High Capacity Image Data Hiding Scheme for Grouping Palette Index

Applying the image palette to hide information, we usually embed them into the palette itself or into the index table of the image. Although the hiding schemes in palette could be a simpler way, the palette becomes more complicated and reveals that the information is embedded. In this paper, we will use the index table of image to conceal information. The proposed method selects a threshold value and picks the color with highest probability of appearance as a center to group the color pixels. The system evaluates Euclidean distances from the center to each of the pixels and collects the color pixels in the same group if the distance is less than or equal to the threshold value. In the embedding procedure, the system applies orderly the value of each bit of a secret key to shift the coordinate of color pixel. The extraction procedure groups the pixels, shifts according to the key value and determines whether the group is valid. Then, the information can be extracted from each group till all the pixels are determined. From the experimental results, the method increases the embedding capacity of information and improves the image quality efficiently. Furthermore, our method enhances the security of the system because the secret key is applied to shift the coordinate.