mineur

[canny.git] / intro.tex

diff --git a/intro.tex b/intro.tex
index f8974ceecc9305c17292b9b0b68d9985cc81eba0..dd2457095000f0db30d6ddd869719378415cfe6b 100644 (file)
--- a/intro.tex
+++ b/intro.tex
@@ -16,13 +16,27 @@ cannot be applied there to discover stego-images in LSBM.
 The most accurate detectors for this matching are universal steganalysers such as~\cite{LHS08,DBLP:conf/ih/2005,FK12}
 which classify images thanks to extracted features from neighboring elements of noise residual.  
 
 The most accurate detectors for this matching are universal steganalysers such as~\cite{LHS08,DBLP:conf/ih/2005,FK12}
 which classify images thanks to extracted features from neighboring elements of noise residual.  
 

+

 LSB matching revisited (LSBMR)~\cite{Mielikainen06} have been recently introduced. 
 LSB matching revisited (LSBMR)~\cite{Mielikainen06} have been recently introduced. 

-This scheme deals with pairs of pixels instead of individual ones.
-It thus allows to decrease the number of modified bits per cover pixel 
-for the same payload compared to LSB replacement and LSBM and 
-and avoids the LSB replacement style asymmetry. Unfortunately, 
-detectors referenced above are able to distinguish between 
-stego content images and  cover images.  
+For a given pair of pixels, in which the LSB
+of the first pixel carries one bit of secret message, and the relationship
+(odd–even combination) of the two pixel values carries
+another bit of secret message. 
+
+
+
+In such a way, the modification
+rate of pixels can decrease from 0.5 to 0.375 bits/pixel
+(bpp) in the case of a maximum embedding rate, meaning fewer
+changes to the cover image at the same payload compared to
+LSB replacement and LSBM. It is also shown that such a new
+scheme can avoid the LSB replacement style asymmetry, and
+thus it should make the detection slightly more difficult than the
+LSBM approach based on our experiments
+
+
+
+

 
 Instead of (efficiently) modifying LSBs, there is also a need to select pixels whose value 
 modification minimizes a distortion function.
 
 Instead of (efficiently) modifying LSBs, there is also a need to select pixels whose value 
 modification minimizes a distortion function.


@@ -69,7 +83,7 @@ Section~\ref{sec:experiments} shows experiments on image quality, steganalytic e
 and compare them to state of the art steganographic schemes.
 Finally, concluding notes and future works are given in section~\ref{sec:concl}
 
 and compare them to state of the art steganographic schemes.
 Finally, concluding notes and future works are given in section~\ref{sec:concl}
 

-theory : ?
+