From: Jean-François Couchot Date: Thu, 9 Jan 2014 15:37:23 +0000 (+0100) Subject: y X-Git-Url: https://bilbo.iut-bm.univ-fcomte.fr/and/gitweb/canny.git/commitdiff_plain/30a1c774eb33c1344a68625e8958dbbd8b996280 y --- diff --git a/ourapproach.tex b/ourapproach.tex index 1410d5b..2378139 100644 --- a/ourapproach.tex +++ b/ourapproach.tex @@ -272,8 +272,8 @@ $\qquad$ In the ghoul-haunted woodland of Weir. The edge detection returns 18,641 and 18,455 pixels when $b$ is respectively 7 and 6. These edges are represented in Figure~\ref{fig:edge}. When $b$ is 7, it remains one bit per pixel to build the cover vector. -in this configuration, this leads to a cover vector of size 18,641 and -36,910 if $b$ is 6. +in this configuration, this leads to a cover vector of size 18,641 if b is 7 +and 36,910 if $b$ is 6. \begin{figure}[t] \begin{center} @@ -304,10 +304,16 @@ in this configuration, this leads to a cover vector of size 18,641 and The STC algorithm is optimized when the rate between message length and cover vector length is less than 1/2. -So, only 9,320 bits (resp. 18,455 bits) are available for embedding -in the former configuration where $b$ is 7 (resp. where $b$ is 6). -In the first cases, about the third part of the poem is hidden into the cover -whereas the latter allows to embed more than the half part of it. +So, only 9,320 bits are available for embedding +in the configuration where $b$ is 7. + +When $b$ is 6, we could have considered 18,455 bits for the message. +However, first experiments have shown that modifying this number of bits is too +easily detectable. +So, we choose to modify the same amount of bits (9,320) and keep STC optimizing +which bits to change among the 36,910 bits. + +In the two cases, about the third part of the poem is hidden into the cover. Results with \emph{adaptive+STC} strategy are presented in Fig.~\ref{fig:lenastego}.