A data hiding method for few-color images

The few-color images are often synthetic graphics without complicated color and texture variation, which makes the embedding of invisible digital watermark difficult. This paper proposes a data hiding method that can hide a moderate amount of data in a few-color image, such as cartoon images, binary images, without introducing noticeable artifacts. To achieve least visual quality reduction, the prioritized pattern matching scheme is employed to embed the invisible data in the pixels those are close to the boundaries. The block permutation is also exploited before embedding. No additional color is introduced and the palette keeps unchanged after embedding. Extracting of the hidden data does not require the knowledge of the original image. The experimental results show that the approach achieves a quite great performance in visibility transparency. It is applicable to invisible annotation, covert communication etc.