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Article: abstract and width control revisited

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\begin{abstract}
Penser \`a prendre du beurre sal\'e \`a la biocoop.
\end{abstract}
This paper introduces a new straight edge detector in gray-level images
based on blurred segments, digital objects able to imbed quality measurements
on the extracted features. This study completes previous works with a better
estimation of the blurred segment width and orientation, with the help of two
main improvements : adaptive directional scans and the control of the
assigned width to the recognition algorithm.
......@@ -34,9 +34,8 @@
\maketitle
\begin{abstract}
TOWRITE.
\keywords{Line detection \and discrete geometry \and TOCOMPLETE.}
\input{abstract}
\keywords{Line detection \and discrete geometry \and ONE MORE PLEASE.}
\end{abstract}
\end{frontmatter}
......
......@@ -52,15 +52,10 @@ The fine tracking step consists on building and extending a blurred segment
$\mathcal{B}_2$ based on points that correspond to local maxima of the
image gradient, ranked by magnitude order, and with gradient direction
close to a reference gradient direction at the segment first point.
This step uses an adaptive directional scanner based on the found
position $C$ direction $\vec{D}$ in order to extends the segment in the
At this refinement step, the control of the assigned width is applied
and an adaptive directional scanner based on the found position $C$ and
direction $\vec{D}$ is used in order to extends the segment in the
appropriate direction.
After $N$ points are added without any augmentation of the segment minimal
width, this width becomes the new assigned width so that the segment
can not thicken any more. This procedure allows to control the blurred
segment width based on the observation of its evolution in the vicinity
of the input stroke.
Setting $N=20$ shows a good behaviour on tested images.
The fine track output segment is finally filtered to remove artifacts
and outliers, and a solution blurred segment $\mathcal{B}_3$ is provided.
......
......@@ -52,15 +52,6 @@ the assigned width $\varepsilon$, then the new input point is rejected.}
\label{fig:bs}
\end{figure}
The control of the assigned width $\varepsilon$ is ensured on the
following way.
At the beginning, a large width $\varepsilon_0$ is assigned to the
recognition problem to allow the detection of large blurred segments.
Then, when no more aumentation of the minimal width is observed as the
segment grows ($\mu_{i+\lambda} = \mu_i$), the assigned width is set at
a near value to the observed minimal width in order to avoid the
incorporation of spurious outliers in further parts of the segment.
\subsection{Directional scan}
A directional scan $DS$ is an ordered partition restricted to the image
......@@ -214,8 +205,8 @@ An example of adaptive directional scan is given in \RefFig{fig:adaption}.
\begin{figure}[h]
\center
\begin{tabular}{c@{\hspace{0.2cm}}c}
\includegraphics[width=0.49\textwidth]{Fig_notions/adaptionBounds_zoom.png} &
\includegraphics[width=0.49\textwidth]{Fig_notions/adaptionLines_zoom.png}
\includegraphics[width=0.49\textwidth]{Fig_notions/adaptionBounds_zoom.png}
& \includegraphics[width=0.49\textwidth]{Fig_notions/adaptionLines_zoom.png}
\end{tabular}
\caption{Example of blurred segment detection
using an adaptive directional scan.
......@@ -225,3 +216,20 @@ An example of adaptive directional scan is given in \RefFig{fig:adaption}.
Adaption is quite sensible when crossing the tile joins.}
\label{fig:adaption}
\end{figure}
\subsection{Control of the assigned width}
The assigned width $\varepsilon$ to the blurred segment recognition algorithm
is initially set to a large value $\varepsilon_0$ in order to allow the
detection of large blurred segments.
Then, when no more augmentation of the minimal width is observed as the
blurred segment expends ($\mu_{i+\lambda} = \mu_i$), it is set to a much
stricter value able to circumscribe the possible interpretations of the
segment, that take into account the digitization margins:
\begin{equation}
\varepsilon = \mu_{i+\lambda} + 1/2
\end{equation}
This strategy aims at preventing the incorporation of spurious outliers in
further parts of the segment.
Setting the observation distance to a constant value $\lambda = 20$ seems
appropriate in most experimented situations.
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