X-Git-Url: https://bilbo.iut-bm.univ-fcomte.fr/and/gitweb/canny.git/blobdiff_plain/4b63033789d12bbc41ec23cb66990c458be402b0..457be557d1bb33d5d169605464822243e0ed6232:/ourapproach.tex diff --git a/ourapproach.tex b/ourapproach.tex index e87c148..1b2ee1a 100644 --- a/ourapproach.tex +++ b/ourapproach.tex @@ -8,7 +8,8 @@ The message extraction is then presented (Sect.~\ref{sub:extract}) and a runnin The flowcharts given in Fig.~\ref{fig:sch} summarize our steganography scheme denoted by -STABYLO, which stands for STeganography with cAnny, Bbs, binarY embedding at LOw cost. +STABYLO, which stands for STeganography with +Adaptive, Bbs, binarY embedding at LOw cost. What follows are successively some details of the inner steps and the flows both inside the embedding stage (Fig.~\ref{fig:sch:emb}) and inside the extraction one (Fig.~\ref{fig:sch:ext}). @@ -372,35 +373,3 @@ This function allows to emphasize differences between contents. -\section{Complexity Analysis}\label{sub:complexity} -This section aims at justifying the leightweight attribute of our approach. -To be more precise, we compare the complexity of our schemes to the -state of the art steganography, namely HUGO~\cite{DBLP:conf/ih/PevnyFB10}. - - -In what folllows, we consider an $n \times n$ square image. -First of all, HUGO starts with computing the second order SPAM Features. -This steps is in $O(n^2 + 2.343^2)$ due to the calculation -of the difference arrays and next of the 686 features (of size 343). -Next for each pixel, the distortion measure is calculated by +1/-1 modifying -its value and computing again the SPAM -features. Pixels are thus selected according to their ability to provide -an image whose SPAM features are close to the original one. -The algorithm is thus computing a distance between each Feature, -which is at least in $O(343)$ and an overall distance between these -metrics which is in $O(686)$. Computing the distance is thus in -$O(2\time 343^2)$ and this mdification is thus in $O(2\time 343^2 \time n^2)$. -Ranking these results may be achieved with a insertion sort which is in $2.n^2 \ln(n)$. -The overall complexity of the pixel selection is thus -$O(n^2 +2.343^2 + 2\time 343^2 \time n^2 + 2.n^2 \ln(n))$, \textit{i.e} -$O(2.n^2(343^2 + \ln(n)))$. - -Our edge selection is based on a Canny Filter, -whose complexity is in $O(2n^2.\ln(n))$ thanks to the convolution step -which can be implemented with FFT. -The complexity of Hugo is at least $343^2/\ln{n}$ times higher than our scheme. - - - - -