Abstract
Techniques and applications for
information hiding have become
increasingly more sophisticated and
widespread. With high-resolution digital
images as carriers, detecting the presence
of hidden messages has also become
considerably more difficult. It is sometimes
possible, nevertheless, to detect (but not
necessarily decipher) the presence of
embedded messages. The basic approach
taken here works by finding predictable
higher-order statistics of "natural" images
within a multi-scale decomposition, and
then showing that embedded messages
alter these statistics.
The decomposition of images using
basis functions that are localized in spatial
position, orientation, and scale (such as
wavelets) has proven extremely useful in a
range of applications. One reason for this is
that such decompositions exhibit statistical
regularities that can be exploited.
The proposed algorithm consist of
three stages: Image feature extraction (IFE)
stage, training stage, and testing stage. In
IFE the image decomposes to four level
wavelet. Set of statistics (mean, skewness,
and kurtosis for each subband) is collected
from this decomposition. The
second set of statistics collected is
based on the errors in an optimal linear
predictor of coefficient magnitude. In this
predictor, the subband coefficients are
correlated to their spatial, orientation and
scale neighbors.
The steganalysis technique was tested
on samples of images processed with most
commercial steganographic software
products.