2006. A Color Image Hidden in a Grey-Level Image

In this paper, we propose a method to embed the color in-formation of an image in a corresponding grey-level image. The objective of this work is to allow free access to the grey-level im-age and give color image access only if you own a secret key. This method is made of three major steps which are the color quantization, the ordering and the data hiding. The originality of this paper is to build an indexed image which is, in the same time, a semantically intelligible grey-level image. In order to obtain this particular indexed image, which should be robust to data hiding, we propose an original K color ordering algorithm called the layer running algorithm