Adaptive Data Hiding Scheme for Palette Images - Intelligent Multimedia Data Hiding - page 98

5

Adaptive Data Hiding Scheme for Palette
Images

Chin-Chen Chang 1,2 , Yu-Zheng Wang 2 , and Yu-Chen Hu 3

1

Feng Chia University, Taichung, Taiwan, 40724, R.O.C.,
[e-mail] ,
WWW home page: http://www.cs.ccu.edu.tw/ ∼ ccc

2

Institute of Information Science, Academia Sinica, Taipei, 115, Taiwan, R.O.C.,
[e-mail]

3

Providence University, Taichung, Taiwan, R.O.C.

Summary. In this chapter, we propose a new data hiding scheme for palette image
applications that offer a high embedding capacity and good image quality. The
clustering technique is adopted to obtain the goal of high embedding capacity and
two embedding mechanisms. The first is the Cluster Ordering-and-Mapping Tech-
nique and the second is the combination technique. These are used to do embedding
according to the size of the cluster. The former scheme embeds one bit in the image
data with a cluster size of one, and the latter scheme makes more bits to be em-
bedded in the image data. A larger cluster size is made possible by combining the
elements of the cluster. According to our experimental results, the proposed method
contains a perfect balance between embedding capacity and image quality.

5.1 Introduction

In recent years, data hiding techniques [1, 2] have formed a widely investigated
field of research. The techniques are used to hide secret data, such as texts,
audio, and digital images into cover medium. The traditional encryption tech-
niques that encrypt the secret data by using a key leave clear marks on the
encrypted data for attackers to trace down. Consequently there is an urgent
need for better data hiding techniques. Data hiding techniques can camou-
flage the secret data so that attackers cannot easily detect the existence of
the secret data. Image hiding techniques shown in Fig. 5.1 basically work by
embedding secret information into a given image called the cover image or the
host image. This done by seamlessly modifying the bits without creating no-
ticeable artifacts [3, 4]. After embedding the secret data into the cover image,
the resultant image is called the Stego-Image. As the Stego-Image conceals
the existence of the secret data, only the receiver knows the data can then
be correctly extracted. This technique can be used in many applications, such
as Steganography, Secret Communication, Data Authentication, Annotation