Improving Prediction Error Expansion based data hiding method for securing confidential data

Development of information technology has supported the delivery of multimedia document such as images, audio or video that can be applied in many fields of activity. Nevertheless, this implementation requires security treatment for sensitive data. Reversible Data Hiding methods are an option to meet this requirement. One of them which can be used is Prediction Error Expansion. This method embeds secret data into expanded prediction error which is a difference between pixel for data embedding and pixel for prediction. To improve the quality of stego image, the Pixel-Value-Ordering concept is applied when embedding data. This approach is further developed by utilizing an expanded prediction error value of 0, so that it can increase the capacity of data embedding. This method, however, only uses smooth block and is not suitable for block pixels whose size is more than 2×2. In this paper, we propose a new embedding concept that can utilize another block type (e.g. rough type). Furthermore, we also propose a 2 bit embedding concept with prevention, to keep the stego image quality still good. The experimental result shows the average of stego image quality increases by 4.6 dB with capacity 5-10 times bigger than that of the previous method.