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Article : enhanced comments of experiments

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\begin{tabular}{|l||r@{~$\pm~$}r|r@{~$\pm$~}r|r@{~$\pm$~}r|r@{~$\pm$~}r|r@{~$\pm$~}r|}
\hline
Measure $M$ & \multicolumn{2}{c|}{$T$ (ms)} & \multicolumn{2}{c|}{$C$ (\%)}
Measure & \multicolumn{2}{c|}{$T$ (ms)} & \multicolumn{2}{c|}{$C$ (\%)}
& \multicolumn{2}{c|}{$N$}
& \multicolumn{2}{c|}{$L$ (pixels)} & \multicolumn{2}{c|}{$L/N$} \\
\hline
......
......@@ -4,8 +4,8 @@ Detector : & \multicolumn{3}{c|}{old} & \multicolumn{3}{c|}{new} \\
\hline
Detected blurred segments per image
& 17.06 & $\pm$ & 3.22 & 16.83 & $\pm$ & 3.11 \\
Detected long (> 40 pixels) blurred segments per image
& 11.24 & $\pm$ & 1.94 & 11.36 & $\pm$ & 1.97 \\
%Detected long (> 40 pixels) blurred segments per image
%& 11.24 & $\pm$ & 1.94 & 11.36 & $\pm$ & 1.97 \\
Undetected input segments per image
& 0.152 & $\pm$ & 0.43 & \textbf{0.003} & $\pm$ & \textbf{0.05} \\
Precision (\%) : $P = \#(D\cap S)/\#D$
......
......@@ -212,3 +212,15 @@ in urban imagery},
year = {2010},
pages = {1086--1091}
}
@book{DesolneuxAl08,
author = {Desolneux, Agn\`es and Moisan, Lionel and Morel, Jean-Michel},
year = {2008},
month = {January},
pages = {273},
title = {From {G}estalt Theory to Image Analysis: A Probabilistic Approach},
series= {Interdisciplinary Applied Mathematics},
volume = {34},
doi = {10.1007/978-0-387-74378-3}
}
......@@ -24,27 +24,26 @@
%The segment minimal size is set to 5 pixels, except where precised.
In the experimental stage, the proposed approach is validated through
comparisons with other recent line detectors.
However only one of them, LSD \cite{GioiAl10}, provides a thickness value
of output lines, based on the width of regions with same gradient direction.
Unfortunately, this information does not really match the line sharpness
or scattering quality, that is addressed in this work, and can not be
actually compared to the thickness value output by the new detector.
comparisons with other recent line detectors: LSD \cite{GioiAl10},
ED-Lines \cite{AkinlarTopal12} and CannyLines \cite{LuAl15}.
Only LSD provides a thickness value
based on the width of regions with same gradient direction.
This information does not match the line sharpness or scattering quality
addressed in this work, so that it can not be actually compared to the
thickness value output by the new detector.
Moreover, we did not find any data base with ground truth including
line thickness.
Therefore we proceed in two steps :
(i) evaluation of the benefits brought by the new concepts to measure
the lines orientation and thickness on synthetic images;
(ii) evaluation of more global performance of the unsupervised detector
compared to other approaches.
For all these experiments, the stroke sweeping step is set to 15 pixels.
(i) evaluation on synthetic images of the new concepts enhancements
on line orientation and thickness estimation;
(ii) evaluation of more global performance of the proposed approach
compared to other detectors.
For all these experiments in unsupervised mode, the stroke sweeping step
is set to 15 pixels.
At first, the benefits of introduced concepts are evaluated through a
comparison of the performance of both versions of the detector
(with and without the concepts).
The test is performed on a set of 1000 synthesized images
containing 10 randomly
placed input segments with random thickness between 2 and 5 pixels.
At first, the performance of both versions of the detector (with and without
the concepts) is tested on a set of 1000 synthesized images containing 10
randomly placed input segments with random thickness between 2 and 5 pixels.
%Such controlled images can be considered as ground truths.
The initial assigned thickness $\varepsilon_0$ was set to 7 pixels
to detect all the lines in unsupervised mode.
......@@ -105,31 +104,26 @@ $D$ the set of all the detected blurred segments.}
\label{tab:synth}
\end{table}
Next experiments aim at comparing the achieved performance of the new
detector with those of other line detectors : LSD \cite{GioiAl10},
ED-Lines \cite{AkinlarTopal12} and CannyLines \cite{LuAl15}.
The tests are run on the York Urban database \cite{DenisAl08} composed
Next experiments aim at comparing the new approach with recent line detectors.
Tests are run on the York Urban database \cite{DenisAl08} composed
of 102 images with their ground truth lines.
As this database was set in the scope of Manhattan-world environments,
As it was set in the scope of Manhattan-world environments,
only lines in the three main directions are provided.
Initial assigned thickness $\varepsilon_0$ is set to 3 pixels, and
final length threshold to 10 points to suit the stroke sweeping step
value.
Results on one image are displayed in \RefFig{fig:york}.
Compared measures $M$ are execution time $T$, covering ratio $C$,
For these experiments, initial assigned thickness $\varepsilon_0$ is set
to 3 pixels, and final length threshold to 10 points to suit the stroke
sweeping step value.
Output lines smaller than 10 pixels are discarded for all the detectors.
Compared measures are execution time $T$, covering ratio $C$,
detected lines amount $N$, cumulated length of detected lines $L$ and
mean length ratio $L/N$.
On each image of the database we measure the execution time of 100 repetitions
of a complete detection, gradient extraction included, for each line detector;
$T$ is the mean value computed on the whole image set.
Tests are run on Intel Core i5 processor.
Assuming that a pixel of a ground truth line is identified
if there is a detected line in its 8-neighborhood, then the measure $C$ is
On each image of the database and for each line detector, the execution time
of 100 repetitions of a complete detection, gradient extraction included, was
measured using Intel Core i5 processor; $T$ is the mean value found per image.
Then, assuming that a pixel of a ground truth line is identified
if there is a detected line in its 8-neighborhood, measure $C$ is
the mean ratio of the length of ground truth line pixels identified on the
total amount of ground truth line pixels.
Detected lines smaller than 10 pixels are discarded for all the detectors.
Found measures are given in \RefTab{tab:comp}.
Results are given in \RefTab{tab:comp}.
\begin{figure}[h]
\center
......@@ -158,7 +152,7 @@ Found measures are given in \RefTab{tab:comp}.
\caption{Comparison of line detectors on one of the 102 ground truth
images of the York Urban database : a) input image, % P1020928
b) ground truth lines, c) LSD output, d) ED-Lines output,
e) CannyLines output, f) thick lines of the new detector.}
e) CannyLines output, f) thick lines of the new detector. }
\label{fig:york}
\end{figure}
......@@ -167,12 +161,18 @@ Found measures are given in \RefTab{tab:comp}.
\input{Expe_auto/compTable}
\caption{Measured performance of recent line detectors and of our detector
on the York Urban Database \cite{DenisAl08}.}
on the York Urban Database \cite{DenisAl08}. }
\label{tab:comp}
\end{table}
On these images, CannyLines provides longer lines and ED-Lines is much faster.
Globally, the performance of the new detector is pretty similar and
competitive to the other ones, and
furthermore, our detector provides an indication
Results displayed on the example of \RefFig{fig:york} indicate that
the new detector produces many small segments, that could be considered as
visually non-meaningful. The other detectors eliminates them by a
validation test based on Helmholtz principle \cite{DesolneuxAl08}.
Such test is not yet integrated into the new detector.
But even so, the mean length of output lines is greater.
Except for execution time for ED-Lines performs best,
global performance of the new detector is pretty similar and
competitive to the other ones.
Furthermore, it provides additional information
on the detected line quality through the estimated thickness.
......@@ -263,7 +263,7 @@ An option, called {\it multi-detection} (Algorithm 1), allows the
detection of all the segments crossed by the input stroke $AB$.
In order to avoid multiple detections of the same edge, an occupancy mask,
initially empty, collects the dilated points of all the blurred segments,
so that these points can not be added to another segment.
so that these points can not be used any more.
\input{Fig_method/algoMulti}
First the positions $M_j$ of the prominent local maxima of the gradient
......
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