can be of different sizes. We can reduce the
smaller
amounts of dirt in the same way as we reduce normal noise, by applying
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
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
factor in this application.
most likely more optimized then our own implementation, and speed is an
important
factor in this application.
\paragraph*
{
Larger amounts of dirt
}
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
the difference between two pixels, to take care of these problems.
\\
Because there will probably always be a difference between the characters and 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.
We rely on one of the characteristics of the Local Binary Pattern, only looking
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 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
licenseplate is also available in de XML file, so this is parsed from that as well.
plate, by using a perspective transformation. The location of the characters on
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
}
...
...
@@ -194,15 +196,16 @@ licenseplate is also available in de XML file, so this is parsed from that as we
\section
{
Finding parameters
}
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
we have a number of parameters for which no standard choice is
available. These
parameters are:
\\
license plates. This means we need to find the parameters. Throughout the
program
we have a number of parameters for which no standard choice is
available. These
parameters are:
\\
\\
\begin{tabular}
{
l|l
}
Parameter
&
Description
\\
\hline
$
\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}
...
...
@@ -210,4 +213,4 @@ parameters are:\\
\end{document}
\ No newline at end of file
\end{document}
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