From: Jean-François Couchot <couchot@couchot.iut-bm.univ-fcomte.fr>
Date: Fri, 21 Dec 2012 13:50:32 +0000 (+0100)
Subject: Merge branch 'master' of ssh://info.iut-bm.univ-fcomte.fr/canny
X-Git-Url: https://bilbo.iut-bm.univ-fcomte.fr/and/gitweb/canny.git/commitdiff_plain/274073a1e4ae1b4de1220e26626a582a08a890d6?hp=01e8c9301dc7bf227e7fbe18962c62bcb9cc848f

Merge branch 'master' of ssh://info.iut-bm.univ-fcomte.fr/canny
---

diff --git a/biblio.bib b/biblio.bib
index 5680580..22bcda2 100644
--- a/biblio.bib
+++ b/biblio.bib
@@ -255,18 +255,6 @@ author    = {Jessica J. Fridrich and
   year = 2001
 }
 
-@proceedings{DBLP:conf/ih/2001,
-  editor    = {Ira S. Moskowitz},
-  title     = {Information Hiding, 4th International Workshop, IHW 2001,
-               Pittsburgh, PA, USA, April 25-27, 2001, Proceedings},
-  booktitle = {Information Hiding},
-  publisher = {Springer},
-  series    = {Lecture Notes in Computer Science},
-  volume    = {2137},
-  year      = {2001},
-  isbn      = {3-540-42733-3},
-  bibsource = {DBLP, http://dblp.uni-trier.de}
-}
 
 @inproceedings{DBLP:conf/ih/KimDR06,
   added-at = {2007-09-20T00:00:00.000+0200},
@@ -287,7 +275,7 @@ author    = {Jessica J. Fridrich and
   series = {Lecture Notes in Computer Science},
   timestamp = {2007-09-20T00:00:00.000+0200},
   title = {Modified Matrix Encoding Technique for Minimal Distortion Steganography.},
-  url = {http://dblp.uni-trier.de/db/conf/ih/ih2006.html#KimDR06},
+  url = {http://dblp.uni-trier.de/db/conf/ih/ih206.html#KimDR06},
   volume = 4437,
   year = 2006
 }
diff --git a/experiments.tex b/experiments.tex
index 0b4d6d7..0011cd4 100644
--- a/experiments.tex
+++ b/experiments.tex
@@ -39,6 +39,7 @@ Compare to the Edge Adpative scheme detailed in~\cite{Luo:2010:EAI:1824719.18247
 \JFC{comparer aux autres approaches}
 
 
+
 \subsection{Steganalysis}
 
 
@@ -77,4 +78,3 @@ Ensemble Classifier &   &      &      \\
 \end{table}
 
 
-\JFC{Raphael, il faut donner des résultats ici}
\ No newline at end of file
diff --git a/ourapproach.tex b/ourapproach.tex
index 4539cf1..f832695 100644
--- a/ourapproach.tex
+++ b/ourapproach.tex
@@ -85,6 +85,27 @@ modifies canny parameters to get a sufficiently large set of edge bits: this
 one is practically enlarged untill its size is at least twice as many larger 
 than the size of embedded message.
 
+Edge Based Image Steganography schemes 
+already studied~\cite{Luo:2010:EAI:1824719.1824720,DBLP:journals/eswa/ChenCL10,DBLP:conf/ih/PevnyFB10} differ 
+how they select edge pixels, and  
+how they modify these ones.
+
+First of all, let us discuss about compexity of edge detetction methods.
+Let then $M$ and $N$ be the dimension of the original image. 
+According to~\cite{Hu:2007:HPE:1282866.1282944},
+even if the fuzzy logic based edge detection methods~\cite{Tyan1993} 
+have promising results, its complexity is in $C_3 \times O(M \times N)$
+whereas the complexity on the Canny method~\cite{Canny:1986:CAE:11274.11275} 
+is in $C_1 \times O(M \times N)$ where  $C_1 < C_3$.
+\JFC{Verifier ceci...}
+In experiments detailled in this article, the canny method has been retained 
+but the whole approach can be updated to consider 
+the fuzzy logic edge detector.   
+
+Next, following~\cite{Luo:2010:EAI:1824719.1824720}, our scheme automatically
+modifies canny parameters to get a sufficiently large set of edge bits: this 
+one is practically enlarged untill its size is at least twice as many larger 
+than the size of embedded message.
 
 
 \subsubsection{Security Considerations}
@@ -104,6 +125,21 @@ it would thus be not possible to retrieve the original one in a
 polynomial time.   
 
 
+\subsubsection{Security Considerations}
+Among methods of message encryption/decryption 
+(see~\cite{DBLP:journals/ejisec/FontaineG07} for a survey)
+we implement the Blum-Goldwasser cryptosystem~\cite{Blum:1985:EPP:19478.19501}
+which is based on the Blum Blum Shub~\cite{DBLP:conf/crypto/ShubBB82} Pseudo Random Number Generator (PRNG) 
+for security reasons.
+It has been indeed proven~\cite{DBLP:conf/crypto/ShubBB82} that this PRNG 
+has the cryptographically security property, \textit{i.e.}, 
+for any sequence $L$ of output bits $x_i$, $x_{i+1}$, \ldots, $x_{i+L-1}$,
+there is no algorithm, whose time complexity is polynomial  in $L$, and 
+which allows to find $x_{i-1}$ and $x_{i+L}$ with a probability greater
+than $1/2$.
+Thus, even if the encrypted message would be extracted, 
+it would thus be not possible to retrieve the original one in a 
+polynomial time.   
 
 
 
diff --git a/stc/exp/raphus/test_wpsnr.py b/stc/exp/raphus/test_wpsnr.py
new file mode 100644
index 0000000..f735467
--- /dev/null
+++ b/stc/exp/raphus/test_wpsnr.py
@@ -0,0 +1,42 @@
+import Image as im
+import numpy as np
+from Image import ImageStat as imst
+from numpy import linalg as LA
+
+from math import *
+
+
+
+def sig2(mat):
+    (h,l) = mat.shape
+    L= 1
+    avx = np.empty((h,l))
+    for i in xrange(h):
+        for j in xrange(l):
+            avx[i,j] = np.average([mat[ip,jp] 
+                                   for ip in xrange(max(0,i-L),min(h,i+L))
+                                   for jp in xrange(max(0,j-L),min(h,j+L))])
+            
+    s2 = np.empty((h,l))
+    for i in xrange(h):
+        for j in xrange(l):
+            s2[i,j] = np.average([(mat[ip,jp]- avx[ip,jp])**2
+                                  for ip in xrange(max(0,i-L),min(h,i+L))
+                                  for jp in xrange(max(0,j-L),min(h,j+L))])
+    return s2
+
+def nvf(mat):
+    D = 75
+    (h,l) = mat.shape
+    N = np.empty((h,l))
+    
+    s2 = sig2(mat)
+    sigmax = np.amax(s2)
+
+    for i in xrange(h):
+        for j in xrange(l):        
+            N[i,j] = float(1)/(1+sigmax(i,j)**2)
+    
+
+def wpsnr(mati,mato):
+    return 10 * log10( (float(np.amax(mati))/(LA.norm(nvf(mato-mati))))**2)