Cryptography Reference
In-Depth Information
Fig. 5.10.
Six test palette images.
5.5 Conclusions
In this section, we discuss our proposed method and our experimental results.
Generally speaking, Tzeng et al.s method can be regarded as one special case
of clustering where the number of clusters is equal to the number of colors
on the palette. In this case, the total capacity includes only the capacity
D
om
, while the capacity D
cb
is zero. In other words, D
om
is the maximum
embedding capacity of Tzeng et al. method. With the help of the clustering
technique, our proposed method gains a larger embedding capacity, and it also
maintains quite good image quality by taking in the concept of embeddability.
As a result, when the number of clusters decreases, the embedding capacity
increases, and the PSNR value drops progressively.
Since the result of the clustering depends on the threshold value T
γ
,the
number of merged clusters is small, and the maximum cluster size is two when
the threshold value T
γ
is small. Here, the embedding capacity D
cb
is equal to
the number of embeddable pixels with
= 2. For this reason, only
one secret bit is embedded into a pixel. When the maximum cluster size of all
examples is larger than two, the embedding capacity will increase. More than
f (c
X(i,j)
)
