\begin{figure}[t]
\centering
- \subfigure[Airplane image, corrupted by salt and pepper noise of density 0.25]{\label{img:sap_example_ref} \includegraphics[width=5cm]{Chapters/chapter3/img/airplane_sap25.png}}\qquad
- \subfigure[Image denoised by a $3\times 3$ median filter]{\label{img:sap_example_med3} \includegraphics[width=5cm]{Chapters/chapter3/img/airplane_sap25_med3.png}}\\
- \subfigure[Image denoised by a $5\times 5$ median filter]{\label{img:sap_example_med5} \includegraphics[width=5cm]{Chapters/chapter3/img/airplane_sap25_med5.png}}\qquad
- \subfigure[Image denoised by 2 iterations of a $3\times 3$ median filter]{\label{img:sap_example_med3_it2} \includegraphics[width=5cm]{Chapters/chapter3/img/airplane_sap25_med3_it2.png}}\\
+ \subfigure[Airplane image, corrupted by salt and pepper noise of density 0.25]{ \includegraphics[width=5cm]{Chapters/chapter3/img/airplane_sap25.png}}\qquad
+ \subfigure[Image denoised by a $3\times 3$ median filter]{ \includegraphics[width=5cm]{Chapters/chapter3/img/airplane_sap25_med3.png}}\\
+ \subfigure[Image denoised by a $5\times 5$ median filter]{ \includegraphics[width=5cm]{Chapters/chapter3/img/airplane_sap25_med5.png}}\qquad
+ \subfigure[Image denoised by 2 iterations of a $3\times 3$ median filter]{ \includegraphics[width=5cm]{Chapters/chapter3/img/airplane_sap25_med3_it2.png}}\\
\caption{Example of median filtering, applied to salt and pepper noise reduction.}
\label{fig:sap_examples}
\end{figure}
It has to be noticed that this smoother, unlike the technique we proposed for fixed-size median filters, cannot be considered as a state-of-the-art technique as, for example, the one presented in \cite{4287006}. However, it may be considered as a good, easy to use and efficient alternative as confirmed by the results presented in Table \ref{tab:medianSeparable}. Pixel throughput values achieved by our kernel, though not constant with window size, remain very competitive if window size is kept under $120\times 120$ pixels, especially when outputting 2 pixels per thread (in \cite{4287006}, pixel throughput is around 7MP/s).
Figure \ref{fig:sap_examples2} shows an example of a $512\times 512$ pixel image, corrupted by a \textit{salt and pepper} noise, and the denoised versions, outputted respectively by a $3\times 3$, a $5\times 5$, and a $55\times 55 $ separable smoother.
\begin{figure}
- \subfigure[Airplane image, corrupted with by salt and pepper noise of density 0.25]{\label{img:sap_example_ref} \includegraphics[width=5cm]{Chapters/chapter3/img/airplane_sap25.png}}\qquad
- \subfigure[Image denoised by a $3\times 3$ separable smoother]{\label{img:sap_example_sep_med3} \includegraphics[width=5cm]{Chapters/chapter3/img/airplane_sap25_sep_med3.png}}\\
- \subfigure[Image denoised by a $5\times 5$ separable smoother]{\label{img:sap_example_sep_med5} \includegraphics[width=5cm]{Chapters/chapter3/img/airplane_sap25_sep_med5.png}}\qquad
- \subfigure[Image background estimation by a $55\times 55$ separable smoother]{\label{img:sap_example_sep_med3_it2} \includegraphics[width=5cm]{Chapters/chapter3/img/airplane_sap25_sep_med111.png}}\\
+ \subfigure[Airplane image, corrupted with by salt and pepper noise of density 0.25]{ \includegraphics[width=5cm]{Chapters/chapter3/img/airplane_sap25.png}}\qquad
+ \subfigure[Image denoised by a $3\times 3$ separable smoother]{ \includegraphics[width=5cm]{Chapters/chapter3/img/airplane_sap25_sep_med3.png}}\\
+ \subfigure[Image denoised by a $5\times 5$ separable smoother]{ \includegraphics[width=5cm]{Chapters/chapter3/img/airplane_sap25_sep_med5.png}}\qquad
+ \subfigure[Image background estimation by a $55\times 55$ separable smoother]{ \includegraphics[width=5cm]{Chapters/chapter3/img/airplane_sap25_sep_med111.png}}\\
\caption{Example of separable median filtering (smoother), applied to salt and pepper noise reduction.}
\label{fig:sap_examples2}
\end{figure}