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Open Inventor Release 2023.2.3
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Open Inventor Release 2023.2.3
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The Hit-or-miss and Skeleton category contains engines used to produce simplified representations of the objects in an image, while preserving their geometrical structure. More...
The Hit-or-miss and Skeleton category contains engines used to produce simplified representations of the objects in an image, while preserving their geometrical structure.
The representations may then be used to calculate length, direction, etc. or to detect special topological structures such as end or triple points (number of crossings).
For example:
![\[
\begin{array}{ccc}
2 & 0 & 1\\
2 & 1 & 0\\
2 & 2 & 2
\end{array}
~~~\mbox{will match with}~~~
\begin{array}{ccc}
1 & 0 & 1\\
1 & 1 & 0\\
0 & 0 & 0
\end{array}
~~~\mbox{and}~~~
\begin{array}{ccc}
1 & 0 & 1\\
1 & 1 & 0\\
1 & 1 & 0
\end{array}
~~~\mbox{but not}~~~
\begin{array}{ccc}
0 & 1 & 1\\
0 & 1 & 0\\
0 & 0 & 0
\end{array}
\]](form_584_dark.png)
A LUT to convert a binary image from an 8 neighbors connexity to 4 neighbors connexity can be defined testing if a given pixel has a neighbour in the north east, north west, south west and south east directions.
![\[
~~~\mbox{north east}~~~
\begin{array}{ccc}
2 & 0 & 1\\
2 & 1 & 0\\
2 & 2 & 2
\end{array}
~~~\mbox{north west}~~~
\begin{array}{ccc}
1 & 0 & 2\\
0 & 1 & 2\\
2 & 2 & 2
\end{array}
~~~\mbox{south west}~~~
\begin{array}{ccc}
2 & 2 & 2\\
0 & 1 & 2\\
1 & 0 & 2
\end{array}
~~~\mbox{south east}~~~
\begin{array}{ccc}
2 & 2 & 2\\
2 & 1 & 0\\
2 & 0 & 1
\end{array}
\]](form_585_dark.png)
These kernels have to be added one by one to build the LUT, using the addKernel method. The first kernel has to be inserted with the mode NEW, that indicates the LUT has to be reset before to add this kernel inside. Other kernels have to be ineserted with the mode OR to indicate to look for this kernels or one of the previous.
For example : to change the connexity from 8 neighbors connexity to 4 , if the pixel matches the criteria the output value has to be forced to 0 and if it does not it has to be let unchanged. Therefore flagTrue = OUTPUT_ZERO and flagFalse = OUPUT_UNCHANGE.
![\[
\begin{tabular}{|c|c|c|}
\hline
\textbf{flagTrue} & \textbf{flagFalse} & \textbf{Operation}\\
\hline
ZERO & UNCHANGE & Thinning\\
\hline
ONE & UNCHANGE & Thickening\\
\hline
ONE & ZERO & Hit-or-misss\\
\hline
\end{tabular}
\]](form_586_dark.png)
![\[\begin{array}{ccc}
1 & 1 & 1\\
\times & \bullet & \times\\
0 & 0 & 0
\end{array}\]](form_587_dark.png)
where 
1.9.8 