抵禦影像攻擊之數位浮水印全相關技術之研究

Abstract

無

For the surveillance, home security and medical applications a digital watermarking scheme is needed to provide full correlation which is trivial in the normal techniques when any attack is predicted to occur. The correlation of decoded data varies according to the variations of length of the embedding data for the type of attack predicted. We believe that proper selection of length for the embedding data for any watermarking system can assure full correlation. In this thesis, we propose a framework which adds a preprocessor and a splitter for any regular watermark scheme at the embedder and a combiner at the decoder. A length boundary database is constructed with the congregation of various lookup tables which contain the maximum length values for various types of attacks predicted. In the framework, the preprocessor obtains the maximum length for the type of attack predicted from the length boundary database and checks this length with that of the embedding data. If the embedding data length is more than the maximum length obtained, the splitter divides it into pieces of data each of length equal to that of the maximum length chosen. The embedding data is thus embedded with the acceptable length to obtain full correlation.